Warming up the batteries
 

I'm definitely not used to this problem, being a 5th generation Floridian. We have retrofitted last year's robot to put a shovel in the ground and dig some dirt for the Ceremonial groundbreaking of a new high school in our team's school district tomorrow morning. We did a test run yesterday and everything worked fine, except that the driver said it seemed to be running very slow. I checked the voltage of the freshly charged battery and it showed under 12V no load. Oh by the way, it was 17 degrees F outside when we made the test run, and although the batteries had been stored inside the school I had them in the back of the pickup for the half hour drive to the site.

It's supposed to be up to about 50F tomorrow morning; If we warm up a fresh battery overnight and keep it warm until just before the big show, is it going to be good sitting for an hour during the speeches or do I need to wait until right before we power up to change it out?

Re: Warming up the batteries
 

Our drivers had a similar problem with the cold. I think it has to do with the physics of the battery.

The batteries are suppose to run at room temperature. That can mean different things. I would check the supplier's website for specific temperatures that they list.

Re: Warming up the batteries
 

I'd wait until power-up, just to be safe.

I've seen what cold can do to a NiCad (admittedly not a lead-acid) battery at "warmer" temperatures of around 20 F--went from about 3-4V or so down to 2V or thereabouts in a matter of minutes. Yes, it was being used, but that kind of drop is peculiar. To make matters more fun, it went back up after I went inside for a couple of minutes. The lead-acid(?) 12V batteries were somewhat discharged already, but refused to work right until put inside and charged, so we grabbed a car to supply the power needed.

At 50 F, you might get away with it, but I'd keep it in the vehicle until right before you need it.

Re: Warming up the batteries
 

In other applications I've had good luck with a wrapping of a nice thick blanket and a handful of the chemical hand warmers.

Re: Warming up the batteries
 

I'm just waiting for either Ether or Al to chime in.

Re: Warming up the batteries
 

We had our 12v batteries running 201 and 245's robots in a parade 2 weeks ago (Michigan suburbs north of detroit). It was freezing out and they had been sitting out all morning so they were at 32 F. The batteries tested at above 12v before packing (the warm school). While in the parade, they were slightly less but the robots ran the whole 30 minutes on 3 batteries.

The robots were sluggish, but nobody is going to question you changing the batteries before you start. I mean you need to take 5 min to turn it on anyway right?

I would not worry about 50 F weather. Its not their prime but it is alot closer the the optimal performance zone.

Re: Warming up the batteries
 

Based on experience using the FRC batteries in a previous robot we built, as long as you keep the batteries somewhere warm until a few minutes before they're needed, you'll be fine in 50F weather. The large quantity of lead in FRC batteries will maintain a sufficient core temperature until you start using them (after that point, heat from the chemical reaction usually keeps them warm enough to keep going).

If the temperature is closer to (or below) freezing, wrap the batteries in hand warmers and insulation.

Re: Warming up the batteries
 

We were involved (and organized) this event as well.

Using 2007 robot, without the drivetrain (1 FP, 2 Globe, 1 Banebots, and the compressor total), we ran on 3 low batteries (one was questionable, the other two were not fully charged but decent at 11.9-12v no load). All of the batteries were sitting on the truck with the robot for a few hours before the parade. The elbow joint (2x Globe) will not run on less than 11v, so we could deplete the batteries less than 201 and 245 could.


It was cold enough for one of our plastic rollers on the claw to break when closing. It was, however, very thin, due to extensive lightening efforts.

However, unlike 201 and 254 (which had cRio-based 2009 robots), our 2007 IFI robot could boot in under a second (on tether). We changed the battery during the parade without issue.

Re: Warming up the batteries
 

Without getting into the physics, "What Art Said" and you'll be fine.

17F is hard on a lead-acid battery, and even harder on a gel cell. Less than half capacity.

Re: Warming up the batteries
 

I agree, Art hit the nail on the head. Just leave the battery on the floor of your truck until you need it. Don't forget the lube in your robot is not made for low temps I bet and that will be as much of an issue.

Re: Warming up the batteries
 

FWIW think about it this way:

1. All batteries produce energy and power through a chemical reaction.
2. In order for a chemical reaction to occur atoms or molecules of the two reactants must interact.
3. Temperature is the average kinetic energy (i.e. speed) of the random movements of atoms/molecules.
4. When a battery is cold its molecules are moving slower than if it was warm.
5. Slow moving molecules collide/interact less frequently with each other, making reaction rates in the battery go down.
6. Slower reaction rates in the battery mean that the battery cannot produce electrons as fast as it could when warm, so it performs worse.

