I know there has been a number of threads related to this subject, but is there a definitive way of achieving this; specifically:
- How often should it be done?
- Can you only do a balance at 100% on a granny charger?
- Can you do a balance at 100% with a home 7kW charger?
- Can you balance on higher output chargers or not?
Many thanks for any replies.
Some of this depends on battery chemistry: if NMC (long range) then more fiddling & pre-planning; if LFP (short range) then whenever & however you like, mostly.
You can practically
only balance on an AC 7kW charger, also granny but that would usually take far too long to be useful or convenient. You cannot balance with a public DC charger.
I’ve owned both a gen 1 ZSEV (NMC) and a gen 2 ZSEV (LFP). The NMC for this or any other EV requires charging to 80% or so on a regular basis, then to 100% & balance every six weeks or so. I found that gets to be a PITA, this EV or any other NMC EV for that matter.
With the gen 2 ZSEV LFP, just charge & balance whenever I like, but usually in practice this is for less than 50% and most regularly from 30% every fortnight (mostly urban driving). The same here applies on say a short range Tesla (LFP) vs a long range (NMC). In the case of BYD, all models are LFP blade batteries.
Re. the balancing question: I found that with my gen 1 ZSEV (NMC) that the balancing phase could often take quite some time once beyond the 100% full charge, typically 105mins. Others report even longer times than this, depending … It also would lose a little range in winter. With the gen 2 ZSEV (LFP) the balancing is usually only a few minutes beyond 100% charge and seems to be very consistent. Also it has never lost any range over the last year or so & consistently charges to a full 320km.
Balancing (aka equalisation) always takes place after a full 100% charge on any chemistry. At this point the power draw drops from full whack (32A 7kW single phase here) to a trickle charge. That balancing phase & monitoring of this can be variously observed, say on the wall box software, on an OBD dongle, or on the car’s front indicator charging port. When the lights go off, its done.
I charge my car to 100% and balance regularly every two weeks from lowest at 20% to 100% and balance. This is always fully done within the six hour overnight off-peak period between 12am-6am. A long range NMC battery will take far longer under the same conditions & so would be inclined to balance from a higher starting point given the timing.
Then on the other hand, some EV manufacturers like BYD suggest running the battery down to a lower SOC before balancing those cells. YMMV, but as I said, I found NMC to be a bit of a PITA over time. This will change no doubt with some overdue battery chemistry upgrades coming shortly from CATL and BYD.
