PDA

View Full Version : Can Revolt use 5000mAh 4s 20c lipo?



jetskier
04-13-2013, 09:24 AM
Can a stock Revolt 30 use a 20c lipo with 4s and 5000mAh capacity? I'm new to lipo and I got a Grimrace expensive battery and a cheap HK 5.0 4s 20c to try it out performance/price comparison. Its going to be sports running only. What is the formula for 20c and what do I need to watch for?
Thanks for the expertise.

chipgibbs
04-13-2013, 10:07 AM
20C is a little low and 5000mah is a heavy battery for the revolt. I use 4200mah 35c in my all stock Revolt.

30C is the minimum recommended by Aquacraft.

CG3

siberianhusky
04-13-2013, 10:33 AM
No problems at all with the 5000mah but the 20c part is cutting it close. Your boat shouldn't pull 100amps if it is running well. The batteries will probably get a bit warm and may not last as long the caps on your esc will get hot - probably.
I KNOW the esc will not live for long if run cont. at 100 amps, spikes are ok, I see those around 100 all the time. Your average amp draw is probably about the 50's if it's stock. the esc is rated at 60.
Being said I wouldn't do it, a battery that is at it's limit in current supply can damage more than just the battery. Ripple current would more than likely take out the esc before the batteries went over the hill.
When dealing with HK batteries it's also best to take the C rating with a grain of salt, there is no standardized test for C rating. I do have some HK packs and would recommend going double what you think you will need in C rating with them. Not a huge difference in price and better to be safe than sorry.
Multiply the capacity by the C ratting and you will have the amps the pack can supply. so 5 A/h x 20c = 100amps.
Same for the "burst rating" but this is the maximum the pack can supply for a very short time.

jetskier
04-13-2013, 10:54 AM
Thanks for the reply. Question.. The stock ESC is rated @60A does that mean it can handle 60A max or it can supply 60A max?

BHChieftain
04-13-2013, 11:52 AM
You can get away with those packs if you prop down, but you really want 35C 5000mah packs.

The Amps on the ESC are the load it can handle. The boat motor will PULL amps depending on the load (determined by the prop) to try to keep the RPMs constant (determined by motor KV and battery voltage). The ESC blows up when you put too much prop and spike the amps. If the batteries can't handle the requested Amp pull requested by the Motor (ie, due to too low C rating), then the batteries overheat, puff up, and other bad things happen.

Chief

jetskier
04-13-2013, 12:05 PM
that explains it very clearly now. thanks again.

jetskier
04-14-2013, 12:44 PM
I contact HK and they were able to do a swap. I got the Zippy 4500mAh 4S1P 45C a try.

D for Dummy
04-17-2013, 05:09 PM
I just picked up 2 pairs of 2s 4500mAh 65c. I've slightly puffed three sets of GrimRacer 2c 5000 40c. :(