View Full Version : Battery Charging Station
For an Engineering Design and Development class, my partner and I have decided to make a new battery charging station for our senior project, since the one that we made last year ended up breaking on us. We were wondering if any of you guys had any ideas you'd like to share or suggestions of what to include in our project.
It would also be very helpful to fill out this survey. It will help us identify more constraints and help result in a better cart.
https://docs.google.com/forms/d/1o2HneEZrV_ahWW0qI26vAvsEHFKX9mJlFyzJadZP8Oo/viewform
-Thanks
For my design, I am aiming at simplicity of use, and functional. My battery cart shall be able to run on it's own without an external power source, to charge robot batteries. ::safety::
Here's My project Synopsis:
http://devstuff.no-ip.biz:890/?page_id=58
Curious - Are you planning on using chargers that can also desulfate?
That is a great idea :cool: . However, aren't chargers with the ability to desulfate fairly expensive, and often quite heavy?:rolleyes: Weight may not be too much of a problem is a motorized drive used (using motors like window motors!)::safety::
MichaelBick
21-11-2013, 22:59
(using motors like window motors!)::safety::
Window motors aren't very powerful whatsoever
We just got a charger/constant desulfator from BatteryMinder. http://batteryminders.com/details.php?prod=2012
We just got it in but it charges well. We will be running tests with an old battery and BatteryBeak to confirm how well it works.
They are geared down quite a bit, so four of these window motors are quite some power! I can imagine a team using window motors for their drivetrain!:D
They are geared down quite a bit, so four of these window motors are quite some power! I can imagine a team using window motors for their drivetrain!:D
To speak for Billfred and FRC1293: Never again! (If I'm wrong, fellas, let me know...)
Devyash, I think you need to do some study of the spec sheets. Yes, the window motors have some power--but if you look, they're weak, with a capital "weak". Compared to the CIM especially. Looking at the FRC official specs (http://www.usfirst.org/sites/default/files/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2013/2013MotorInformation.pdf), the Densos only put out 23W--at MAX power. The CIMs? 337W, or more than 10x the window motors. The only motor weaker than the Denso window motors is the other Denso motor (18W), or the VEX motors (4W).
You've been fooled by their non-backdriveability. The worm gears in their transmissions (which, IIRC, are ruled integral to the motor) keep them from going backwards when loaded. That said, having that sort of thing--with a proper clutch to allow the cart to move without power applied--does have its advantages (follow the link below).
Now, an anecdote to explain my earlier comment about "never again"... There WAS a team that used window motors in their drivetrain, about a decade ago.
http://www.chiefdelphi.com/media/photos/19905 for pictures and reason--original thread seems to have been deleted.
Jon Stratis
21-11-2013, 23:46
They are geared down quite a bit, so four of these window motors are quite some power! I can imagine a team using window motors for their drivetrain!:D
No, they really aren't. Each window motor has 23W of power - 4 of them would be 92W. In comparison, a single CIM motor has 337W of power. Correctly geared, a CIM motor is both faster (speed) and stronger (torque) than a window motor.
http://www.usfirst.org/sites/default/files/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2013/2013MotorInformation.pdf
They are geared down quite a bit, so four of these window motors are quite some power! I can imagine a team using window motors for their drivetrain!:D
You seem to be confusing power and torque.
Sorry for the confusion. I mean high torque, low speed! :)
Also, another up on those window motors is that they will automatically brake because they consist of a worm drive!
If you guys are wondering about my power ideas, currently, I am planning marine batteries. Has anyone used those WInston LIS batteries (http://www.winston-battery.com/index.php/products/battery/category/lsp%E7%B3%BB%E5%88%97)? They seem too good to be true. Hopefully you guys have google translate. That site is in Chinese!
BurkeHalderman
22-11-2013, 00:44
Also, another up on those window motors is that they will automatically brake because they consist of a worm drive!
No. Just no.
A worm gear will not break under a drivetrain application if used properly. In fact AndyMark offers a worm gear gearbox to be used for various applications such as lifting and drive. The advantage for using a worm gear is the anti-backdrive properties. Yes the KOP windows motors are breakable, but not all worm drives are made from cheaper plastic such as the KOP denso window motors. And if you break the worm gear a window motor then chances are some re-designing should be done.
AndyMark WormBox:
http://www.andymark.com/product-p/am-0917.htm
Team 1293 used window motors for their drive in 2003:
http://www.chiefdelphi.com/forums/showthread.php?t=33926
Basically why use window motors in a drivetrain application when much more suitable options are available.
Back to the OP's question, what I look for in a battery charging station is how many batteries it can hold, how many it can charge at once, maneuverability, and it's footprint. I'd recommend that your charging station should hold a minimum of six batteries, any less and you run a chance of not having fully charged batteries late in the competition (this is based off of my own experiences). As far as charging I'd get a 3-battery charger from AM:
http://www.andymark.com/Battery-Charger-3-Bank-6-Amp-p/am-2026.htm
We used one of for the last two seasons and they are great.
The charging station should be fairly maneuverable, and like everything in your pit should have a small footprint. The more room in your pit to work on the robot the better.
Here's an example of what I would consider the perfect cart:
http://www.chiefdelphi.com/forums/showthread.php?t=102222&highlight=pwnage+cart
However it all depends on your resources. I look forward to seeing the results.
MichaelBick
22-11-2013, 01:18
Sorry for the confusion. I mean high torque, low speed! :)
Just with 12 batteries you are looking at 156 lbs. Add in 35 for chargers and frame you are at 190 lbs. Just looking at the batteries you mention you need to add another 40 lbs. With window motors on a 4:1 so that you get reasonable current draw you are at .5fps. That is insanely slow. CIMs would likely be the much better fit here as they have a relatively low RPM, are high power, and are built like tanks.
Yeah...I guess that I overestimated window motors! Their gear ratio seems better than it actually is
MichaelBick
22-11-2013, 09:46
Yeah...I guess that I overestimated window motors! Their gear ratio seems better than it actually is
It's not about the gear ratio, it is about the power. Any motor can be geared down so that you have enough torque, however speed will obviously suffer. Therefor you need a motor with adequate power so that you have enough torque AND speed.
What do you think about BAG motors? They have a nice torque and their RPM is high! Gearing it down shall allow it to do weight lifting, shoudn't it?
Mark Sheridan
22-11-2013, 16:06
What do you think about BAG motors? They have a nice torque and their RPM is high! Gearing it down shall allow it to do weight lifting, shoudn't it?
What's wrong with pushing a battery cart? Seriously our teams costco runs for snack and drinks is way more then 200 lbs. Pushing that stuff is not hard. yeah a bag motor may work with the right gearing but is it worth it? I much rather investing that time to make sure the ergonomics of the rack nice.
Kinda steering this back to the original poster's question. We are tinkering with a battery rack this year that is ergonomic and organized. We want to have the charger display next to its corresponding battery and all the wiring tied to the frame. We will have a power strip inside so we will only have one plug to deal with. We may make it modular to the racks can be divided into smaller chunks. 3 rack with 4 batteries each may be more manageable.
I think its more better to go through a design matrix and hone the battery cart to practical design specs. I don't think self propulsion is high on that list. having good ergonomics, ease of battery removal, locking casters, durable frame and clean wiring are much more important features to consider. I think this is a good lesson for students to think about ergonomics, something I see often as an afterthought in manufacturing.
BurkeHalderman
22-11-2013, 17:05
What do you think about BAG motors? They have a nice torque and their RPM is high! Gearing it down shall allow it to do weight lifting, shoudn't it?
The BAG motors are designed more for a high speed, low torque application. When thinking about what kinds of motors to use you should be looking at their specifications. For example the BAG motor has a free speed of 14,000+ RPM's, a stall current draw of 41A, and a stall torque of only .4N•m. Compare this to the CIM Motor which has a free speed of 5,310 RPM's, a stall current draw of 133A and a stall torque of 2.42N•m. The CIM motor is a work horse motor much better suited for a drive application. Keep the BAG motors and RS-series motors in more suitable applications for their specs, such as an intake, flywheel, etc.
What's wrong with pushing a battery cart?
I agree, all this talk about motorized and/or remote controlled toolboxes, robot carts, and charging stations, why not just push it the old fashion way. Besides adding motors and controls and such only adds weight, time, and money. Which could be spent on better things like the robot.
I also am not a big fan of the idea of motorized drive. A castor can easily make it possible to push the load. However, I am guessing that I may reach 400 pounds or more! At that weight, an assisting system will help. I want it so the motor doesn't push, but just aids the person pushing the cart!
Mark Sheridan
22-11-2013, 18:49
I also am not a big fan of the idea of motorized drive. A castor can easily make it possible to push the load. However, I am guessing that I may reach 400 pounds or more! At that weight, an assisting system will help. I want it so the motor doesn't push, but just aids the person pushing the cart!
I think lifting 400 pounds of cart into a vehicle is a bigger issue than pushing the cart. I have gotten that much stuff into a truck with 4 people but it would be easier if it could be decided into smaller portions. Do you see that by dividing the cart into smaller pieces you can solve several issues? Or just use more people to solve the task
You've seen forklifts and pallet movers right? Most pallet movers are not motorized because pushing an heavy object on a flat surface only require you to overcome the friction and inertia of the object. However, were forklifts are used to move objects vertically or over inclines and thus are motorized. My work has motorized pallet movers but they are also forklifts. In the warehouse, there may be an object that has too much inertia to accelerate or decelerate but thats over a thousands pounds. I have moved 2,000 pound fixtures and it can be done by humans. We even skipped using the forklift because we a dozen people to help. However, a battery charging station can be decided into smaller pieces, I did not have this luxury when moving the 2,000 pound fixture.
