# Smelled something burning.



## Ziggythewiz (May 16, 2010)

It is getting hotter out, so with much highway driving it's no surprise if things are getting warm. Did you try feeling anything to see? To begin with, try feeling cables, motor, and controller just after a typical drive, then try it again after short highway run for comparison. I'd recommend getting a thermal gun and start planning how you can add some heat sinking and/or forced air cooling.


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## mizlplix (May 1, 2011)

Wiring usually smells like rubber or plastic when over heated. That "Trash" smell just might be the papers and insulating varnish in the motor.

Hard to get an accurate temp on it externally.

Do you have a forced air blower, or is it normally cooled?

Miz


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## gojo (Feb 1, 2011)

Ziggythewiz said:


> It is getting hotter out, so with much highway driving it's no surprise if things are getting warm. Did you try feeling anything to see? To begin with, try feeling cables, motor, and controller just after a typical drive, then try it again after short highway run for comparison. I'd recommend getting a thermal gun and start planning how you can add some heat sinking and/or forced air cooling.


I found a loose battery connection, and I suspect that may have been the problem, however it has made me more concerned about the motor. I have an IR gun, and I am going to monitor the motor temp. I was monitoring the motor when I was watching the controller, and checking my wheels, but I haven't been checking the motor lately.


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## gojo (Feb 1, 2011)

mizlplix said:


> Wiring usually smells like rubber or plastic when over heated. That "Trash" smell just might be the papers and insulating varnish in the motor.
> 
> Hard to get an accurate temp on it externally.
> 
> ...


I found a loose battery connection; along with melted lead, and suspect that was what I smelled. I emailed Netgain, and got a prompt answer from them. If it was the motor they thought little damage would have been done, but I should avoid over heating it in the future. They mentioned the motor likely has a snap switch to protect it at some point.

I don't normally do much highway driving, however George at Netgain told me stop and go is the hardest on over heating the motor. He said keeping it at higher RPM's will keep it running cooler.

I have no special cooling for the motor. I plan on monitoring it with a thermal gun, but like you said, I don't know where to get an accurate reading. The motor casing was hot, but I could put my hand on it for a second or two without getting a burn.


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## Ziggythewiz (May 16, 2010)

If you melted lead, I'm sure there's little need to look further. It is good to be aware of nominal temps though, so you can troubleshoot when you do think something is off.

It's best to remove the debris cover and shoot the brushes. Just move it around some and record the highest number you see. I did some experiments with mine last summer to see what my peaks were when running in 2nd, 3rd, and 4th gear. I found the blower I added did nothing for me in 2nd, but helped significantly in the other gears where the self cooling is more limited and the temps would normally get higher.


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## dragonsgate (May 19, 2012)

If it got hot enough to melt the lead then keep an eye on the seal between the post and case. It might start leaking electrolyte when gassing or any time it feels like it. This can cause extra corrosion problems and a mess. No amount of silicone will stop it.


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## ruckus (Apr 15, 2009)

gojo said:


> I could put my hand on it for a second or two without getting a burn.


That is not "hot". That is "warm". The thermal switch on an ADC is set to 250F, but the motor is supposed to tolerate quite a bit more. I have a motor that is running this temp on long highway drives. The Helwig split redtop brushes are reported to reduce temps by 20% (see the last 2 EVTV episodes). I will be testing this, as well as mounting a blower. It is like a new woodstove. Smells like hell, but is just getting broke in.

Obviously though, lower temp is better.


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## gojo (Feb 1, 2011)

dragonsgate said:


> If it got hot enough to melt the lead then keep an eye on the seal between the post and case. It might start leaking electrolyte when gassing or any time it feels like it. This can cause extra corrosion problems and a mess. No amount of silicone will stop it.


Sounds like you've had some experience. The arc took down a corner, but I was able to level it again with a dremel. I didn't see any leaks at the time, but I'll look again.


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## mizlplix (May 1, 2011)

> The Helwig split redtop brushes are reported to reduce temps by 20%


I hope they are referring to "brush" temps.

I fail to see how any super-duper brush will decrease motor temps by any meaningful amount. Current is current, load is load. 

Kinda like reducing brake rotor temps by drilling holes. Sure it decreases temps (a small relative amount), but it now increases pad wear, starts stress riser cracking and reduces attendant braking ability by reducing the effective rotor/pad friction area. (It has all been proven)

Miz


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## dragonsgate (May 19, 2012)

