Lipo problem or overheating issue?
 

I am having a problem with my electronics. I set my Lipo cutoff on my esc at 3.4v per cell but when I check my voltage after a run it reads 3.7-3.8v per cell. I run the vehicle till I notice a power drop and about the same time it shuts down. The electronics are hot to the touch after a run and my run lasts approximately 20 min. My battery is a Dynamite Silver 3000mah 7.4v 20c Lipo and my esc is a Dynamite 45A. The motor is a Dynamite Tazer 3300kv with the stock 25/86 gearing. The truck is a Losi XXX-SCT. Sorry if I am overloading, just trying to convey as much information as possible.

I would try dropping a few teeth on the pinion gear and see if that helps keep your setup cool. You will lose some top end speed but will see more low end torque. As far as the cut off on the speed control I dont know what would cause that. Is your battery getting when your done running?

The load of the RC will pull the battery voltage down. After you stop the voltage will rebound up some to what is frequently called the resting voltage. The cutoff is working fine.

It would be helpful to know the actual temperature after the run to determine gearing. Perhaps invest in a relatively inexpensive temperature gauge.

So what your saying is that the voltage may drop to the cutoff while driving but when it is stopped the voltage will come back up correct?

Exactly. Battery voltage always drops under load.

And warm electronics is not unusual after 20 minutes. Need temps to really know if it is too warm.

Yes..also set your LVC to 3.2 volts per cell.

Any yes drop your pinion a few teeth...like closer to 20.

:nod::nod::nod:
As was stated, a temp gun is a must in rc racing, if u wanna keep the elecs lasting longer:)

No need to run after you notice a power drop off. Just unnecessary wear on the lipo for very little run time gain.

Thanks for all the help and info guys. I'm an old school guy getting used to new technology. What is a reasonable temp for brushless electronics?

You should bump up your lipo C rating...30C minimum, preferably 40C and above.
Max temps: Battery-140* to 150*
ESC- 185*
Motor- 170*

140 to 150ºF seems high for a lipo, I thought they went into thermal runaway around 140º? A lipo in a 2wd shouldn’t be warming up much, maybe 5 to 10º, if it is then yes a higher C lipo would be wise. If it’s not getting warm then it’s fine. I suspect a 20C lipo in good condition would be OK for the motor and ESC mentioned, early lipos were less than that and they worked without issue, but again go by temps.

For a 2wd running long runs I’d suggest staying in the 130-140º range tops for the ESC and motor (edit). Leave a little safety margin and help reliability-long life, shouldn’t be too hard to be in that range or lower with good power.

:nod::nod::nod:
I agree:)

Thanks a lot guys. My battery stays fairly cool but I do plan on getting a higher c rated battery. Thanks again for the info.

No problem, always glad to put in my $0.02:)

I would leave your LVC on your ESC @ 3.4v you can go to 3.2v but 3.4v is best. That's what MaxAmps suggest on there Lipo care page on there site. As far as it getting hot as stated above it depends on how hot its getting and u can buy a temp gauge cheap. 86 spur should be fine with a 17.5 but 25 pinion is too high to run it that long would be different if you were running 5-6 min heats or 7-8 min mains.