Waking up a shutdown Daly BMS

[arthur49]

Sterling Power 100Ah Lithium battery, Votronic 25A mains charger, Votronic 50A B2B

Run battery down to BMS shutdown, set to low volt 10.8v (I know it can be set to go lower than this). B2B would not waken it up despite saying it could!
I have a Ring Power Pack which I believe can waken it up, by applying its 12v output to lithium terminals with engine running, it should switch back to life and accept charge. But since the battery terminals were showing 10.8v, if I apply the power packs 12v I end up with 22.8v at terminals, potentially shutting down BMS by over-volts shutdown? Am I over-thinking this/wrong? Or maybe the capacitors in BMS were holding volts high but it would seep away to almost zero?
(It is going again, the mains charger started it right away, but if this happens off-grid I'm stuck!)

 

[autorouter]

Think of it like this. Suppose you had two ordinary lead-acid batteries, one at 12.0V and one at 12.6V. If you connect them together, positive to positive, negative to negative, that makes them into a parallel connection. The two voltages will be equalised instantly, and the higher voltage battery will pass amps to the lower voltage battery until they are both equally charged. Soon the amps will drop ro zero, and the volts will stabilise at about 12.3V.

Current will flow from the higher voltage battery to the lower voltage battery, until the two voltages are equalised.

If you apply the power pack like this, positive to positive, negative to negative, it will boost the battery voltage to somewhere between the existing 10.8V and the power pack 12.8V. With any luck that will be enough to get the BMS to turn on.

 

[arthur49]

Just an update on this issue. I ran down batteries individually until BMS shut them down. Started engine and Votronic 50A B2B would not waken them up. So not a fault with BMS as surely both could not be faulty?
Next step was to try "jump starting" BMS. I took the input feed to B2B from starter battery and via cable with 5A fuse connected to positive terminal of sleeping BMS. Started engine and BMS clicked and wakened. Charging nicely now via B2B.
So 12v Planet have agreed to take back for testing and repair (2 year warranty)

 

[Hoovie]

Just an update on this issue. I ran down batteries individually until BMS shut them down. Started engine and Votronic 50A B2B would not waken them up. So not a fault with BMS as surely both could not be faulty?
Next step was to try "jump starting" BMS. I took the input feed to B2B from starter battery and via cable with 5A fuse connected to positive terminal of sleeping BMS. Started engine and BMS clicked and wakened. Charging nicely now via B2B.
So 12v Planet have agreed to take back for testing and repair (2 year warranty

It is not that surprising to me that the B2B would not waken the Batteries. When there is no voltage detected on the Output, a charger will often not start up.

 

[arthur49]

It is not that surprising to me that the B2B would not waken the Batteries. When there is no voltage detected on the Output, a charger will often not start up.

True.
But the Votronic is sold with the ability to waken a sleeping BMS. (I have the 25A Votronic mains charger and it wakens a sleeping BMS no prob)

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[Bessy765]

our transporter lithium were run down until the bms kicked in it took the Victron 12/2000/80 inverter charger 15 mins to wake them up.