I think a better exercise for motors would be CADing drives for robots. Last year, we had 3 separate CAD proposals. Even if you don't use them, its worth while to CAD and learn.
400 pounds is with all the batteries and items already inside. The marine battery is probably not going to be carried in the cart because the cart could tip over and the battery can leak!
MichaelBick
22-11-2013, 19:10
400 lbs sounds like a lot. Our is probably going to be a bit over 200 lbs. What are you putting in this cart that makes it so heavy? It sounds like it might be a better idea to separate things than just add on motors to help push it.
A castor can easily make it possible to push the load. However, I am guessing that I may reach 400 pounds or more! At that weight, an assisting system will help.
I routinely move a lot (capital "a lot") more than that with just another person on the other end of the cart to steer that end (and push). No assistance device needed.
If the cart didn't have wheels, you would have a problem. But 400 lb on wheels with 1-2 people handling it? You don't need assistance from a drive system.
Well, I was thinking of 6-12 batteries, chargers for them, state-of-art control board, Inverter and marine-cycle battery. Also, some storage space. The driver station should dock on, for charging and a place to keep. This cart has the ability to be a mobile power outlet capable of a couple KiloWatts!
BurkeHalderman
23-11-2013, 00:06
Well, I was thinking of 6-12 batteries, chargers for them, state-of-art control board, Inverter and marine-cycle battery. Also, some storage space. The driver station should dock on, for charging and a place to keep. This cart has the ability to be a mobile power outlet capable of a couple KiloWatts!
It appears your 400lb estimate is including all of the materials needed to make the cart motorized. If these weren't included the weight would be dramatically less. Lets assume this cart holds 12 batteries and 4 3-battery chargers. Each battery weighs 13.8lbs and each charger only weighs 7lbs for a total of approximately 195lbs. Now consider the bare frame of the cart weighs 20lbs (this is just based on our own charging station) for a grand total of 215lbs. Put this on wheels and you'll have no problem moving it around without motorizing it. And I don't see a need to turn it into a mobile power generator when there are multiple outlets available in the pits. Having a dock for your driver's station is a great idea though, will definitely consider integrating something like that.
Devyash please don't misinterpret my comments in a negative way, I merely want the OP to get the best information possible, after all that's why this thread is here.
Curious - Are you planning on using chargers that can also desulfate?
I dont think we are
That may be a great idea, because that will make sure that you pinch the power of those batteries completely.
Hey, I wonder if that would even be allowed. In a way, that is tampering with the battery and I think there are some safety problems with that!::ouch:: ::safety::
Invictus3593
26-11-2013, 09:24
That may be a great idea, because that will make sure that you pinch the power of those batteries completely.
Hey, I wonder if that would even be allowed. In a way, that is tampering with the battery and I think there are some safety problems with that!::ouch:: ::safety::
For safety's sake, I work at a battery store and, from experience, I can say it would not be wise to tamper with or open up in any way, the competition batteries or any battery like them. The lead acid inside won't burn you, but it can eat away at clothes and it can be lethal if you touched some and it somehow made its way into anyone's body.
If you meant the marine battery, I wouldn't mess with that either. Although it has liquid acid in it, the same sort of thing goes like with the Sealed Lead Acid batteries; the acid won't burn but is toxic and will destroy clothes. The only way to actually stop the acid is with neutralizer.
The lead acid inside won't burn you
bad advice.
I'm talking about desulfation using Ann ac current. Though that isn't physically taking apart the battery, it is still meeting with it in a way that could cause it to express.
By the way, I wish I was this guy:
https://m.youtube.com/user/Photonvids
Invictus3593
26-11-2013, 12:20
bad advice.
I work at the store, we literally split these same batteries open and take out the lead for recycling. It WILL burn if you don't take safety precautions, but its common sense to take them anyways.
Though there is sulfuric acid in the electrolyte, the water dilutes it significatly. Also, the sealed batteries (like the one in the picture) aren't filled with liquid like auto batteries. It comes out as a sort of blackish-grey powder, very much like alkaline batteries when they corrode.
It doesn't burn unless you don't take any safety precautions at all.
Opening a lead acid battery requires training and specific safety equipment, as I'm sure you are already aware.
35% sulfuric acid will burn exposed skin if not immediately washed off and can cause permanent eye damage if it gets in the eyes.
My concern is that your statement could be taken out of context and lead to harm.
For safety's sake I suggest you edit your posts to emphasize this.
Invictus3593
26-11-2013, 22:57
As I said in my first post in this thread, it is NOT a good idea to open or tamper with ANY battery. Let not my intentions be misconstrued, I was only trying to provide relevant information.