50F probably isn't that big of a deal, but warmer is better.

Re: Warming up the batteries
 

Maybe some one here can help us. Our battery will drop from 12-13 volts to 9-8 in 1 minute of just being plugged in no matter what the temperature is. This happens with all of our batteries and we can't figure out why. Temperature doesn't affect it and neither does the amount of time that is charging. We have done research to solve our problem but have had no luck. We are afraid that we might have the same problem next year because we can fix it if we can't diagnose it! Can anyone help? Thanks

-Ally
316

Re: Warming up the batteries
 

I agree with all of the battery comments. You should be fine.

Two more aspects of cold ambient affecting FRC robots:

1. The first is if your robot utilizes latex tubing. Latex changes its springlike properties dramatically at low temps.

2. The second is to be sure that the ambient temp and/or robot temp is well above the dew point. The electronics, if cold, can condense moisture from the air and can make things interesting.

Regards,

Mike

Re: Warming up the batteries
 

Ally,

It sounds like you may have a faulty battery charger.

Mike

Re: Warming up the batteries
 

^This.

Or some part of your electrical system is damaged. Or the batteries are just getting old. Does this happen to every robot it's plugged into or just one? How old are the batteries? Any idea how many charge cycles they have been through? Ever load-tested any of your batteries?

Re: Warming up the batteries
 

Ally,
You have left a lot open to question. Does the battery drop with the robot turned on but not moving? It is normal for a battery to read 8-9 volts under load (while the robot is moving) after a minute of operation particularly if you are running the compressor and using a lot of air. When you stop moving and the compressor turns off, does the battery come back to 11-12 volts on your dashboard? Again this is normal.

If the battery draws down to 8-9 volts with nothing else running and stays there or gets worse, then you have a short or bad component on the robot. Start by pulling all the breakers and then putting them back in one at a time to determine which device is drawing the battery down.

Re: Warming up the batteries
 

We only have the one robot because we have to carry previous parts over to new robots. Could it be possible that all 7 of our battery chargers are bad? We have batteries dating back to 2006, but we have the one from every year. We haven't load-tested it. How would I do that?

The battery drops just from the time we take it off charge, put it in the robot, and turn it on. It will drop to an unfunctionable 6ish by the end of a match. The compressor takes a lot, but our battery dies just by plugging the robot in and not even turning the robot on. At comps we plug in the battery then walk to the field and by the time we get connection it has already dropped from 12-9 and we can watch it drop by not even moving(without the compressor running)(and we'll be disabled). But our volt meter will read something along the lines of 13 before it goes in the robot. And then once the voltage drops it does not come back up. We only had this problem during off-season competitions and practice this year, but never before that.

Thanks for your help!

Re: Warming up the batteries
 

It seems most likely that there is a problem with your robot's electrical system. I would disconnect everything: the battery, main breaker, all the power distribution board breakers, etc. Measure battery voltage, connect ONE THING ONLY, measure battery voltage again, and repeat until you find out what component is draining your power.

If the battery is draining while just sitting there it may be a fault with the main breaker, Anderson connector, or all of your chargers/batteries were exposed to the same damaging conditions.

Re: Warming up the batteries
 

I'll have to try it. Thank you so much!

Re: Warming up the batteries
 

Those symptoms suggest either that your robot is drawing significant current when it should not, or that something bad has happened to all of your batteries. Did they get frozen or baked at some point? (A frozen SLA battery will not have much capacity afterward, especially if it was discharged at the time.) Do you have one charger that has failed and keeps pumping current into fully-charged batteries? (We boiled a bunch of batteries that way a few years ago.) Does someone on your team have a habit of carrying them by the wires? (That is very bad.)

The possibility of faulty robot wiring is actually the preferable option here. Without a battery connected, use an ohmmeter to look for (and with luck, find) a connection between the power connector and the frame of the robot. Or you might just be getting physical contact between the battery terminals and some metal structure.

Re: Warming up the batteries
 

Ally,

The chances that you have a bunch of bad battery chargers is very unlikely.

I agree with the suggestions of turning on one thing at a time to identify a fault.

Another possibility: I have seen are loose connections at the battery causing high resistance and large voltage drops. Last year, I had a team at WPI with bad connections on all of their batteries...

