Bms over current reset

chronosgarage · Oct 25, 2020

I need some help; I recently short my Votol EM100 controller. When the controller shorted, the battery is shut off by the bms (possibly by over current protection). The short cause 3 of my cell fuse in the battery to burned. I’ve check the 3 battery condition and found that it’s normal. I then replace the cell fuse in those 3 batteries.

The spec of my bms is 20S 45A (Common port) with 20S9P battery. The battery highest voltage difference Between parallel group is about 0.1v

My problem is the bms do not turn on. I’ve tried to charge it, but it cannot be charged. The is no visible damage on the bms. Is there any reset protocol that i need to perform? Or is my bms is damaged?

john61ct · Oct 25, 2020

If it were properly protected by the BMS OCP then your cell-level fuses should not have triggered, right?

eMark · Oct 26, 2020

chronosgarage said:
I need some help; I recently short my Votol EM100 controller.
The spec of my bms is 20S 45A (Common port) with 20S9P battery. The battery highest voltage difference Between parallel group is about 0.1v
My problem is the bms do not turn on. I’ve tried to charge it, but it cannot be charged. The is no visible damage on the bms. Is there any reset protocol that i need to perform? Or is my bms is damaged?

You've got a 100A controller and a 20S 45A BMS ... see the problem ?
http://www.batterysupports.com/72v-84v-20s-150a-20x-36v-lithium-ion-liion-lipo-battery-bms-p-296.html

chronosgarage · Oct 26, 2020

The controller amp was cap at 30amp though software. The max current draw that i monitor through the software is about 25 to 29 amp.

chronosgarage · Oct 26, 2020

john61ct said:
If it were properly protected by the BMS OCP then your cell-level fuses should not have triggered, right?

Thank you for your reply. Now I understand it. That’s right.

chronosgarage · Oct 26, 2020

eMark said:
chronosgarage said:

I need some help; I recently short my Votol EM100 controller.
The spec of my bms is 20S 45A (Common port) with 20S9P battery. The battery highest voltage difference Between parallel group is about 0.1v
My problem is the bms do not turn on. I’ve tried to charge it, but it cannot be charged. The is no visible damage on the bms. Is there any reset protocol that i need to perform? Or is my bms is damaged?

Click to expand...

You've got a 100A controller and a 20S 45A BMS ... see the problem ?
http://www.batterysupports.com/72v-84v-20s-150a-20x-36v-lithium-ion-liion-lipo-battery-bms-p-296.html

One more thing, my total battery drain is less than 40amp. So I think it is safe. What do you think about my setup?

eMark · Oct 27, 2020

john61ct said:
If it were properly protected by the BMS OCP then your cell-level fuses should not have triggered, right?

chronosgarage said:
One more thing, my total battery drain is less than 40amp. So I think it (45A BMS) safe. What do you think about my setup?

There are good BMSs and not so good BMSs. Next time get a 60A BMS just in case it's not as good of a BMS (60A) as one would hope.

Agree with john that it looks to be a BMS issue, right?

Are you sure your "total battery drain is less than 40amp" ?

john61ct · Oct 27, 2020

chronosgarage said:
One more thing, my total battery drain is less than 40amp.

By this, do you mean

"My system never draws more than 40A peak" for example over a 1sec duration?

or something else?

chronosgarage · Oct 27, 2020

eMark said:
john61ct said:

If it were properly protected by the BMS OCP then your cell-level fuses should not have triggered, right?

Click to expand...

chronosgarage said:

One more thing, my total battery drain is less than 40amp. So I think it (45A BMS) safe. What do you think about my setup?

Click to expand...

There are good BMSs and not so good BMSs. Next time get a 60A BMS just in case it's not as good of a BMS (60A) as one would hope.

Agree with john that it looks to be a BMS issue, right?

Are you sure your "total battery drain is less than 40amp" ?

My battery is build using recycled laptop battery. From the spec of the mix battery used i think the max amp drain is about 4 amp. So 9P equal = 9x4amp = 36amp max battery amp.

Thank you for your recommendation. I will replace the bms with 60amp version.

chronosgarage · Oct 27, 2020

john61ct said:
chronosgarage said:

One more thing, my total battery drain is less than 40amp.

Click to expand...

By this, do you mean

"My system never draws more than 40A peak" for example over a 1sec duration?

or something else?

I was wondering in the battery spec; max amp drain is the max amp the battery can sustain or the battery can spike higher than that in short amount of time?

Based on my calculation the max amp from my mixed recycled laptop battery is 36amp.

john61ct · Oct 27, 2020

Well mixed used cells will only put out a small fraction of any spec.

Actual power capacity depends on time as much as amps

40 amp **peak** can mean "for 3sec" or for fraction of a second.

Usually also need to take heat gain into account.

In any case not a simple single number, subjective variables too common.

Peak rating can be 10x the possible continuous.

chronosgarage · Oct 27, 2020

john61ct said:
Well mixed used cells will only put out a small fraction of any spec.

Actual power capacity depends on time as much as amps

40 amp **peak** can mean "for 3sec" or for fraction of a second.

Usually also need to take heat gain into account.

In any case not a simple single number, subjective variables too common.

Peak rating can be 10x the possible continuous.

Thank you so much for your reply.

Bms over current reset

chronosgarage

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chronosgarage

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