I fried my Maker X HI100L VESC

I’ve bought Maker X HI100L VESC around 6 months ago,

today I finally assembled my DIY scooter, and went for a ride.

After about 1km, the vesc blew!

MOS temp was around 60 deg C at that time, and a white flash came out of my vesc :frowning:

I was only running about 100A motor current at that time!

VESC was placed onto additional aluminum heatsink, so thermals were normal.

I’m running 16s batteries, but the battery is brand new, and this was the first test of the e-scooter.

Battery voltage was only at 57V

I have disassembled the VESC and 2 of the 6 mosfets have exploded (burned) and 1 mosfet driver IC buenrd aswell… **But the interesting part is that one non burned mosfet has convex top surface, meaning weak heat transfer to aluminum heatsink…

Also since, the mosfet driver is burned, I suspect that the mosfet driver was firstly burned, leaving both MOSFETs turned ON, which fried them…

Do you think there could be manufacturing defect?

See the provided link: I’ve recorded a video of the mosfet that has a convex top surface!

I really did not exceed mosfet temperature of 60 deg C when the mosfet burned…

What do you guys think?


The video of the MOSFET with convex top surface can be found here:

contact maker-x for warranty




its really cooked! but first you forget the bbq sauce :laughing:

at time time of kaplow? for how long?..

Theres no way thats sustainable for a that amount of fets. (unless theres more fets on the other side?. )I dont care what maker-x claims it can do. Do you have the exact part number for those fets?

Could also be soldering issue or angry motor.

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It was not 100A continous… 100A was only for about 3 seconds, and the FET’s blew…

Part number is: IRF7759 and is rated at 160A continous or 113A at 100 degrees C.

It could be FET’s soldering issue.
The mosfet driver is fried, and it could have left both phase mosfets turued ON, which caused the explosion…



These are not the only factors you need to consider.
Also the temps your refering to are on junction to Tc (case). junction to Ambient will give you a more realistic number.

If you pull 100A with Rds= 1.8mOhm. it equals to 18W dissipation.
The Pd max at 25C ambient is 3.3W.

On page 3 of the datasheet you can also see the notes to which conditions these tests are done.

in other words, you should be able to draw 26A all day. given you can maintain the ambient of 25 Celsius. Put these badboys into a box and I promise that temp wont stay at 25 C.

These estimations isn’t the full truth either. Doing a full calculation matrix with SOA etc on a fet takes a bunch o’ time.

This introduces alot more trouble indeed. From experience I’ve never had the DRV fail (tossing errors->poof) + it then pulling a FET with it. But if a Fet blows up (due to shit soldering etc) the DRV could likely take dmg depending on what happened.

How does the DRV look? Is it also blown open or no visable dmg? If the latter, I’d say it was most likely the FETs caussing drama.


heres a AN from infenion discussing ways to squeeze out thermal performance from the FET:


One DRV is blown!

I did not get the response from Maker X yet! I hope they can atleast give me a discound on new vesc…

And I was running 100A phase amps for few seconds, Battery Amps were limited to only 40A!!


In the end it should be the vendor that has to pony up if you’re within what they consider OK limits :man_shrugging: So I think you’re in the clear.

Just trying to make a point that sometimes vendors promise too much :slight_smile:

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Thank you for your message!

Yeah, I was thinking the same thing… I was not even pushing the vesc to the limits!

Maker X staff is really unresponsive, which is getting depressing :frowning:

I was forced to buy new VESC HI200, so I can ride my scooter asap, but there is still no answer about my fried HI100L…

Really dissapointing overall :frowning: