KB-45 Heat
 

Hey guys,

I'm pretty new to all this electric stuff after converting my Monster GT to a brushless truck, and I've learned to make sure the stuff I put into the truck is up to challenge of moving it.

So far I've burnt up a Turnigy 100a Plush ESC, and a KB-45 8L 2300kv motor... That's way over $100 up in smoke.


So I now have an MMM in the truck, with the V3 case on the way and the new 1.20 software installed. But I've noticed that my new KB-45 8XL (XL not an L this time) seems to get warm even without a load. When I spool the motor up without the pinion gear on it, after about 15-20sec of just seeing how fast it's gonna go compared to the 2300kv motor, it touch it and it seems warm. Maybe 100-110ºF (not that warm I know, but with no load I expected 0 heat). Is this normal? I'm afraid that with the 14lb truck the motor will overheat like the last one and will demagnetize. The gearing will be 14/58 if anyone cares, don't know the gear ratios of the tranny and diffs...

Thanks in advance

BL motors do heat up with no load on them, it's actually not good to run them without a load as they can over rev and shatter the magnet. A Monster GT is a big heavy truck and IMO that motor will most likely not be up to the challenge. When this motor dies you may want to consider a Neu 1515 or bigger or a 70-80mm Medusa with a kv value near 1600-1700. For your wallet's sake I hope your new motor hold up, good luck!

Brushless motors shouldn't be run too much without a load. They do heat up quickly this way. It seems strange, but they run more efficiently when there is a proper load on them. I've read several recommendations from company reps that say not to run without a load other than to briefly test/check rotation.


edit: oops, you were too quick for me e-revonut

The KB45 will be up to the task. I've got a spare KB45 10XL and some 6mm scetyl pinions if you're interested. :wink:

really?

The kb45 is bigger than the neu 1515.

are you sure you didnt mix this motor up with something else?

these motors are beastly.

kb45 will push it no problem. on 5s you'll be fine, I'm going to run mine on 6s in an e-maxx

that's nothing dude, tip of the iceberg.

I run the kb45 8l in my gtp and it is geared for 50mph. No issues at all with that load. With the 8xl you will have plenty of power. It will run warm, but I do not see you having any issues with it. No load revving a motor is a bad idea. Even a little throttle can push an unloaded motor past its max rpm. All bl motors will heat up fast if run unloaded.

Alright. Hopefully the 15sec I ran it for, actually, maybe around 5-7, didn't do too much harm. I like to exagurate I guess...

And just for everyone's info:

KB-45 8XL
1600kv (some say1700kv)
45x77mm
6mm shaft
It's a beast!

I have the pinions down, but thanks for the offer above. If this motor dies, the 10XL may be the next step, or a Medusa. I'm scared, but somewhat confident.

Thanks guys! Tons of replies in just a hour or so!

No prob, but pics are required. If you do not post them, BrianG will most likely flood your PM box with pics of himself in ladies undergarments. Watch out for him...very strange.

Tomorrow I get a new pinion gear to bore out for the new motor (last pinion's set screw stripped, couldn't get it out...) so I'll take updated pics then. All the pics I have now are of a truck with a smaller motor and way weaker ESC.

kershawdesigns.com sells 6mm bore pinions.

Sorry wasn't sure, I was thinking this was the even cheaper version of a Feigao.:whistle:

Very different. KB45s aren't "spinning toasters of death" -SuicideNeil

I've seen them, but unfortunately, they only sell like 19-20t pinions. I need a 14-15t. So I've been boring out RRP Extra Hard 5mm Pinions. Last one worked great! Until I used my old tools to try and take out the set screw... I need a new 2mm hexdriver, just a few bucks I guess.