Tetrix Battery Holder vs. NiMH

[noa_n_f]

What is everyone's view on the battery for their minibot? The NiMH is quite expensive and it would be dangerous to only have one, in the event that it runs out of battery during competition.

Is there any major drawback if one were to use the tetrix battery holder instead? i.e. weight, power output, size, etc.

Just a thought...

[Chris is me]

You are only allowed the provided battery for the minibot.

[Techhexium]

Yeah, the battery holder is illegal in FTC too. You really want to charge it as much as you can before and between matches. If you charge in 1.8 amps, the NiMH will take 20-30 minutes to charge back to full capacity. If your budget allows, buy a second battery or borrow one.

[Al Skierkiewicz]

Noa,
There are other threads on the FTC battery that might make you feel better about charging. Just search. It is always a good idea to have a spare, battery motor or fuse.

Originally Posted by Techhexium

If you charge in 1.8 volts, the NiMH will take 20-30 minutes to charge back to full capacity.

Do you mean 1.8 amps?

[wilsonmw04]

I will stay, from my FTC experience, that the battery is quite a good one. We are able to run one FTC bot with 4 DC motors and 5 servos for ~20 minutes before recharging without any noticeable reduction in performance. We always worried about our NXT batteries more than our primary battery.

Of course for those trying to be on the razor's edge of speed, you won't settle for anything other than a fully charged battery.

[noa_n_f]

Okay, thanks everyone. This information helps a lot.

[Techhexium]

Originally Posted by Al Skierkiewicz

Do you mean 1.8 amps?

Yes it is amps, I mistakenly put in volts.

[PhilBot]

As a veteran FTCer, I recommend that you only charge the batteries at the lower 0.9A setting.

In our first year we used the higher setting and had a lot of trouble with overheating. The batteries got so hot they melted the shrink wrap.

These batteries have good capacity, running at least 4 motors at high load for over 2 minutes in FTC. 20 seconds every 10 minutes won't need the high charge rate.

However having a spare battery in case yours fails would be prudent.

Originally Posted by Techhexium

Yes it is amps, I mistakenly put in volts.

[Techhexium]

Well, I only been in FTC for two years, and my team charges the two batteries we have at the higher rate and we never had any melting problems before, and the batteries have been used for two seasons. Maybe we're just lucky, but I'll start charging them at 0.9A because it's off-season for every team in CA and it helps preserves the battery's life.

However, a couple months ago the batteries' fuses blown, but we replaced the fuses and fixed our wiring and they still work.

[PhilBot]

I went back to my notes and found that the problem with the batteries wasn't melting, but leaking on the higher charge rate (they did get pretty hot).

The red insulating paper at the end of some batteries were darkenning up due to internal leakage. I reported this and they were replaced, with the recomendation to use the lower charging rate.

The original battery packs had clear heat-shrink, so you could see this problem.

The newer ones now have black heat-shrink....
Unfortunately this masks any potential problem indicator

Phil.

Originally Posted by Techhexium

Well, I only been in FTC for two years, and my team charges the two batteries we have at the higher rate and we never had any melting problems before, and the batteries have been used for two seasons. Maybe we're just lucky, but I'll start charging them at 0.9A because it's off-season for every team in CA and it helps preserves the battery's life.

However, a couple months ago the batteries' fuses blown, but we replaced the fuses and fixed our wiring and they still work.

[wilsonmw04]

Originally Posted by PhilBot

I went back to my notes and found that the problem with the batteries wasn't melting, but leaking on the higher charge rate (they did get pretty hot).

The red insulating paper at the end of some batteries were darkenning up due to internal leakage. I reported this and they were replaced, with the recomendation to use the lower charging rate.

The original battery packs had clear heat-shrink, so you could see this problem.

The newer ones now have black heat-shrink....
Unfortunately this masks any potential problem indicator

Phil.

I can second the problem with the older batteries. We had the same problem with leakage. The new batteries are harder to tell if this has been fixed. I'm not sure which was shipped from FIRST choice.

[Techhexium]

The batteries with warning labels and black heatshrinks are shipped from FIRST choice, I seen then in the FIRST Choice PDF. These are the same batteries that have started shipping in fall 2010 for FTC.