Regards,

Mike

Re: Wtteriarming up the batteries
 

Ally,
There are a few answers here. The batteries that are from previous years, 2007 or earlier have likely reached their maximum life. If they cannot hold a charge, it is time to recycle them. Our batteries have a useful life span of a maximum of 400 charge/discharge cycles. If they are run hard (drained in one match) you can expect that to be much less. If you have used them for a significant number of demos and off-season play then it is likely that even this year's batteries could be at the end of their life. A battery load tester can tell you for sure. A voltmeter cannot tell you anything about the battery without a load. The one I recommend is the CBA-II from West Mountain Radio. It is expensive but worth every penny. it even allows you to test the battery and overlay it with last year's test of the same battery to track age differences. We have been using mine since 2004.
For those that might be wondering, yes batteries can fail right out of the box. Dropping, holding by the wires and poor storage can kill batteries. Over charging, higher than 6 amps, will also kill a battery no matter how much you think you are monitoring it. With AGM batteries, the higher voltage encountered with high current chargers, can punch through the glass mats and cause hot spots inside the battery.

Re: Warming up the batteries
 

Alright, I'll check these things too, but I won't be able to get into our workshop until January so it'll take some time to find out what it is. I really hope we can find the problem before it accidently gets recycled and put on our new 2011 robot!

Re: Warming up the batteries
 

We have tried just having it plugged into one thing at a time. We tried all this during the elimination rounds at Ramp Riot this year. We currently have one or two batteries that actually work. The 2010 battery we got is one of the worst ones. I don't remember exactly which battery works the best, but it was the only one consistently working for us.

Re: Warming up the batteries
 

A sharpie is a good thing to have on you at all times. Mark the suspect batteries as "practice only!" Mark your new ones with the date you opened the box and put them on the charger. Mark the side or the top, never the bottom. You will wear off important info if you mark the bottom.

Sammy,
Remove all the snap action breakers and then see what happens. The only thing running should be the Crio and the wireless access and the camera if you have one. If you have a camera, pull the plug on the bottom. If the battery doesn't discharge, then add two breakers that feed your drive train and see what happens when you drive. If the battery stays up, add two more breakers and repeat. Typical electrical problems are frayed connections at the Crio power input connector or the power output connectors on the PD. The same is true for power feeding the sidecars and Crio interface cards. Check all the wiring on the PD as this is another area where a frayed wire will contact and adjacent lead.
Another common problem is through the camera which has a power supply common to the camera case. Plug the camera in last if you have one. When you are telling us the battery is falling to 8-9 volts is that reading on the dashboard/Classmate or with an actual voltmeter across the battery terminals? It is not uncommon for there to be a failed 50 amp battery connector on the robot side that could be dropping the voltage. A bent contact, a poor crimp, a damaged terminal on the PD all could give the effect of low voltage to the robot.

Re: Wtteriarming up the batteries
 

I believe we have tried using a batter load tester. I'm not totally sure, but I think so. As Ally said, we are unable to get into the workshop until January to test the batteries any further.

Thanks everyone for all these ideas! We've been kinda lost about what is wrong and where to go from there, but these should really help us out

Re: Warming up the batteries
 

Each battery has a number (as well as the year we got them) and we are planning on keeping a record of the voltages of each battery/how they ran when we tested them.

Re: Warming up the batteries
 

In 2008, we did 2regionals and a scrimmage before atlanta, and had the battery mounted on it's flat side in the robot. We then lost two matches at Atlanta because two of the six batteries we had been using would die during a match. They would read 13volts on a meter before a match, but under load it dropped to 6 volts or so. We eventually figured out that one or more of the glass plates within the battery must have cracked or have been compromised. We now use a 50 dollar load tester from napa auto parts to make sure the batteries are still ok when at competition.

New students see those batteries as industructible heavy objects and don't realize how careful they need to be with them. I also recommend mounting them as vertical as possible to reduce the stress on the plates inside.

Re: Warming up the batteries
 

You have any of several issues:
1. The chargers are all bad (unlikely)
2. The batteries are all bad (very likely)
3. The robot has a fault (possible)

You've read several suggestions to eliminate #3.

#1 is indeed unlikely, but possible. After a full charge (as indicated by the charger) measure the battery voltage with a multimeter. A normal reading for a battery just off the charger would be over 13.5 volts. Let the battery sit for a day, to eliminate the 'surface charge' and a normal reading should 12.6 volts.

#2 is easily determined with a load test. Al's recommendation of a West Mountain Radio CBA is excellent, but they are not free.

