Best way to charge batteries

[Doc Wu]

+1 to what Al said.

I have found that the biggest cause of damage or reduced life of the batteries is ourselves.

The typical competition match is not bad for a good battery. You put a fully charged battery in the robot, go run the match, then come back to the pits and take the battery and put it on charge again.

This should not come even close to fully depleting the battery and it should only need a relatively short period of time to fully charge the battery again.

If you are killing your battery in a single match, maybe you should re-think that 6-CIM drivetrain...

What are the things we do that damage our batteries? Practice. Demonstrations. Testing. Any time you drive that robot until the drivers notice that the voltage is getting too low to turn, or your cRio is rebooting, you are risking damaging the battery due to over-discharge. We all do it. We all forget how long it's been in the robot.

What do we do to avoid it? Well, the obvious is change batteries more frequently. Let them cool, charge, then cool again before reusing. Less obvious is to try to equalize the use of your batteries. Rotate through them so that one battery doesn't get overused while another sees little use. Try to spread the usage around so that all the batteries are in equal condition and you don't end up with one that unexpectedly leaves you short in the middle of a match.

I have been keeping a set of batteries for my team that is for competition only. All the testing, demos, prototyping, etc. is done with older, but still good batteries. They tend to suffer the abuse, while the competition batteries live a sheltered life.

I test the batteries each year on a CBA III. I then use those results to decide what batteries will be kept and which will get recycled. Even new batteries get a test (time permitting). It's surprising how much variation there is with brand new batteries. They do seem to settle out after some break-in too.

My only problem with the CBA is it is time-consuming at 2-4 hours per battery.

We use a Battery Beak to confirm charge status. Or did until ours died.

We keep a record sheet for battery use during competitions. We use each battery only for one match, then use the next one, in order, until all have been used once, then start over at the beginning. Match number, time and battery beak data are recorded for each battery on the sheet. If a battery develops a problem, it can often be spotted on the sheet and removed from use. We bring some practice batteries for the practice field, testing, and charging up air tanks.

This practice maximizes the time for each battery between each use/charge cycle, allows time to cool, and equalizes the use of all the batteries.

This year, we took six brand-new batteries to competition, plus six of the best ones that were 1-2 years old. We also took six for practice use. We have six chargers. This is more than enough to keep up even in the final rounds. In fact, it's probably overkill. I say, if you stick to this type of plan you could get through a regional with six good batteries.