So Valcore,
Are you wishing to allowing the cart to charge up the batteries on the go? Or do you want it to be just plugged in to initiate charging, or a hybrid of both?
M. Mellott
27-11-2013, 13:09
Another suggestion might be to include chargers for rechargable drill batteries if your team uses cordless drills--we would never go to competition without our DeWalts!
Yeah! Also, it could be a possibility to power the battery drill from the cart battery, after the regular one runs out. It would only require a boost converter, but could save the team from running out of battery in the middle of something important. It would be nice to have 24 volt 24 ah (576wh) li-ion batteries to power the tools, because that is raw power, and long runtime!
Pauline Tasci
27-11-2013, 20:54
https://scontent-a-sjc.xx.fbcdn.net/hphotos-ash2/554370_4110003638195_1528943603_n.jpg
This is what i saw at 1717's open house,
its a movable shelf with chargers (i believe 7 ports each) on each side.
Pretty cool and functional.
MichaelBick
27-11-2013, 21:50
Ours has two shelves, each hold six batteries. The chargers themselves are Auto Meter chargers that can charge up to six batteries each (they are pricey, we had the assistance of our school district to pay for them). The whole thing is attached to a dolly.
http://dpea.smugmug.com/09-10-Robotics-Build-Season/Working/Electrical/DSCN0462/776255861_djgyf-L.jpg
Chargers can be found here: http://test.autometer.com/productDetails.aspx?ID=3&subid=5&productID=54&isKit=0
They are actually 6 port chargers.
Link to the whole thread here: http://www.chiefdelphi.com/forums/showthread.php?t=85479
Invictus3593
28-11-2013, 01:48
They are actually 6 port chargers.
Link to the whole thread here: http://www.chiefdelphi.com/forums/showthread.php?t=85479
These are great chargers. Had two at our store for three years running almost 24/7 charging 8D-size batteries. These will not dissapoint.
That's cool! Are they CC/CV/Hybrid? (Constant current/voltage/hybrid)
The charger is great, but the price tag is also great :confused:
I have a Harbor Freight charger, plugged in continuously, for years at a time, without a problem. It is slow, but it offers everything I need!
Invictus3593
03-12-2013, 09:18
Are they CC/CV/Hybrid? (Constant current/voltage/hybrid)
They are CV, I believe. They're like gigantic trickle chargers; if you run a deep cycle battery all the way down and hook it up to this, it would probably be back up to full in around 12 hours, depending on what deep cycle battery you use.
That is fast! How do you power it? Is there a deep-cycle battery connected to an inverter?
Invictus3593
05-12-2013, 11:25
That is fast! How do you power it? Is there a deep-cycle battery connected to an inverter?
I think you misunderstand. I use this at a battery shop where I work., I am not powering this off of other batteries, it is stationary. If you were to run this off batteries, my guess is you wouldn't be able to run it 12 without buying 8D size batteries or something ridiculous like that
Hugh Meyer
05-12-2013, 13:40
The battery charger information says it needs 220v input. That might be kind of hard to get in the pits. Is this the right link?
http://test.autometer.com/productDetails.aspx?ID=3&subid=5&productID=54&isKit=0
-Hugh
The battery charger information says it needs 220v input. That might be kind of hard to get in the pits. Is this the right link?
http://test.autometer.com/productDetails.aspx?ID=3&subid=5&productID=54&isKit=0
I'm wondering why it is 220v. Is it monumentally inefficient? I figure max output power is around 450 watts with all 6 stations going full bore.
Looking back through the thread I see the OP is from OR which throws a big wrench into the plans for a charging station.
Since we are in High School aux gyms for most of the events power to the pits is severely limited. We will be running on generator power for the pits and 5 or 6 teams will have to share 1 20a circuit. Because of this teams will be limited to the use of 2 chargers or one 3 station charger with no more than 2 batteries charging at a time. Also note that when the pits close power will be shut off to the pits so making a plan to take your batteries with you and charge them off site on Fri night is going to be a good idea.
Also it is important to note that you will not be allowed to plug ANYTHING into anywhere except your designated spot in the spider box in the pit.
Thad House
05-12-2013, 15:12
Looking back through the thread I see the OP is from OR which throws a big wrench into the plans for a charging station.
Since we are in High School aux gyms for most of the events power to the pits is severely limited. We will be running on generator power for the pits and 5 or 6 teams will have to share 1 20a circuit. Because of this teams will be limited to the use of 2 chargers or one 3 station charger with no more than 2 batteries charging at a time. Also note that when the pits close power will be shut off to the pits so making a plan to take your batteries with you and charge them off site on Fri night is going to be a good idea.
Also it is important to note that you will not be allowed to plug ANYTHING into anywhere except your designated spot in the spider box in the pit.
Really? I never would have guessed that power would be that limited. I'll make sure to pass that on.
