Hi All,
Can I use one of the lithium superpacks as a start battery? What would the CCA rating be on one of them and would the integrated BMS allow it to provide the required 'pulse current' ?
Thanks
asked
Can I use a small lithium battery as a start battery?
Hi,
I dont know much about lithium batteries, but when you start a car/truck the amps can go over 100a ( i had a 120ah battery in my car when i was young ;-) )
So when a car starts it take a lot of energy to start it, when it runs , not that much anymore.
I dont know if you battery can deliver that much energy in a couple of sec.? ( what are the specs on the BMS? )
Not without (warranty voiding) modifications to the victron superpacks I'd suspect.
The discharge spec looks to be consistent with a power FET rather than a contactor for the internal switch, which means that attempting to draw cranking current from these batteries is not a good idea and may very well let out the magic smoke.
https://www.youtube.com/watch?v=mXwJpPxEJ2E ... the answers are often out there if one only takes a minute to search ...
Just to be clear, the video showed a super-b starter lithium, which does not appear to have an integral BMS switch. The OP was about the victron lithium superpacks which does have an integral BMS switch.
The raw LiFePo can certainly capable (if designed appropriately by the mfg), but the original question seems to be around whether the integral BMS (switch) would bottleneck the output.
Hi all,
Even when using a LifePo4 i suspect we'd have to make sure the cranking requirements are less than the indicated max discharge current (i.e usually about 2x the battery capacity)?
In short yes. However, the assumption around max discharge current being 2x battery capacity is potentially not valid for LiFePos with an integrated switch.
I suspect if the power surge does not exceed these levels, a BMS should in theory cope. I'd be concerned if cranking requires more than a 2-3s at a time.
