Bms operation

[frankz66]

Hello everyone, being a beginner I ask a question about BMS . I wanted to know, if any bms mounted on lifepo4, when it goes into protection or better as they say it disconnects the bms, the voltage in the batteries is always present? Only the load is interrupted but maintaining the voltage or on the positive and negative poles no more voltage is read?

 

[DIYrich]

Hello everyone, being a beginner I ask a question about BMS . I wanted to know, if any bms mounted on lifepo4, when it goes into protection or better as they say it disconnects the bms, the voltage in the batteries is always present? Only the load is interrupted but maintaining the voltage or on the positive and negative poles no more voltage is read?

Voltage is present AT THE BATTERY. No voltage after the BMS.

 

[sunshine_eggo]

Voltage is present AT THE BATTERY. No voltage after the BMS.

Some BMS give some arbitrary very low voltage... 2V, 3V, 6V, etc.

In many cases, the above condition PREVENTS charging because the charger is expecting a higher voltage. Placing in parallel with another battery, or charging with a power supply, or a charger that will charge even if battery voltage is out of spec may be your only option for getting the batteries out of protection.

Due to the above, BMS discharge protection should be avoided at all costs unless you already have tested means of recovering them.

Sometimes when charge protection is triggered, some BMS will report something in the 12.5-12.9V range until they are discharged to where charge protection is disabled and then voltage "jumps" up to actual.

 

[frankz66]

Some BMS give some arbitrary very low voltage... 2V, 3V, 6V, etc.

In many cases, the above condition PREVENTS charging because the charger is expecting a higher voltage. Placing in parallel with another battery, or charging with a power supply, or a charger that will charge even if battery voltage is out of spec may be your only option for getting the batteries out of protection.

Due to the above, BMS discharge protection should be avoided at all costs unless you already have tested means of recovering them.

Sometimes when charge protection is triggered, some BMS will report something in the 12.5-12.9V range until they are discharged to where charge protection is disabled and then voltage "jumps" up to actual.

In order to avoid the break, what can be done and how can it be done?

 

[frankz66]

Voltage is present AT THE BATTERY. No voltage after the BMS.

So from what you wrote, the regulator shouldn't burn out....

 

[upnorthandpersonal]

If you have a MOSFET BMS like the JK, if the BMS goes into charging disconnect protection due to a cell over-voltage, the battery voltage is still present at the output, and discharge is still enabled. Only when the disconnect protection due to cell under-voltage occurs will the voltage no longer be present, but any decent MPPT controller should still be able to charge it (the charge path remains open, only the discharge is prevented).