Battery Best Practices

[AcesJames]

1) - 7 or 8 competition batteries, 1 "pit test" battery for testing code, charging pneumatics in the pits, etc.

2) - One triple charger and two single chargers (5 batteries max charging at once).

3) - Our EE mentor spends about a week discharging and recharging batteries before competitions start. He reconditions the batteries, and then load tests them. Those which do not pass the competition load test become "pit test" batteries, and they are replaced with brand new batteries for competition use. All passing batteries are then labeled "Competition OK 2012"

4) - We label our batteries by number, and keep a running list of how often they're used during a competition, and what their individual voltages are when they're finished charging. We put 1 charged battery in the robot, take 1 extra charged battery on our cart to the field just in case, and have at least 2 charged batteries ready to replace them in the pits.

[Ernst]

We tested our batteries this year as follows:

1. Acquire battery
2. Plug battery into dc to ac converter
3. Attach volt meter to leads
4. Plug Halogen bulb into converter
5. Turn on converter
6. Turn on bulb
7. Record Battery start voltage
8. Wait for battery to drop below 10 volts
9. Record time taken
10. Label battery accordingly

It took awhile, but worked fairly well for reheating pizza.


Also,

Originally Posted by fox46

Both the teams I mentor use these: http://www.tecmate.com/u_accumate_pro5.php

What are the approximate dimensions of this battery charger? We're considering building a new battery cart (wooden box containing chargers, slots for batteries, and AndyMark battery plugs. On wheels.) and this seems almost perfect.

[Ether]

Originally Posted by chadr03

We are a team on a bit of a tight budget looking into a load tester. Does anyone have any experience with the attached relatively cheap tester from Harbor Freight?

http://www.harborfreight.com/100-amp...ter-90636.html

The Genesis NP18-12R battery (2012 FRC KoP) datasheet¹ indicates that it is rated up to 150 amps, so in theory you could measure it with a 100amp load tester, but:

1. The datasheet does not list any manufacturer specs at that high discharge rate, so any assessment based on testing done at that rate could only be relative to other batteries tested the same way.
   
   
2. In the wrong hands, testing at 100amps could damage the battery or be a real safety hazard.

Use something else.

¹ http://www.batteryplex.com/sheets/NP18-12R.pdf

[Ether]

Originally Posted by ZehP

We tested our batteries this year as follows:
...
2. Plug battery into dc to ac converter
...

FWIW you can buy 300 watt 12 volt bulbs at a pool supply store. Not the safest thing to do either.

[Ernst]

Originally Posted by Ether

FWIW you can buy 300 watt 12 volt bulbs at a pool supply store. Not the safest thing to do either.

We just used a shop light that we had lying around.

[Ether]

Originally Posted by ZehP

We just used a shop light that we had lying around.

Was the DC to AC inverter lying around too? Or did you have to purchase that for this use?

[Captaindan]

Originally Posted by chadr03

We are a team on a bit of a tight budget looking into a load tester. Does anyone have any experience with the attached relatively cheap tester from Harbor Freight?


http://www.harborfreight.com/100-amp...ter-90636.html

yes ours is still going strong after 2 years and an anderson connector soldered to it

[Ether]

Originally Posted by Captaindan

yes ours is still going strong after 2 years and an anderson connector soldered to it

How long do you leave the 100amp load on, and what is your voltage criterion for pass/fail?

[pwnageNick]

FRC Team 2949 PWNAGE just finished building a new battery cart. It consists of 12 batteries, 9 charger banks, a BatteryBeak, Spill Kit, 2 DeWalt chargers, extra AndyMark Battery Clips, and a removable lid. Some pictures below show the setup.






The DeWalt chargers and spill kit still needed to be added since these pictures were taken. The DeWalt chargers are mounted on the plate on the top middle of the cart (in-between the chargers). The spill kit goes under the 2 3-Bank chargers. Eventually with some more fundraising done we will switch out the 3 1-Bank chargers for 2 more 3-Bank chargers.

I would be happy to answer any questions about it. I had just uploaded a couple of pictures of it to CD a couple of days ago, but apparently hey still haven't been approved... anyway let me know what you think.

More pictures can be found at our fb page (Like us!):
http://www.facebook.com/pages/pwnage...09248172427910

-Nick

1. All of them (we only have 4)
2. 2, maybe? (we only have 1 right now)
3. We plug them into the charger to see it they're charged (no Beak yet)
4. Nope
5. Charge them always. They run out of juice super fast.

[Al Skierkiewicz]

Nick,
Can't wait to see it.

[cheesepuffgd]

1) My team takes all of our batteries from the last 3 years to competitions
2) My team takes a "battery cart" that has 4 chargers connected to a single wall outlet
3) My team puts each battery through a cycle of discharges over decreasing loads using the incandescent lightbulbs also on the battery cart. this conditions the battery and can restore some lost capacity. The battery cart is fully automated with an Arduino microcontroller and can condition 2 batteries at once. for electrical schematics and datasheets and eventually source code for the Arduino, search "team 955 battery cart" on google and select the first option.
4) besides charge them?
5) don't store batteries partially discharged for long periods of time.

[Ether]

Originally Posted by cheesepuffgd

My team puts each battery through a cycle of discharges over decreasing loads ... this conditions the battery and can restore some lost capacity

Can you provide a link to an authoritative source for a technical discussion of this phenomenon?

[Al Skierkiewicz]

Originally Posted by cheesepuffgd

1)
3) My team puts each battery through a cycle of discharges over decreasing loads using the incandescent lightbulbs also on the battery cart. this conditions the battery and can restore some lost capacity.

5) don't store batteries partially discharged for long periods of time.

I suspect the attempt here is to remove some sulfation on batteries that have sat around for a long (many months) time. Batteries self discharge over time so it is impossible to store partially stored batteries. (see battery sheet on self discharge specifications) However, it is best to charge batteries before storage and keep them in a temperature controlled environment. i.e. Don't allow them to winter in an unheated garage or to sit in an closed shed during the heat of summer.

[tsaksa]

Originally Posted by Al Skierkiewicz

I suspect the attempt here is to remove some sulfation on batteries that have sat around for a long (many months) time. Batteries self discharge over time so it is impossible to store partially stored batteries. (see battery sheet on self discharge specifications) However, it is best to charge batteries before storage and keep them in a temperature controlled environment. i.e. Don't allow them to winter in an unheated garage or to sit in an closed shed during the heat of summer.

I have also known of some people doing this with brand new batteries since SLA batteries reach top performance after a few proper charge discharge cycles. A friend of mine actually holds a world record for an electric vehicle race, and does things like this. The random discharge cycles a new battery might experience are not likely to be ideal in conditioning a new battery if left to chance. I have never tried this though because from what I understand the benefit is modest at best, and doing this to incorrectly can actually increase sulfation and other battery problems. I might try it someday, but right now it has not made it very high up on the priority list.

What we do right now is to never deeply discharge any battery. We try to always get a battery onto the charger immediately after use to avoid sulfation. We also store the batteries in a cool but not cold location and top up the charge regularly (at least monthly, preferably weekly) on any unused batteries. And our newest competition batteries do not get used for driver testing or software development where they can easily be over stressed before anyone notices. Someday we will try to increase our knowledge of and attention to proper battery care. But for now just a few basics seem to have made a significant difference for us.