Noobish ESC load question...
 

So my great idea was to run my mostly aluminum/Ti 3905 w/ 1515 1Y and a Quark 125B on 5 cells for me and 3 cells to slow it down for my son. Stock spur and 21pinion, stock diffs (not for long) and 40 series mulchers.

Well it thermals after about 5 min on 3 cells (MaxAmps 5000x2 in Parallel)- the only batteries I have tried with the quark.

So does the ESC work harder (pull more amps) when trying to run a big motor on lower volts? i.e. it will run hotter on 3S than 5S under the same conditions? Or is the Quark just that temperamental (I have since put the Monster heat sink and 2 fans on it - but haven't run it)?

I ran 5S (2S+3S MaxAmps in series)on my new Mamba Monster I put in it and the fan only kicked on a couple times during a 20 minute bash. Didn't try 3S yet.

It is probably obvious what is happening, but I couldn't find the info searching... thanks for any help... I doubt a lot of people on this forum have even thought of running 3S in their trucks/buggies...

Just increasing the voltage WILL increase current draw and heat. But, you generally gear down for the same speed. This will make everything run much better.

I think he was trying to say that it got hotter on 3S than it did on 5S - is that correct?

Shouldnt do.

If you just bump up the voltage from 3s to 5s without changing the gearing, the esc will run hotter like Brian said. If you set the gearing for 5s, then went down to 3s without re-adjusting it, the esc should run cooler due to a much reduced load.

Did you gear the car to be what you want at 5S? Then at 3S it will be about 60% the speed - but potentially still pretty fast as that put that motor (which is pretty high kv) around ~25k rpm.

Only thing I could think is that with high gearing trying it with 3S (if it was gearing for say 35+ on 3S) and with all the AL/Ti you have on it - it may be very heavy and a really strong load to push with 3S and Amps may have been through the roof.

I've never had a Quark personally, but seems almost everyone has had heat issues without modding it with more heat sinks.

Also - never really read much about how hard the Neu motors are on a Quark or if they even run that well.

I say if you are running comfortable temps on the MMM with 5S you should be good to go. Like the guys said - gear it for 5S and then 3S should be much easier on everything.