Settings for charger or BMS on lithium

[Burgerman]

For use and in charging.

For e.g in programming, you can set a LOW VOLTAGE CUT OUT in VR2, R-NET for e.g. So you can choose 2 parameters:

a) LOW VOLTAGE setting allows 16V to 22V. Setting to 22V means the last red LED will start rapid flashing and the chair stops when it sees 22V (or 2.7V per cell) on your lithium battery. This is around 98 percent discharged). I do not use this and mines set to 16V as I want to decide when it stops! I would rather destroy a battery and make it home. But if you want to protect the battery it will certainly help. And cut in a fraction before a GOOD QUALITY and BALANCED battery drops below the permanant damage point.

b) LOW VOLTAGE TIME. Determines how long the chair can see this voltage before it stops. So under load it can temporarily go below this figure as you climb a threshold for e.g. So set that to say 10 or 15 seconds. (1 to 255s allowed).

[Burgerman]

Study this too. As you roll that battery warms a couple of degrees. This causes the voltage to rise slightly. And it does that as it discharges. So if a balancer in a BMS or a hobby charger allows it to balance cells at this point it will take energy from the highest voltage cell. (so look at that discharge curve). And feed it to the cells that have the lowest voltage.
When between the two red arrows on the flat bit of that curve this means it takes the power from the most discharged cells (because the voltage went UP as the state of charge fell) - and gives it to the cells that are the lowest voltage - which are already more ful!. Actively UNBALANCING the battery more and more.

So do not allow a LiFePO4 charger/BMS to balance at all below 3.45V as it will UNBALANCE the battery.
In the case of an "active" BMS it will be doing so all day long as you roll!

Also setting a 22V limit in the post above this one, means that theres nothing left. Its dropping off a cliff at this point. 2.7V per cell. This is an emergency setting and you shouldnt ever go that low.
This curve also shows why you cannot determine the battery STATE OF CHARGE by measuring its voltage. That discharge curve may also slope the "correct" way depending on internal temperature rise and the RATE or charge or discharge.