Really? I never would have guessed that power would be that limited. I'll make sure to pass that on.
Yes that is what Kevin Ross announced during the most recent district model informational webinar.
It was announced as a blanket rule, however since we did not have limits on pit power at CWU and EWU in the past at those venues power may not be limited to 3-4 amps per team, but until there is an official ruling from Kevin otherwise, assume you'll be limited to that 3 amps at those events as well. I have no idea what the power situation might be at the OSU event since we've never had an official FRC event there before.
At the district CMP things will be as there were in the past at the Autodesk Oregon Regional since we will be in the same venue.
I can see some potential problems in the eliminations rounds at the district event. There will be no place to charge near the field and about 2/3 of the teams will be in the quarter finals meaning there won't be a lot of batteries to loan, nor teams with chargers that aren't in use to charge your batteries with.
Thad House
05-12-2013, 15:31
Would we be able to bring our own generator and run it in the parking lot? I could see a decent chunk of teams doing that if allowed.
Alan Anderson
05-12-2013, 16:18
We will be running on generator power for the pits and 5 or 6 teams will have to share 1 20a circuit...
That's not a lot of power. I assume you've tried to obtain the use of a generator large enough to support what teams are used to?
Mark McLeod
05-12-2013, 16:24
I figure our typical pit power draw as a team to be ~7amps.
You'd better hope no one plugs a vacuum cleaner in (~12amps).
Thad House
05-12-2013, 16:28
Doing the math puts charging 3 batteries between 150 and 220 Watts. Add a 50 watt laptop, a 30 watt cordless drill charger, and a few other accessories, plus losses and teams are gonna push that 400 watt limit real quick. I hope they can find a way to increase it, even if its only to like 6 amps per team instead of 4.
Doing the math puts charging 3 batteries between 150 and 220 Watts.
What did you use for charging amps and voltage for that calculation?
Thad House
05-12-2013, 17:01
What did you use for charging amps and voltage for that calculation?
Using 6 amps per battery and 12 volts gave 216 Watts. Not counting losses.
The 3 slot charger cannot individually change amp ratings, so it would most likely draw between 4-6 amps per battery, plus losses, puts the numbers right around 160-220 watts
I think it might be wise to bring a marine-cycle battery and a powerful inverter. Teams bringing all sorts of generators seems very inefficient and loud. Since teams aren't using power continuously, generators may be overkill without a battery to store and shut down the generator automatically! Also, a battery and inverter would probably cost less than a generator. Generators are for when you need LOTS of power, typically kilowatts. For every KG of gasoline, you can get a max of 5kw/kilo, which is the reason why most generators are rated for at least 750 watts continuous!
pwnageNick
05-12-2013, 20:40
While I did not read this entire thread, I skimmed through most of this, and I guess I'm just wondering why it is so important for this battery cart/station to be self-sustaining. You're supplied with power in your pit, specifically so teams can charge their batteries and driver station. I completely understand wanting to make an organized, well put together station for charging and storing your batteries, but the necessity for it running off a generator seems over the top.
Also, as far as making it able to drive, I see even less of a reason for this. Being able to drive the robot cart would make more sense then this, although I know I do not think that is a good idea, and I know many volunteers who have worked the queue at a competition would agree.
While I know that with all of the batteries, chargers, frame, etc. the cart will weigh a lot, I guarantee it will still be easy to push/pull.
https://scontent-b-iad.xx.fbcdn.net/hphotos-frc3/403045_349869605032431_582338502_n.jpg
Our team built a battery cart 2 years ago and it works great. Currently able to charge 9 at a time but could easily switch those 3 single bank charges to 2 three bank chargers. While it is heavy, we never have an issue being able to push it, and often times have other boxes on top of the cover when we are moving into our pit at the beginning of a competition.
https://www.facebook.com/media/set/?set=a.349869318365793.90542.109248172427910&type=3
There are more pictures of it at this link and I would be more then happy to ask any questions you have about it.
-Nick
While I did not read this entire thread, I skimmed through most of this, and I guess I'm just wondering why it is so important for this battery cart/station to be self-sustaining. You're supplied with power in your pit, specifically so teams can charge their batteries and driver station. I completely understand wanting to make an organized, well put together station for charging and storing your batteries, but the necessity for it running off a generator seems over the top.
Also, as far as making it able to drive, I see even less of a reason for this. Being able to drive the robot cart would make more sense then this, although I know I do not think that is a good idea, and I know many volunteers who have worked the queue at a competition would agree.
While I know that with all of the batteries, chargers, frame, etc. the cart will weigh a lot, I guarantee it will still be easy to push/pull.
https://scontent-b-iad.xx.fbcdn.net/hphotos-frc3/403045_349869605032431_582338502_n.jpg
Our team built a battery cart 2 years ago and it works great. Currently able to charge 9 at a time but could easily switch those 3 single bank charges to 2 three bank chargers. While it is heavy, we never have an issue being able to push it, and often times have other boxes on top of the cover when we are moving into our pit at the beginning of a competition.
https://www.facebook.com/media/set/?set=a.349869318365793.90542.109248172427910&type=3
There are more pictures of it at this link and I would be more then happy to ask any questions you have about it.
-Nick
That looks nice. I was thinking of overcomplicating things, and building a BMS (Battery Management System), to automatically pick the best battery, and to automatically do battery diagnostics!
pwnageNick
05-12-2013, 22:08
That looks nice. I was thinking of overcomplicating things, and building a BMS (Battery Management System), to automatically pick the best battery, and to automatically do battery diagnostics!
So basically what a Battery Beak does:
http://www.crosstheroadelectronics.com/Beak.html
We have one on a lanyard attached to the cart at all times. Works really well and is super simple to use. It is also made and sold by Cross the Road Electronics, which was started by Mike Copioli, who is very involved with FIRST. They also make the Talon motor controllers that many teams in FRC use.
-Nick
I was aiming at continuous monitoring and a readout updated a couple times a second!
pwnageNick
05-12-2013, 23:04
I was aiming at continuous monitoring and a readout updated a couple times a second!
For what purpose?
Don't get me wrong, I have over-complicated plenty of modules on robots in the past, but when it comes to off-season projects like a battery cart, where it is something that your team will use for a long time, it's better for your team to have a lot of things like that, instead of using all of its time and resources on a project that while partially useful, is also not helpful to a point and over the top.
That being said, if you have a ton of people, a ton of time, and plenty of money to make such an elaborate system, then full steam ahead. However I know most teams would benefit from having a battery cart as well as other items such as various other pit space items (i.e. a solid workbench with storage, a quality robot cart, a display that showcases its robot and chairman's qualities), or some robot prototypes that can be built upon and benefited from for years to come.
-Nick
Here's (http://devstuff.no-ip.biz:890/?page_id=58) my project page. It is kinda overkill, so beware! The way how I typically build things makes sure that they have a long lifespan. I use something like a Propeller and MCP3204s, to do all the sensing and other things! Even though I use open circuit boards, even decent-sized shards that fall into the controller won't damage it. It will stay shorted out until I fix it, then recover!
Would we be able to bring our own generator and run it in the parking lot? I could see a decent chunk of teams doing that if allowed.
If you are talking about using a generator in the parking lot and running a cord to your pit I would bet that would not be allowed.
That's not a lot of power. I assume you've tried to obtain the use of a generator large enough to support what teams are used to?
I'm just the messenger, I did not participate in deciding what size generator to rent to supply pit power. I can tell you that how running 5 or 6 pits off of 1 20a circuit at the WA Girl's Generation was taken into consideration when deciding the power needs. It did not present a problem there until someone plugged in their Leaf into one of the circuits.
I figure our typical pit power draw as a team to be ~7amps.
You'd better hope no one plugs a vacuum cleaner in (~12amps).
Something like a vacuum cleaner will not be allowed to be brought in and certainly would not be allowed to be used.
Doing the math puts charging 3 batteries between 150 and 220 Watts. Add a 50 watt laptop, a 30 watt cordless drill charger, and a few other accessories, plus losses and teams are gonna push that 400 watt limit real quick. I hope they can find a way to increase it, even if its only to like 6 amps per team instead of 4.
The current plan is to only allow charging 2 batteries per team at a time.
Again I'm just the messenger. If the power proves to be woefully inadequate the size of the rental generators will likely be revisited.
Al Skierkiewicz
06-12-2013, 07:45
A few things...
The six station charger is available in 120 volt version. We have used one for years and they work great. Why this one is listed at 220 volts is beyond me but it may be for an intended audience whose country is at 220 volts. The manufacturer is right here in Illinois. While the chargers are listed as 5 amps per station, they do not supply 5 amps continuously. The output current is varied for a variety of conditions dependent on cell voltage and time. These smart chargers switch charge current on and off while they are testing the battery condition.
I would suggest to event coordinators that teams be encouraged to remove their batteries each night to be charged back at their hotel. Please be advised that precautions need to be followed as charging batteries do have a chance of releasing hydrogen and on occasion, batteries have failed during the charging process. I recommend that charging be monitored by adults and that batteries be disconnected during sleeping hours. I would also like to recommend that event coordinators have a charging station somewhere for teams playing in finals.
Al, you know better than me, but I an just thinking, but isn't it safe to have a lead-acid slow-charging at night? I don't see any problems with it, especially when I have a battery on my desk that charges continuously! (Harbor Freight Charger)
Al Skierkiewicz
06-12-2013, 08:22
Dev,
I like to err on the side of safety and I have seen batteries self destruct at competitions before. I would not want a battery in a student's room start leaking or worse.