Instead, take about 10 feet of #10 wire (or 8 feet of #12), which should be about 1 Ohm. Measure the length of wire with an Ohmmeter (be sure to comensate for the resistance of the meter's test leads) to verify about 1.0 Ohms. (A high-wattage 1 Ohm resistor (25 Watts capacity) will do as well)

While measuring the voltage across the battery terminals, connect the 1 Ohm load (the wire or resistor) also across the battery's terminals. Count exactly 15 seconds. Write down the battery voltage at the 15 second mark.

A Very Good battery will read over 10 volts. An OK battery will read over 8.5 volts. Bad battery will drop below 8.5 volts. (NOTE: These numbers are debatable, but that's what I use).

If in 15 seconds with a 1 Ohm load your batteries all drop below 8.5 volts, and start above 12.5, they're bad. Buy new ones.

What causes a Lead-Acid battery to go "Bad"? Other than usage, sitting in a discharged state (terminal voltage less than 12.4 volts) for any period of time. Like over the summer. This kind of battery loses 50% of its charge in 90 days. On our team, we make sure they don't go more than 60 days without getting charged. Even then, we lose 3-4 batteries each year.:(

Re: Warming up the batteries
 

OK Sammy,
We will be waiting for a report in January. There is a possibility that you have one or more failed chargers and that in the normal course of events, all batteries have been touched by the bad charger. That is unfortunate but should not be ruled out. I am going to guess that the batteries have been used often and are just dying of old age.
Doug, the glass is a woven mat between the plates so there is really nothing to break. The lead plates can become dislodged with abuse and break off the common terminal inside a cell. In this case, the battery will test normal even with a momentary load tester. The CBA will show this damaged cell by a drop of 2 volts after a period of time. Black in the attached plot is a normal (2 year old) battery showing 16 amp hour capacity, the blue shows a two cell failure, green shows a single cell failure and the red shows the signs of intermittent plate connections within a cell followed by several cell failures.

Re: Warming up the batteries
 

Don, any advice on safe (ie sparks and heat) and effective (ie minimize extra resistance due to poor connection) ways to do this ?

Also, where did the "10 volts after 15 seconds at 12 amps" rule come from?

According to the datasheet, a new battery should still read 12 volts after 16 minutes at 18 amps.

Re: Warming up the batteries
 

Let me give a short thanks to Al and another plug for the CBA (computerized battery tester).

http://www.westmountainradio.com/pro...oducts_id=cba3

We've used this at his suggestion now for 3 years, and even gone so far as to rate our batteries 1-10 based on their tested capacity. It takes a while, but is definitely worth it to weed out the batteries that are simply worn out.

Re: Warming up the batteries
 

He said to measure during discharge. The datasheet values are after discharge has stopped.

Re: Warming up the batteries
 

Joe,
As the datasheet does not give all the measurement specs, I would have interpreted this as load curves with calibrated load resistors. Generally, with the load removed the terminal voltage would rise. With a high impedance voltmeter, there is no voltage dropped across the internal impedance of the battery.
I interpreted Don's #10 wire test as a go/no go test for his team, not a definitive battery test.

Re: Warming up the batteries
 

"He said to measure during discharge." He did indeed. It would still be informative to know where the "10 volts after 15 seconds at 12 amps" rule came from. Is this a home-grown FRC metric based on experience? Or is it published somewhere?

"The datasheet values are after discharge has stopped." The datasheet didn't mention that fact anywhere. I guess this must be a common understanding among those who work with battery specs? It would be interesting to know how long the testing is paused at each datapoint to allow the voltage to rise before recording it. Perhaps that's part of some battery-industry spec. Also, question for Al: in the CBA graph you posted, are the voltages open-circuit voltages or are they volts under load?

Re: Warming up the batteries
 

To my knowledge they are under load as the CBA is merely an air cooled variable resistor with a USB interface.

Re: Warming up the batteries
 

The graph you posted in this thread was for 1 amp load. Do you have a 12 amp graph (of the FRC battery) you could post?

Also, as I understand it the CBA is computer-controlled. Is it possible that it is momentarily opening the circuit before taking each voltage reading?

Re: Warming up the batteries
 

The curves are generated at 7 amps or about 0.5 C (see curve menu at right side of graphs). From the CBA webpage...
"Unlike a resistor load it has an electronic constant current load that is controlled both with software and electronics."
I don't think taking a reading after removing the load will give any valid information. I do not recommend that anyone use a voltmeter alone to evaluate the state of charge on an SLA battery. The input impedance of modern voltmeters is sufficiently high to prevent an accurate reading across the internal impedance of the battery. As this "resistance" changes with battery age, temperature and state of charge, the load test will tell exactly what the battery is capable of delivering in a curve that can be compared with both the published battery data and with past tests of the same battery. The one amp shown was generated when I overlayed the four previous tested battery curves onto a single page within the program.

