Pop! Goes The Ezrun!

[ciadelta16 0]

As you can tell from the title, I had a bit of a mishap at the weekend.

Previous weekend I had been using the car around a carpark. it is a TA04 with Ezrun 60a ESC and 5.5t motor running 7.4v 2s lipo 3200MAH. The car is geared 112/49 I believe. I had it set as this for speed runs and nothing else really. I had set the thermal cutoff on the ESC to protect the motor and this has cut in a couple of times, especially on hot days. I have always checked the ESC temp at five minute stages to check it isnt getting too hot and I have always been able to hold my fingers on it so it hasnt ever got that hot.

Anyhow, back to the story. Last weekend I ran the car in a local car park and the thermal shotdown cut in for the motor and so I turned the car off and checked the ESC, temp ok and then the motor. The motor was red hot, almost as if the thermal shutoff had failed. I left the car to cool down and havent used it till this weekend. I went out with it and within two seconds of switching it on, there was a shortage of power and lots of stuttering. Then the car went up in blaze of glory with smoke and fire and a new LIPO battery inside.

First off, I chucked the car into the road and left it to burn as I decided it would be dangerous to approach it. But after about five seconds the fire subsided enough that I could get a look into the car and see that it was the ESC alight. I quickly removed the body pins and blew the fire out and then removed the lipo. It had scorch marks on the hard outer shell but luckily looks ok. Body and chassis are ok too with only a little smoke damage. The ESC is gone and I think that the fire subsided due to the solder melting and the battery connections coming away from the ESC itself!!

Could have been a lot worse but I want to learn from this mistake and find out exactly what I did wrong that caused this to happen. The sooner I learn from this then the sooner I can modify my TA04 to stop this happening again.

[WillyChang 1814]

always been advised sensorless BL motors don't have temp sensor/s in the motor, only sensored do (part of the 6-wire sensor lead)

so the ESC would only be monitoring its own temperature, wouldn't know what the motor is up to

when motors get too hot they'll unsolder something and cause an internal short which the ESC has no way of escaping

[Butler 338]

Wheres the pics!!!

[ciadelta16 0]

Wheres the pics!!!

Been too scared to look at it anymore:)

I will sort some out later and post them .

[ciadelta16 0]

always been advised sensorless BL motors don't have temp sensor/s in the motor, only sensored do (part of the 6-wire sensor lead)

so the ESC would only be monitoring its own temperature, wouldn't know what the motor is up to

when motors get too hot they'll unsolder something and cause an internal short which the ESC has no way of escaping

Correctomondo Willy. I just read the manual again and the overheat protection is for the ESC only. SO . . . .Motor has cooked which caused it to cook last week and this week, I connect the battery, the motor has shorted and it cooks the ESC. Job Done!!

Lesson Learned the hard but cheaper Ezrun way. Can I ask if the Lipo would still be ok to use if the motor has shorted and taken the ESC with it??

Cheers.

Luke.

[WillyChang 1814]

usually yes... check each cell's voltage, if between 3.0-4.2V/cell then it should be ok

if its motor shorting out it'll spike thru the FETs which either blow up &/or unsolder themselves from the PCB

so odds are the battery wouldn't have suffered a long period of current draw in excess of its rating (20/25/30C etc)

be safe & recharge it supervised anyways

in some ESC fires the battery input leads get unsoldered then short each other out... that's when all bets are off

[ciadelta16 0]

http://www.tamiyaclub.com/showroom_model.asp?cid=100743

Here are pics for those that want to laugh at my misfortune:)

[Blacque Jacque 4]

Mmmmm, toasty.

On the basis that the motor was the first thing to get hot, I'd say it's most likely failed (probably overheated the insulation on the windings leading to a major internal short). Once that had gone short, it took out the ESC before it could trigger the thermal cutout.

[OldFrogga 0]

Ouch! it would be a good idea to get a temp gun so you can accurately check the motor temp, you can buy them off ebay for like $10-20, i wonder if you didn't have the car geared well enough to suit the motor.