Jump pack for waking up batteries?

[Bluedog225]

As per title, will a little jump pack wake up a LFP 12 volt battery that’s gone into low voltage disconnect? E.g.: battle born.

If so, I wonder how big the jump pack needs to be?

And while on this topic, how does the battery know it’s hooked up to another battery? Seems like we ought to be able to “wake” it up using a little 14 volt solar panel. For some reason I don’t think this would work but don’t know why,

Similar question regarding the low voltage disconnect of the SOK server rack batteries at 48 volts.

 

[LydMekk]

Have you tried connecting a normal battery charger to it?

 

[N8tronics]

I don't have experience with a battery that gone into LVD, but I think all the battery needs to "see" is 14-15 volts to wake up the BMS, the size/capacity of the battery should not matter. However, it's possible it needs to be actually charged a little so the resting voltage is above the LVD so it stays on, in that case a very small battery could try to deliver too much current to the battery and hurt itself.

If using a solar panel, it might work, but I would be careful the VOC (no load open circuit voltage) is really not over 14-15 volts, it could fry the BMS - so I would measure it first to be sure.

I have some experience with the SOK, when I first got them, I couldn't get them to wake up from standby. I actually have a 48V supply, and that DIDN'T work. I had to apply 52 or so volts to do it. So I imagine that if you attempt to charge those, they will wake up. Hope that helps

 

[chrisski]

IME, it may or may not work.

Although not battleborn for a tripped BMS from a discharge below 10 volts over amp , my 25 ah 8S top brand cells in battery packs sometimes wake up with when I put a 27 volt charge on it, other times I need to get in the battery pack and jump the leads.

Either way Once the battery wakes up with the 27 volt 1 amp charge from the power supply.

 

[Supervstech]

If there is enough amperage available to overcome th low cell voltage, it should reset the bms.
A little solar panel has little amperage above 10V, so likely it would just drop output to cell voltage and fail to engage.
Also...
The voltage eeds to be on the cell side of the bms to jump it, putting power to the load side of the bms likely wont start it.

 

[Rednecktek]

If someone here with time & electrical knowledge were really bored, they could build up a little "Jump Pack" using 18650 batteries and an adjustable DC voltage converter so you could set it to 14v, 27v, 51v, or whatever you needed that would provide just a little voltage to "wake up" a battery without having to rig up AC chargers or solar panels or whatever. Just something the size of a multi meter or so would be perfect.

 

[HighDesertOffgrid]

As per title, will a little jump pack wake up a LFP 12 volt battery that’s gone into low voltage disconnect? E.g.: battle born.

If you are talking about a situation where a charge controller needs battery voltage to begin charging then yes I have done this on a few occasions. It doesn't take much.

 

[Supervstech]

If you are talking about a situation where a charge controller needs battery voltage to begin charging then yes I have done this on a few occasions. It doesn't take much.View attachment 190677

This would work, likely it would take a LOT of 18650's to get the amperage high enough.

 

[Bluedog225]

I ran my battle born down once due to a disconnested panel. Jumped it with the jeep battery. Worked fine.

Just curious.

 

[Rednecktek]

This would work, likely it would take a LOT of 18650's to get the amperage high enough.

Does a BMS need amperage or voltage to wake up? My understanding was even a few milliamps at voltage would do it.

 

[HighDesertOffgrid]

Does a BMS need amperage or voltage to wake up? My understanding was even a few milliamps at voltage would do it.

You may need a large enough current to momentarily reach the LV cut in of the BMS.

 

[Bluedog225]

@HighTechLab

I looked at the SOK manual on the 48 volt server rack batteries. It describes the low voltage disco but the term is not otherwise used in the manual per my word search.

I don’t have anything large enough to wake those up at the remote site.