no mid-range throttle
 

i'm having this nagging problem. once my equipment gets hot i lose all the midrange throttle. i'm running a bk 12020/lmt 1950/8 combo on 6s lipo. its really hard to race without my midrange. i put a fan on the esc and it only gets to about 125f-130f. could a 140f motor have anything to do with it? please help!

I jsut has the same prob with my 12020, switched motors, and still the same prob. It's the esc. What do your capacitors look like?

my caps look fine, they aren't bulging or anything. it works really well when everything is cool, but when it all heats up racing on a track becomes difficult without midrange throttle! what esc works the best for you? i see that you have a nice collection now, lol!

What is the continuous and pulse ratings of your lipo? How hot are your batts when the ESC gets that hot. With that much voltage, the current could be quite high. I've seen a pattern here from various problems where a hot ESC could mean it is starving for battery current.

i'm using polyquest "twenty" series 3700 mah 3s packs. they are rated at 74 amps continuous, couldn't find the burst rating. last time i checked the temp of the batteries it was at about 100f. i use the strobe setup with 13t, 15t, and 18 tooth in a g2r with gmaxx single speed tranny. hope this will help.

When mine got warm it also did the same thing, but for me i think it was a motor issue. For you though, it may a temp issue. My 12020 ran great until it got warm, then no mid range at all, just slow and fast! I put my 9920 back in a whalla!

could i use a 9920 with my setup? i know the maximum number of cells is the same, but what about amps?

You should be ok with a 9920.

squee, i know you like the quark, but 6s lipo? i thought it was only rated for around 5s lipo. just weighing my options!

Its rated for 6S LiPo or 18 cells NiMh.

got it. i was looking through the controllers in the store and saw the specs. what about the mgm 160amp/24cell controller, worth it?

Its nice, but I think its overkill unless your gonna run more than 6S LiPo.

Yeah, but talk about INSURANCE!!!!

i want to buy the quark, but i don't want to have to send another controller back (12020). i'm not sure what coolhand meant about running 6s successfully, but still having problems. i'm just worried about running the max voltage.

i pm'd ChC and he said the problem with 6s is only with the 80a quark. i just ordered a 125b from mike, so we'll see if it handles the voltage! thanks for the help guys!

For what its worth, the 80B and 125B are probably essentially the same ESC and use the same FETs (which means they have the same working voltage) except the 125B uses more of them to handle the extra current, hence the longer packaging. Unfortunately, the FETs don't come off the heatsink easily (I know, I tried) to verify this. As long as you use the ESC properly and stay within it's rated voltage and current, Quark has to honor their warranty. If they say the 80 will handle 6s, then it should.

just like my 12020 should work properly, lol! i understand that it "should" work on 6s, but ChC has tried that with two different 80b units with some success. the first one fried and the new one stutters or something on takeoff. i just don't want to have to buy another speed controller for my truck, that would total 3! i will use your advice from other posts regarding heatsinks, and i have 4 5v fans at my disposal. i'm sure i'll be impressed!

another question for BrianG, when i send my 12020 back do you think bk will put new power wires on it if i request, 2 instead of 4. i'm sure i'll have to pay.

Um, RCM Mike or one of the mods may be able to answer that better. I don't see why not since they have it apart anyway...

The point I was trying to make earlier is that you shouldn't have had to buy three controllers. When the first one went bad running within specified parameters, it should have been covered under a warranty. These ESCs are expensive to buy one after the other!

for sure! i dont know if my 12020 will be covered or not. it should be, since i didn't exceed any of the controllers limitations. we'll see. i've heard good things about bk's customer service. thanks.

Only thing about BK's customer service is that lately its taken a long time. Mike might be able to fix your ESC though. And I'm sure he would be able to put one 12g wire instead.

nice! i'll send him an email.