BAC8000 mosfet and capcitor replacement

rivvs

100 W
Joined
Nov 17, 2019
Messages
148
Location
Quebec
Hi, so I have a BAC8000 controller that survived a battery fire but the hall sensor do not work anymore so I opened the controller to see if it was repairable. Looking at it the control section of the controller seems to be too small to work on it. Then I got the idea that it could be possible to replace the mosfet and the capcitor so that it could work with 96v nominal. I have attached picture of the controller. The bac8000 use alpha&omega t290 mosfet.20210425_134958.jpgIMG_1680.JPEGIMG_1681.JPEGIMG_1682.JPEG
 
rivvs said:
Hi, so I have a BAC8000 controller that survived a battery fire but the hall sensor do not work anymore
What "hall sensor"? Do you mean the phase current sensors? (most likely at the base of the U and W posts)

Looking at it the control section of the controller seems to be too small to work on it.
My guess is that section might be ok, unless the unit simply got hot enough to damage electronics or cause PCB layers to begin separating (doesn't look like it on the SMD areas visible in the pic).

Then I got the idea that it could be possible to replace the mosfet and the capcitor so that it could work with 96v nominal.
Does the software allow this?
 
amberwolf said:
rivvs said:
Hi, so I have a BAC8000 controller that survived a battery fire but the hall sensor do not work anymore
What "hall sensor"? Do you mean the phase current sensors? (most likely at the base of the U and W posts)

Looking at it the control section of the controller seems to be too small to work on it.
My guess is that section might be ok, unless the unit simply got hot enough to damage electronics or cause PCB layers to begin separating (doesn't look like it on the SMD areas visible in the pic).

Then I got the idea that it could be possible to replace the mosfet and the capcitor so that it could work with 96v nominal.
Does the software allow this?
Well my first post was not clear. I speak french so something it is kind of hard to explain something in english. I tested the controller after the fire and it works fine, but the controller can not use the hall sensor from the motor it always fault an hall sensor error. It work in sensorless mode. I believe the software would allow this because I have seen people using 21s with this controller.
 
rivvs said:
I tested the controller after the fire and it works fine, but the controller can not use the hall sensor from the motor it always fault an hall sensor error. It work in sensorless mode.
Is the fault due to the motor itself, or is it the same with an identical replacement motor?

Note that if you have not tuned the controller for the motor it's being used with, it may not work correctly and can have various errors (can even damage the controller or motor under some conditions).

If the fault occurs even with a motor with working hall sensors that you know works with this controller and the controller is tuned for this motor, then my guess is a connector issue at the controller itself caused by the heating during the fire, or electrical damage if the system was powered during the fire and motor phases or battery positive were shorted to hall signal wires at any point during the event, which could have damaged the inputs to the MCU (or circuitry between them) with the excessive voltage. (this damage occurs in axle-wiring-failure events on hubmotors frequently enough).


I believe the software would allow this because I have seen people using 21s with this controller.
Big difference between 21s (88.2v full) and 96v nominal, which is 26s assuming 3.7v/cell, and full voltage would be 109v assuming 4.2v/cell.

So if you don't already know that the software would allow it, and that the LVPS of the controller can handle that kind of voltage (so the LVPS doesn't fail and blow up the brain, etc), I'd recommend verifying this for certain before pursuing that kind of voltage increase, so you're not wasting money on parts that aren't needed. ;)
 
amberwolf said:
rivvs said:
I tested the controller after the fire and it works fine, but the controller can not use the hall sensor from the motor it always fault an hall sensor error. It work in sensorless mode.
Is the fault due to the motor itself, or is it the same with an identical replacement motor?

Note that if you have not tuned the controller for the motor it's being used with, it may not work correctly and can have various errors (can even damage the controller or motor under some conditions).

If the fault occurs even with a motor with working hall sensors that you know works with this controller and the controller is tuned for this motor, then my guess is a connector issue at the controller itself caused by the heating during the fire, or electrical damage if the system was powered during the fire and motor phases or battery positive were shorted to hall signal wires at any point during the event, which could have damaged the inputs to the MCU (or circuitry between them) with the excessive voltage. (this damage occurs in axle-wiring-failure events on hubmotors frequently enough).


I believe the software would allow this because I have seen people using 21s with this controller.
Big difference between 21s (88.2v full) and 96v nominal, which is 26s assuming 3.7v/cell, and full voltage would be 109v assuming 4.2v/cell.

So if you don't already know that the software would allow it, and that the LVPS of the controller can handle that kind of voltage (so the LVPS doesn't fail and blow up the brain, etc), I'd recommend verifying this for certain before pursuing that kind of voltage increase, so you're not wasting money on parts that aren't needed. ;)

I tested with too different motor wich where tuned for this controller before the incident. I tought about the connector but after dissembly the pin are correcly soldered to the board so I believe there is a problem with the circuit of the sensor input. So the controller is useless for my application so this is why I want to mess with it.

Can you tell me waht LVPS means? Also I created this thread to learn and I tough maybe people would be interested to see what the bac 8000 look like!
 
rivvs said:
Can you tell me waht LVPS means?
Low Voltage Power Supply---converts battery voltage to the 5v, 12v, 15v, or whatever else the controller uses internally to run things other than the FETs to the motor phases.
 
amberwolf said:
rivvs said:
Can you tell me waht LVPS means?
Low Voltage Power Supply---converts battery voltage to the 5v, 12v, 15v, or whatever else the controller uses internally to run things other than the FETs to the motor phases.

I googled it and found what it means. I tought about it and and I think that maybe the lvps is feeded by the on input on the controller that receive the 72v to turn it on. So maybe if I was to use 96v on the controller I would need to use 72v on the key on input to turn it on.
 
That could work, as long as no parts in the system powered directly from the FET supply (which would be at the 96v nominal, 109V full) vs the keyswitch/ignition supply (at 72v, 84v full) are incapable of handling that higher voltage.
 
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