Dev,
I like to err on the side of safety and I have seen batteries self destruct at competitions before. I would not want a battery in a student's room start leaking or worse.
So talking about that, should I be keeping the battery in the garage instead of right next to my bed? I use it when I need sparks of power (100AH). Other than that, it is a paperweight
Al Skierkiewicz
06-12-2013, 08:27
There is a better choice somewhere between those two. Batteries don't like temperature extremes but next to your bed? Maybe we should talk....
There is a better choice somewhere between those two. Batteries don't like temperature extremes but next to your bed? Maybe we should talk....
Yeah! But talking about that, making sure the batteries stay at an optimal temperature in a cart is an important thing to do!
Mark McLeod
06-12-2013, 08:58
Sounds like they are renting something like a 16kw diesel generator for the school gym district events.
Maybe there are space limitations that preclude renting two, or maybe the power distribution system isn't there yet.
There are likely startup financial reasons for having to limit power and purchase $ (Northern Tool has a sale on a 25kW towable for $22,000).
Maybe that restriction will loosen up in seasons to come.
Non-battery powered pit tools will also be off the list (one 3/8" hand drill would be 4amps, the entire team maximum), so teams will just have to take better advantage of any machine shop facilities. I assume that there will be a mobile machine shop that travels around to each event?
Chris_Ely
06-12-2013, 09:25
Would we be able to bring our own generator and run it in the parking lot? I could see a decent chunk of teams doing that if allowed.
5.5.2.6 T11
At events, Teams may only produce FABRICATED ITEMS in the pit areas or provided machine shops, as defined in
the Administrative Manual, Section 4.8, The Pit.
Working in someplace other than your pit was not allowed in 2013, and I don't see that changing anytime soon for liability reasons.
My experience in FiM has been that there always was enough power for everyone. The only problems that I have seen were on Thursday night when the bugs were still being worked out.
Joke: At times, a large capacitor bank could be useful, especially when someone turns on a spot-welder, shutting down the breaker! :D
Now, back on topic, how much energy would the most energy-consuming machine used at competition take? Would it be a mill, consuming 500 Watts, drill consuming 60 Watts or something along those lines? Has anyone brought a UPS with them to give power as soon as power goes out accidentally?
pwnageNick
06-12-2013, 16:56
Has anyone really run into a situation where they did not have enough power in their pit? I mean seriously, are you running a concert inside your pit or what?
-Nick
Invictus3593
06-12-2013, 17:26
For powering the large charger mentioned before, it might be helpful to use one or two marine 12v batteries and this (http://www.lightinthebox.com/Power-Inverter-12v-220v-800w--SZC1303-_p68891.html?currency=USD&litb_from=paid_adwords_shopping&gclid=CPXh1uzRnLsCFYqPfgod9UMABg). If this doesn't work, I'm sure you can find one like it that has the right specs. Not very expensive either
Wow! That's cheap. I was looking at a 4kW one at Costco for about $200! Positive reps for you!
Alan Anderson
07-12-2013, 01:08
Has anyone really run into a situation where they did not have enough power in their pit?
Yes. A fuse blew at the Boilermaker regional one year, and lots of people had no power.
If teams are limited to 4 amps apiece, it's going to cause problems if anyone wants to run a shop vac. That's not an unheard of practice.
I'm surprised that the people setting up the regional don't bring in a 10 kW generator! That's weird because they probably know that there will be a great power usage. The only power problems we experienced were the lights going out during the Las Vegas regional, which I do not know about!
I'm surprised that the people setting up the regional don't bring in a 10 kW generator! That's weird because they probably know that there will be a great power usage.
Yash, you're going to go talk to the folks who run the Arizona Regional about how much it costs to run a regional, and how hard it is or isn't to get that funding. You're also going to talk about past Arizona Regionals in the Coliseum, same topic. (I'm hoping some of them happen to see this and go find you to make sure.)
Once you do that, you'll understand exactly why they don't bring in a much bigger generator at this time, even if they know there may be a huge power issue.
If it works out OK this time, then we'll all have been saying the sky was falling. If it doesn't, or barely works, then I'm sure that increasing the size of generator will be very high on the list of priorities for the next event.
Al Skierkiewicz
09-12-2013, 08:06
Yes. A fuse blew at the Boilermaker regional one year, and lots of people had no power.
If teams are limited to 4 amps apiece, it's going to cause problems if anyone wants to run a shop vac. That's not an unheard of practice.
This actually occurred because teams were using the upper limit of available power from the generator. Coupled with the warm temps that year, the electrical distro finally broke down and was too hot to go near for quite a while. It took out the pits and the FCS computers as well. Thankfully it occurred near the end of the competition day.
Putting in higher power generation carries higher distro costs and increased liability insurance. That is of course if you can find one locally.
Can't you hook up the pits to the cars? You may be able to generate a kilowatt!
Alan Anderson
09-12-2013, 11:16
Can't you hook up the pits to the cars?
Please elaborate. What do you mean?
You may be able to generate a kilowatt!
How far do you expect a single kilowatt to go? Consider the power used by a battery charger, an electric drill, a soldering iron, a laptop computer, a shop vac, etc.
Quite a bit over here in the US. We use 120 volts, so that would be equal to 8.3... Ah. For those on 240v, you would get 4.15.
Anyways, now I really think we are getting off topic so we should create a new thread, like "Power in the Pits"
Please elaborate. What do you mean?
How far do you expect a single kilowatt to go? Consider the power used by a battery charger, an electric drill, a soldering iron, a laptop computer, a shop vac, etc.
Your car's engine has enough power for many kilowatts (>100 kw), but the alternator and electrical system isn't designed for powering stuff. Some cars have an inverter built in, but their usually rated for only a few amps, so the alternator, charging system, and battery don't get damaged.
Teams also use a ton of power. We have an ancient computer that draws 450 watts while running video, three monitors, two pretty high power projectors, a few hundred watts of lighting, 10 robot battery chargers, and 3 drill battery chargers. We've also run all this plus a shop vac, sawzall, mini band saw, and mini bench grinder all at the same time. We don't typically run all this at the same time, but it's happened before. That's quite a few kilowatts.
Your car's engine has enough power for many kilowatts (>100 kw), but the alternator and electrical system isn't designed for powering stuff. Some cars have an inverter built in, but their usually rated for only a few amps, so the alternator, charging system, and battery don't get damaged.
Teams also use a ton of power. We have an ancient computer that draws 450 watts while running video, three monitors, two pretty high power projectors, a few hundred watts of lighting, 10 robot battery chargers, and 3 drill battery chargers. We've also run all this plus a shop vac, sawzall, mini band saw, and mini bench grinder all at the same time. We don't typically run all this at the same time, but it's happened before. That's quite a few kilowatts.
Car and light trucks (pickups and full-sized vans) have alternators that have current ratings in the range of 80 to 120A, depending on the vehicle, giving you about 1 to 1.2 kW of output power. That rating is only a peak rating for when the alternator is charging the battery after the battery was used to start the vehicle. It is very likely that the continuous current rating would be half of the stated peak rating or less so you will only get around 400 to 600 W continuous. No, the manufacturers are not going to tell you what the continuous rating is since they play the specmanship game.
All the motor driven power tools you use in your pits will have some sort of current rating printed on them if they meet the UL safety standards. The starting surge current will be several times (3 to 6 X) higher than that continuous current rating printed on the case of the tool. I blew out a 2 kW inverter running such loads off my trucks batteries during Hurricane Rita.
Al Skierkiewicz
10-12-2013, 07:39
Let us not forget the resistive losses of the wire at 12 volts. In vehicles you are talking a few feet at most while trying to bring that inside you are now talking 50-100 feet. Welding cable is needed to prevent the drop from being excessive.
In this case, wouldn't you step it up to 120/240 volts at the generator/battery/etc, and use the high voltage instead of the low voltage? Also, wouldn't you need gauge 6 wire or so, for the current traveling at 120volts?
In this case, wouldn't you step it up to 120/240 volts at the generator/battery/etc, and use the high voltage instead of the low voltage? Also, wouldn't you need gauge 6 wire or so, for the current traveling at 120volts?
No. Most wiring in your house is (probably) 14 gauge. Your microwave is probably 12 gauge. Wire gauge has a lot more to do with current than voltage.
While I did not read this entire thread...
Aaaaaaand here's why:
Looking back through the thread I see the OP is from OR which throws a big wrench into the plans for a charging station.
Since we are in High School aux gyms for most of the events power to the pits is severely limited. We will be running on generator power for the pits and 5 or 6 teams will have to share 1 20a circuit. Because of this teams will be limited to the use of 2 chargers or one 3 station charger with no more than 2 batteries charging at a time. Also note that when the pits close power will be shut off to the pits so making a plan to take your batteries with you and charge them off site on Fri night is going to be a good idea.
I love it when I can answer questions with material that was already said in the thread.
Al Skierkiewicz
10-12-2013, 11:59
Also, wouldn't you need gauge 6 wire or so, for the current traveling at 120volts?
#6 at 100 amps will drop 0.1 volt for every 2 feet of length. At 100 feet that is 10 volts. (remember you have to calculate for both the red and the black wire.) While at 220 volts that represents a mere 0.045% at 12 volts that is 83% drop in voltage. The wire size in a residential home is calculated on the voltage loss expected in a particular length and then fit to the breaker size. Many circuits in a typical house are 15 amp breakers fed with #14 wire. If you look at typical spec sheets, appliances are designed to run down to about 90 volts.
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