restarting a flat lithium (bms shutdown on empty)

[leon.davibe]

i always thought the easiest is to have an old 12v power supply from an old rechargeable light or modem handy
but in this video they try a plain old 9v battery

 

[leon.davibe]

now naturally a 48v system is a bit more tricky, but i suppose if you can get your hands on an old printer power supply , that are normally like 30v it may be enough , or you could get yourself a step up converter with a battery that steps it up to whatever is needed to restart a 48v battery and some lithium cells that won't self discharge if thrown in a drawer

ie like one of these

600w Step-up Boost power module

botshop.co.za

DC-DC 8.5-48V To 10-50V 10A 250W Continuous Adjustable High Power Boost Power Module Constant Voltag | bobshop.co.za

Buy DC-DC 8.5-48V To 10-50V 10A 250W Continuous Adjustable High Power Boost Power Module Constant Voltag for R177.00

www.bobshop.co.za

connected with a holder like this

18650 Battery Case

This 1 Section 18650 Battery Case holds one single 18650 battery. We can also fit 2 x CR-123 batteries in this holder. CR-123 lithiums are 3V each, thus 2 of them in a series will give you 6V

botshop.co.za

 

[impracticaldogg]

I thought that the"cold start" function on an inverter was another way to do this. Or have I got the wrong end of the stick?

 

[leon.davibe]

I thought that the"cold start" function on an inverter was another way to do this. Or have I got the wrong end of the stick?

The cold start means it can start without eskom present ie just from battery

Or that is the way i always understood it to mean

So if the battery is in over discharged shutdown it won't start charging too dependant on device as many want to see battery present before charging so apply no volts/charge

ie battery waits for charger and charger waits for battery

And hence where the jumpstart comes in

You apply a voltage to terminals the bms see it switches on and same with inverter /charger

 

[RedViking]

Battery place in town will get it going.

 

[leon.davibe]

Battery place in town will get it going.

i have always just jump started it at home

my first battery was a diy
so i just used a plier to touch the cell negative to the negative on the outside of the bms giving it the voltage from cells , when eskom was back bms switches on inverter would see it start charging and back in business

only happened a few times until i sorted my balancing and got to know what i can run in x hours of load shedding to not go all the way to empty again