Re: Warming up the batteries
 

- Don suggested applying a 12 amp load for 15 seconds and measuring the voltage under load. Above 10 volts is Very Good. 29

- Ether cited the battery discharge graph in the datasheet for the FRC battery which shows 12 volts after 16 minutes at 18 amps. 31

- Joe stated that the voltages in the datasheet graph are taken open circuit. 33

- Al stated that he believes the datasheet graph is showing load curves 34, and that to his knowledge the CBA graphs are load curves too. 36

- Al's 7 amp graphs show a healthy battery still reading over 12 volts (under load) after 43 minutes at 7 amps. Even a very sick battery (blue line) still reads over 12 volts (under load) after 17 minutes at 7 amps. 30


Can somebody help sort this out ?

Re: Warming up the batteries
 

I think you're off by a factor of 100, Don. Isn't ten feet of #10 wire actually more like 10 milliohms?

(A single ohm would only draw about 12 amps, which isn't nearly enough to give useful information about the health of a battery after just fifteen seconds.)

Re: Warming up the batteries
 

I know that this can be confusing so I am going to make a stab at this. The MK battery charts are generalized, guaranteed specifications for a new VLRA battery. The company has set these standards for the entire line and the graphs are plotted for Amp Hour vs discharge current rated in C where C = the rated discharge rate in amp hours. For our battery C=18AH. The MK Company charts are published on their website for VLRA batteries. The curve we have been looking at is a converted chart where the C values have been converted to discharge amps. .1C=1.8 amps, .5C=9 amps, etc.
For Team 111, the CBA tester is then set to it's maximum current (for this model) of 7 amps. Each battery, each year, is then tested at the beginning of the build season and the curves saved for each battery. If a battery tests out at 15 AH or above for the test, it is considered good enough for competition. Anything under is marked for "practice only". If there appears to be cell failures as shown previously, the battery is recycled. Failures of this type can be frustrating to team members and I fear can cause damage to chargers. I might be persuaded to run higher current testing if I were to purchase the higher current model CBA but I would not test at anything above 18 AH rates to maximize battery life (charge/discharge cycles). This testing does duplicate published company specs and curves leading us to group like batteries as healthy enough for competition.
As noted, even bad batteries can show normal terminal voltage before a cell(s) fail. Don's test, however, would also fail when testing a similar battery.
In Don's test, as pointed out by Alan, the current is much more than 12 amps. It is however within the realm of current drawn during match play. By performing this test, Don's team has been reasonably sure that the battery will survive a two minute match. I would agree, but point out that max battery life will suffer. The kind of current drawn during this test is beyond the current drawn by most FRC robots during a similar time period. An FRC robot might draw this current in a failed autonomous run where the robot is pushing against a wall or other barrier for the entire auto period. It is possible to draw this much current on an FRC robot as the 120 amp breaker will not trip. It is possible to draw up to 600% of the rated current for several seconds without a trip on this breaker.
Don and I are both amateur radio operators and a familiar term for us "key down". In our hobby we relate "key down" time to the average battery usage of portable operation. It is usually calculated by a percentage of actual transmit time (high current) and receive time (low current) operation. Many of us have discussed using this analogy for FRC robots but unfortunately, there is no standard robot for which to make predictions. In either case, both of our testing, although possibly flawed, can predict with some certainty that a battery so tested will survive a two minute match. Simple voltmeter testing, very high current load testing (car battery handheld load testers) for seconds, and short driving tests will not guarantee a battery will last a two minute match plus auto.
It is also a problem when people quote sections of the manual out of context. For instance, the maximum current specification on this battery is 720 amps for several seconds. Note that terminal voltage is not specified here. 720 amps would drop nearly 8 volts across the internal impedance of the battery. It is why the designers of the PD made two boost buck regulators to feed the Crio and wireless access point. High current demands would shut down these two critical systems without the additional power supplies rendering the robot useless for most of the match.

Re: Warming up the batteries
 

Updating previous post with new info:

It was apparently a typo. Don meant 0.01 ohm, not 1 ohm. [edit]Don did not mean 0.01 ohm. see his new post.[/edit]

But with 10 volts across a 0.01 external resistance, the load would be pulling 1000 amps... and that raises two problems:

1) Fifteen seconds of that could potentially damage the battery or lessen its life. It would also probably burn up or damage a 25 watt 0.01 ohm resistor.

