Troubleshooting Burnt Controller after Battery Upgrade

[anerickso123]

Ive been attempting to upgrade the battery and motor on this 36v ATV. Everything was working at first. Then it failed to turn on. I opened up the controller View attachment IMG_0696.jpegView attachment IMG_0629.jpegand found it had a burnt plastic smell inside. Hoping it get some guidance on what to do differently to prevent this same result.

This is what I did: I cut the wires on the controller and connected it to the t-plug adapter that came with the battery using wago connectors. I then plugged in a new motor along with the throttle into the controller and everything was working. The throttle was turning the motor. I then worked to remove the old motor and during the process I may have damaged the wires on the throttle that connect to the controller. Once I got the new motor installed, I reconnected everything and nothing was turning on. It seemed to me that the controller was dead, and that does seem to be the case based on the smell.

I’m gonna buy the same controller as it’s the only one I can find with reverse, three speed controller, and 36v 800w. But what should I do differently? I’m thinking of using XT60 adapters instead and trying to crimp the wires together instead of using wago. I’m also curious if the damaged throttle could have been the culprit not so much the battery connection itself. Any advice would be very much appreciated as I’m close to throwing in the towel on this upgrade. Thanks.

 

[E-HP]

I’m gonna buy the same controller as it’s the only one I can find with reverse, three speed controller, and 36v 800w. But what should I do differently? I’m thinking of using XT60 adapters instead and trying to crimp the wires together instead of using wago. I’m also curious if the damaged throttle could have been the culprit not so much the battery connection itself. Any advice would be very much appreciated as I’m close to throwing in the towel on this upgrade. Thanks.

Whatever you can do to improve air circulation around your controller should help.

 

[neptronix]

If there's a burnt plastic smell inside the controller, then some components are damaged inside. Any pics of the carnage?

Did the vehicle originally have lead acid batteries?

 

[anerickso123]

If there's a burnt plastic smell inside the controller, then some components are damaged inside. Any pics of the carnage?

Did the vehicle originally have lead acid batteries?

I didn’t see any visible damage, just the smell. Yes originally the vehicle had lead acid. This is a new controller, but it does seem it’s more designed for lead acid based on the fact that the wires are 14 awg and the lithium battery is 12 awg.

 

[neptronix]

Eh, i wouldn't base 'designed for lead acid' around the wire gauge, usually manufacturers try to skimp there whenever possible.
I would say it might be a lead acid controller because it's brushed and that's very old tech, usually found in use with lead acid batteries.

It could be that it couldn't handle the large inrush of energy from the lithium if it was designed for lead acid.
The more powerful the lithium battery, the bigger the controller caps, the larger the spark.. so it's typically a good idea to run antispark connectors. In this case, the spark is going to be small, but maybe the controller couldn't handle it.

Thought about doing an autopsy on the controller to see what popped inside?

 

[anerickso123]

Eh, i wouldn't base 'designed for lead acid' around the wire gauge, usually manufacturers try to skimp there whenever possible.
I would say it might be a lead acid controller because it's brushed and that's very old tech, usually found in use with lead acid batteries.

It could be that it couldn't handle the large inrush of energy from the lithium if it was designed for lead acid.
The more powerful the lithium battery, the bigger the controller caps, the larger the spark.. so it's typically a good idea to run antispark connectors. In this case, the spark is going to be small, but maybe the controller couldn't handle it.

Thought about doing an autopsy on the controller to see what popped inside?

Okay thank you, that does sound plausible. What do you recommend for anti-spark connectors? I’m looking at XT90-S online, I could try to convert everything to that. The original acid battery also had a fuse within the red wire, would the XT90-S be sufficient, or is it worth trying to get a fuse within the red wire near the battery?

Here are some pictures, it does look pretty immaculate to me, I’m still gonna try a few things before I give up on it and assume it’s dead:

 

[neptronix]

xt90's are fantastic, i run them on everything.

hmm, if you don't see anything looking burned, then i'm puzzled. Normally one of the IC's, capacitors, or mosfet goes boom when a controller goes. Maybe the controller isn't dead.

 

[E-HP]

xt90's are fantastic, i run them on everything.

hmm, if you don't see anything looking burned, then i'm puzzled. Normally one of the IC's, capacitors, or mosfet goes boom when a controller goes. Maybe the controller isn't dead.

Maybe the relays got fried.

 

[fill]

If switchless (on/off) the battery can on initial connection pop/bang, even spark, the reason being (as i have read..) the initial inrush of current required to provide the on board capacitors with their initial charge combined with a shaky physical connection that can result in the sometimes loud Pops or bangs.

one of my batteries is switchless even in the hailong format and it scared the life out of me when i initially slid it onto my bikes battery cradle.

The XT90 connectors mentioned above also come in an anti-spark variety for a $ or 2 more, or google for a diy circuit you can wire in yourself if so inclined.

Also be mindful that your battery pack should be able to provide ample overhead amp capacity compared to what can be drawn safely. your controller can draw upto 30a, if your battery/bms isnt rated to supply sufficient power (amps not to be confused with amp hours) you risk possibly damaging the cells at worst or suffering power cut outs at speed/under load at best. And while your pack may well be suffuicient its not apparent from the pics posted..