Battery Charging Station

[MichaelBick]

Originally Posted by yash101

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.

[yash101]

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]

Originally Posted by yash101

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]

Originally Posted by yash101

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.

Originally Posted by Mark Sheridan

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.

[yash101]

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]

Originally Posted by yash101

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.

[yash101]

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]

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.

[EricH]

Originally Posted by yash101

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.

[yash101]

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]

Originally Posted by yash101

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.

[Valcore]

Originally Posted by MysterE

Curious - Are you planning on using chargers that can also desulfate?

I dont think we are

[yash101]

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!

[Invictus3593]

Originally Posted by yash101

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!

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.

[Ether]

Originally Posted by Invictus3593

The lead acid inside won't burn you

bad advice.