Does JBD bms have auto recovery after LVC?

[Mib896]

If the bms cutsoff due to low voltage on a cell at night, does it resume charging automatically once the panels start generating? Or do you have to manually reset it?

 

[sunshine_eggo]

If the bms cutsoff due to low voltage on a cell at night, does it resume charging automatically once the panels start generating? Or do you have to manually reset it?

Depends on the system. In most cases, the system must see a battery voltage to start charging. If the protection voltage is reported as notably lower (3V or such), then no, it won't.

With a Victron MPPT, they can operate off their panels alone and will apply absorption/float voltage to the battery terminals and will start charging in most cases. Others may have this feature, but I'm not aware of them.

BMS LVD is to be avoided at all costs. Best to have the loads cutting off at higher voltages.

 

[Pierre]

If the bms cutsoff due to low voltage on a cell at night, does it resume charging automatically once the panels start generating? Or do you have to manually reset it?

On the JBD it will only disconnect the load side but will still allow charging. Once the LVD recovery setpoint is reached , the load side will be turned on again.

 

[sunshine_eggo]

On the JBD it will only disconnect the load side but will still allow charging. Once the LVD recovery setpoint is reached , the load side will be turned on again.

It will allow charging, but it reports a very low voltage, which may prevent chargers from operating. Not all chargers will even acknowledge a battery measuring 3V.

 

[Mib896]

On the JBD it will only disconnect the load side but will still allow charging. Once the LVD recovery setpoint is reached , the load side will be turned on again.

Awesome. That answers my question. Thank you. I will go ahead and place the order.

 

[Pierre]

Awesome. That answers my question. Thank you. I will go ahead and place the order.

The scenario is as follows : Normally battery terminal voltage will be around ( 4 x 3,35 ) 13,4v. Should one cell trigger a LVD at 2,8v , the pack voltage is still at 12,85v. Whatever charger you have will respond to this and start charging the pack. Say the LVD reset point is set at 2,9v , the BMS will turn the output on again at around 12,95v. This is one of the main functions (amongst others) of the BMS. You can also set the battery LVD at around 11,6v ( what I use ) .

 

[sunshine_eggo]

The scenario is as follows : Normally battery terminal voltage will be around ( 4 x 3,35 ) 13,4v. Should one cell trigger a LVD at 2,8v , the pack voltage is still at 12,85v.

This statement has been demonstrated incorrect on many many occasions. This behavior may vary between brand and model, but it doesn't take much searching to find "OMG MY BATTERY IS READING XV. IT WON'T CHARGE! IS IT DEAD?" And the conclusion is that it's simply in LV protection and needs to either be paralleled with another battery or a power supply to get it out of protection.

Here's an example within the last 10 days:

12v LFP now at 5.8V. How screwed am I?

I screwed up. I left my battery at 40% SOC in October in an unheated location and without a charge source. I checked it today and no response via Bluetooth. Voltage reads 5.8v, or 1.45V per cell. This sucks. From what I’ve read, this is into severe damage territory and perhaps it’s toast...

diysolarforum.com

Whatever charger you have will respond to this and start charging the pack.

I personally have owned many chargers that will not charge batteries at very low voltage.

MANY MPPT draw their power from the battery. If the BMS is in discharge protection mode, how can it power the MPPT?

The way to guarantee coming out of LVD is to have a means of "jump starting" the battery with either a power supply, another battery or a Victron MPPT.

 

[Pierre]

You are quoting extremes here. I will not respond further.

 

[sunshine_eggo]

You are quoting extremes here. I will not respond further.

I'm quoting typical.