Ha ha sounds like we have two separate conversations going. One about motor temp and one about battery posts and now possibly another about break rotors. I am referring to hot lead and it is not a cowboy western. If you could clean up your post with a file it is possible the arcing did not transmit enough heat down the pole to affect the seal. Keep an eye on it anyway. I have had a couple of experiences with melted and broken terminals. One was a broken terminal on a marine battery in a boat I owned. It was a new battery and I was installing it. There might be a lesson in there about getting over zealous when it comes to tightening battery terminals. Being in my early 20’s and an impetuous youth I decided to fix it rather than take it back and try to exchange it. I gave no thought to the amount of heat I had to apply and its effect on surrounding parts. I got it melted back together and it looked good from all outward appearances but it almost immediately started seeping electrolyte around the post. Nothing I tried would keep it dry. The second experience was a little more dramatic. It was my fault… (Again). I had been cleaning the battery tops and checking for corrosion. I had taken a couple of the terminals loose I guess I failed to sufficiently tighten the nut on the last positive post in the line going to the controller and motor. Thinking I had done a good job I jumped in my electric for a quick trip to the hardware store. It was a nice day and I was felling good so on the way home some of that lingering impetuousness surfaced. I had pulled out onto the highway from the store and was doing almost thirty mph when I slipped it into third and mashed the accelerator. The Speedo was climbing to 60 when I heard a PFFFT! I looked in the rearview mirror and saw thick gray smoke coming out from under the mid-engine cover. I immediately shut everything down and coasted to the side of the road. My controller is only 500 amps and I was pushing just about every one of those amps through that terminal when it melted and the lead flew. The positive post was gone and hot lead had splattered over and melted through the tops of the last two batteries in line. After the disbelief subsided I evaluated the situation and reconnected the cable to the third battery from the end and eased it home. The pack was over three years old so I went to my battery outfitter and got two used T875’s to replace the shot ones and ran for close to another six months before I got new pack. I only pay attention to car races when something blows up or a really cool wreck happens. I have often wished that I could have seen my incident from another angle. I bet it looked fairly impressive going down the road with all that smoke billowing out of the middle of the car.


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## ruckus (Apr 15, 2009)

mizlplix said:


> I hope they are referring to "brush" temps.
> 
> I fail to see how any super-duper brush will decrease motor temps by any meaningful amount. Current is current, load is load.
> 
> ...


In the last 2 episodes of EVTV they document the 20% temperature drop.


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## DavidDymaxion (Dec 1, 2008)

I had my motor about that hot once, and the motor was emitting wisps of smoke! It did continue to run fine after that, thankfully I caught it early.

Another reason to keep the motor revved up: You don't want to be steadily in current multiplication mode, as heat ~ current squared (2x the motor current 4x the heat).


gojo said:


> ... The motor casing was hot, but I could put my hand on it for a second or two without getting a burn.


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## gojo (Feb 1, 2011)

DavidDymaxion said:


> I had my motor about that hot once, and the motor was emitting wisps of smoke! It did continue to run fine after that, thankfully I caught it early.
> 
> Another reason to keep the motor revved up: You don't want to be steadily in current multiplication mode, as heat ~ current squared (2x the motor current 4x the heat).


I don't have a tach because I don't have room for a tail axle, so I figured out a poor man's tach and put a copy on my dash. My range in each gear is 2000 to 3500 RPM's. I red line at double my 2500 speeds. 

@2500 
1st 12 MPH
2nd 20 MPH
3rd 31 MPH
4th 44 MPH
5th 53 MPH

2nd 16 MPH to 28 MPH 
3rd 25 MPH to 43 MPH
4th 35 MPH to 61 MPH


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## dougingraham (Jul 26, 2011)

ruckus said:


> In the last 2 episodes of EVTV they document the 20% temperature drop.


That is an unloaded motor. The only energy being used is going to waste heat. It is easy to see huge changes in this situation. He was seeing around 500 watts going into the unloaded motor. If you are running down the highway this is not significant from a heating standpoint. You might be pulling 40000 watts (approx 50 HP) to go down the highway at 65mph and that tiny change will not be noticed in the motor heat. at 40000 watts and 90% efficiency (lets be generous) this is 4000 watts of waste heat. With the good brushes it might be 50 watts less and with the bad brushes 50 watts more waste heat. As far as motor heat goes in operation insignificant.


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## ruckus (Apr 15, 2009)

Well, mr. "conversion in progress" I can tell you that armchair theory and real life are quite a bit different. Of course I see how loaded and unloaded are unique situations. What you are not wanting to hear is that forklift brushes suck when used in an EV application. Not only is there massive amounts of extra heat generated, but the brushes CANNOT withstand significant current either. It is a case of absolute and total FAIL.

I will test the brush upgrade and report actual temperatures and facts, not empty speculation based on lack of experience.

Cheers


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## dougingraham (Jul 26, 2011)

ruckus said:


> Well, mr. "conversion in progress" I can tell you that armchair theory and real life are quite a bit different. Of course I see how loaded and unloaded are unique situations. What you are not wanting to hear is that forklift brushes suck when used in an EV application. Not only is there massive amounts of extra heat generated, but the brushes CANNOT withstand significant current either. It is a case of absolute and total FAIL.
> 
> I will test the brush upgrade and report actual temperatures and facts, not empty speculation based on lack of experience.
> 
> Cheers


Unloaded there is little difference. Loaded the i^2*R losses cause the difference to be greatly amplified. In looking at the test data it is clear that the old brushes in Jacks test motor had both higher resistance and greater drag on the comm. I have a lot of experience with brushed DC motors, just not in cars (yet).

I have no idea why you would think I wouldn't want to hear that forklift brushes perform poorly in EV's. They are probably a harder compound intended to operate at a couple of hundred amps tops for short periods. I wouldn't expect them to perform well in an EV environment.

I have already changed my brushes from the H49 to the H60 compound. The H60 takes a lot longer to seat. I have about 15 hours of run time so far and they are a lot quieter than when I started but they still make more noise than the H49 compound brushes did after just an hour or two of run in.


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