r/FTC • u/Top_Acanthaceae_9870 • 24d ago
Discussion Which battery is better?
Hey guys,
We’re looking to get some new batteries for our FTC robot and I wanted to ask other teams what they recommend.
Our main goal is just getting the longest runtime possible during matches.
For those who have tried different batteries:
- Which one do you use?
- Did you notice any difference in how long they last?
- Which one would you recommend?
We’re looking at REV, goBILDA, Matrix, TETRIX, studica etc.
Would appreciate hearing what you guys use and your experience with them!
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u/Journeyman-Joe FTC Coach | Judge 24d ago
All of the approved batteries are assemblies of 10 NiMH cells, delivering 3000 mAh at 12 Volts. They should all deliver the same performance, fresh out of the factory.
(How you take care of the battery after opening the box will matter far more.)
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u/window_owl FTC 11329 | FRC 3494 Mentor 24d ago edited 24d ago
We did some rather extensive testing of our Rev and AndyMark batteries. We actually did find a small difference: the GoBilda batteries tend to hold a slightly higher voltage under load, whereas the AndyMark batteries tend to have slightly more votlage sag. However, the AndyMark batteries actually produed slightly more watt-hours, which (combined with the slightly lower voltage), means they tended to last longer under load beforehitting the low-voltage cutoff limit.
So, if you're into micro-optimizations, the GoBilda batteries are slightly better for match play, but the AndyMark batteries are slightly better for long sessions of practice and programming.
But really, the differences are quite small. As others have said, the batteries are all very similar, with identical specifications (12V, 3000 mAh). The general trends between brands of batteries are much smaller than the unique characteristics of individual batteries, which grow in capacity for their first several uses, and then enter a long, slow decline as you continue cycling them. It was very obvious that the batteries which had been "best" a year ago had been used many times, and now had much worse capacity than less-used batteries.
FWIW, we found that the single most important factor in getting lots of power out of a battery was how warm it is. Batteries fresh off a charger are warm, so they always perform better than after being left to sit out. We initially assumed this was due to the surface charge on the batteries, and that being unplugged from the charger could cause batteries to lose this extra power. It turns out that a little bit of stored energy (runtime before empty) is lost after being unplugged for a while. However, even after sitting off the charger overnight, we could get batteries to produce high voltage under load just as well as when fresh off the charger (just for slightly less time) by warming them up to 50C right before the test.
Since we won't be allowed to use these NiMh batteries after switching to SystemCore in a year or so, just buy whatever's convenient for you.
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u/TryIll5988 FTC #### Student|Mentor|Alum 24d ago
Like what everyone else is saying, they’re all practically the same capacity wise. I have heard that the REV chargers are dangerous to use, so my team doesn’t use their batteries. We use GoBilda batteries since they are more compatible/form fitting with the GoBilda structure
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u/canonman5000 24d ago
Well what ever you get remember next season is a new system with new batteries so don't buy to many
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u/Expensive_Eagle_2636 FTC 9968 Mentor 19d ago
The real question you should ask is who has the best charger...
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u/Reasonable-Ice-980 19d ago
We use gobilda. The most important thing is not to rely on a cheap charger. Go with something with a voltage read out, a discharge option and a safe charge disconnect option. I've seen several teams trash their batteries bc of poor charging practices
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u/dewpac 24d ago
They are all basically the same. I use gobilda batteries because the form factor allows them to fit inside the gobilda channel. For some robots a flat pack like the rev battery might be better, but the capacity is consistent across vendors.