First, measure the voltage of each battery pack after it's been charged and has sat for a few hours.
If both are identical, then it's likely the packs are actually the same, and not different chemistries.
If they *are* different chemistries, but still the same Ah capacity and the same full voltage, then the LiFePO4 pack will be larger and heavier.
If they are the same physical size and weight, and the same full voltage and Ah capacity, then they aren't different chemistries (or at least, not Li-Ion vs LiFePO4).
If they are different voltages, but the same physical size and Ah capacity, then the higher voltage unit is probably the LiFePO4 unit (depending on the actual number of cells in series of each pack).
A "48v" LiFePO4 is 16 cells (or groups) in series. It ends up at just over 58v when full, when it's new. It'll end up as low as 52v when full once it ages enough.
A "48v" "Li-Ion" is 13 cells (or groups) in series. It ends up at just over 54v.
A "52v" "Li-Ion" is 14 cells (or groups) in series. It ends up at just under 59v when full.
In the latter case (14s), the same charger could be used on both packs..but I wouldn't recommend it in the former case (13s).
They are physically different sizes (assuming the same size cells). LiFePO4 is also noticeably heavier for the same size cells.
So there are a few ways you can tell the difference.
You can also measure the open circuit voltage of the charger.
john61ct said:
Some mechanism should be ending the charge long before the BMS HVC kicks in. That is supposed to be a fail-safe protection, only used when primary circuitry fails.
Not quite.
The BMS HVC is the normal way the BMS shuts off charging current during balancing. It's a perfectly normal part of the operation.
The BMS *LVC* however, *is* a fail-safe, and the controller LVC should be what shuts off the bike before it ever discharges the battery down to it's LVC. But that's unrelated to this topic.
The charger itself should, of course, be just a high enough voltage to fill the battery, and generally should have a shutoff in it that cuts off charging current once it's dropped below a certain amount (usually for a certain amount of time). So under normal circumstances, it would end the charge cycle itself once the battery is full. (though the BMS may also have shut off charge prior to this).
The danger of using the BMS to end charging always with a charger that is too high a voltage, is that if the BMS fails to shut off charge for any reason (which can happen), the cells will continue to be charged, and the potential for cell damage and even fire exists. How bad it can be depends on how much difference there is between the charger voltage and the pack's actual full voltage, spread across the cells.