2) The battery can't supply 1000 amps at 10 volts. Its internal resistance is too high*.

Perhaps the resistance of the copper wire is increasing due to heating. Let's say the wire gets boiling hot (100C). That's a dT of 80C, which would increase the wire's resistance from 0.01 ohm to 0.0132 ohm. At 10 volts, that would be 758 amps. Still too high.

Perhaps the test depends on additional external resistance, maybe from a switch that is used to complete the load circuit? (I hope someone is not just holding the wires and jabbing them into the battery terminals :eek:)

Don, do you guys have a clamp-on ammeter? Could you record the actual current draw next time you do this test and post the results?


Bottom line: Don's test is certainly severe enough to challenge even a brand-new battery. I worry a bit about safety, though, and battery damage. Do not attempt this without competent training.

Still not 100% resolved, but I think this is one of those rare times that Joe is mistaken.

All true, I think.


*the internal resistance of the battery drops as the temperature increases, but not enough to allow 1000 amps without damaging the battery.

Re: Warming up the batteries
 

OK, Maybe this'll help. Maybe not.

I meant 1 Ohm, not 0.01 Ohm. 1000 Amps would be nifty, but impractical.

Spark-free, safe & effective uses the 120A main breaker to bring the load online. We wired everything (including voltmeter leads) to a PowerPole battery connector for simplicity. I am using a 1 Ohm, 125 Watt resistor I 'happened to have'.

Alan, of course you're correct. if 10 feet of #10 had 1 Ohm, my house would've burned down years ago. And none of the power outlets would deliver more than, say, 20 or 40 volts AC. I just wrote what came to mind, and obviously I was off by at least 2 orders of magnitude. :o And, since 1000 feet of #10 isn't usually just hanging around most shops...I'll just suggest finding a 1 Ohm resistor somehow.

Ether, you asked where did those numbers come from? Empirical results over the years, specific to FRC batteries. These are based on recommendations from the Battery Council International (BCI), but they're dealing with automotive batteries being tested at somewhat higher rates and so their data doesn't directly apply here.

Lastly, a comment on the glass mats used in "Absorbed Glass Mat" technology batteries: Think of compressed fiberglass insulation, that's what the mats look, feel and taste like.

Re: Warming up the batteries
 

Of course, you all know beyond a shadow of any doubt that I am an idiot.

I re-read Alan's comment, and of course: 1 Ohm (12 A) shouldn't bring any FRC battery down to 10 volts any time soon. I mean, how would we survive a 2 minute match?

I just wish I could delete all I wrote in this thread and just start over.

I promise to rely less on memory and focus more on reality in the future. I am mortified and embarrassed.

Don

Re: Warming up the batteries
 

Of course, you all know beyond a shadow of any doubt that I am an idiot.

I re-read Alan's comment, and of course: 1 Ohm (12 A) shouldn't bring any FRC battery down to 10 volts any time soon. I mean, how would we survive a 2 minute match?

I just wish I could delete all I wrote in this thread and just start over.

Ether, I'd best say that I just pulled those numbers out my (you know). They're not even that good. What the #311 was I thinking?

I promise to rely less on memory and focus more on reality in the future. I am mortified and embarrassed.

Don

Re: Warming up the batteries
 

Boy Don, it's been a day and a half since you posted that and noone has stood up for you yet? I guess you know who your friends are.....

I'm really glad you threw some ideas on the table, regardless of their accuracy. When I first posted I was looking for and expecting a short answer, but looking at the details that teams are going through to test out batteries has really got me thinking. Like a true M.E. I just figured it was a box of electrons with no moving parts and how much could possibly go wrong? I'll never take the batteries for granted again.

Re: Warming up the batteries
 

You haven't see the private notes of encouragement :-)


Me too. It inspired me to think about this and do some research.

Re: Warming up the batteries
 

Nah, Don is just mature (see sig) we all have our moments and we all are still learning. Cue cheesy sitcom ending :p

Re: Warming up the batteries
 

Thanks folks. :o

But the bit about using the master 120A breaker as a switch and wiring it up is all true. Honest! :ahh:

Re: Warming up the batteries
 

You might as well use it as a switch, 'cause it will never trip during the course of a match, unless you're drawing 150A the ENTIRE TIME.
http://www.bussmann.com/pdf/15e0468b...391d3f173b.pdf