Ben Goren via EV wrote:
_Every_ charger has a battery management system.
Only if you define BMS as "Bare Minimum System".
A normal battery charger can only see the total pack voltage. It has to
make all its determinations based on nothing but this voltage, and maybe
the apparent total pack resistance (how the voltage changes as a
consequence of the charging current).
It doesn't know the voltage of individual cells, or what kind they are.
It doesn't know the pack's amphour capacity, its temperature, age, or
condition. *If* the pack is perfect and everything goes according to
play, it will work.
But if anything goes wrong, the charger will happily overcharge the pack
to death. If destroying thousands of dollars of batteries isn't bad
enough, it can also start a fire!
Therefore, pretty much all commercial products that use more than a
single lithium cell will monitor every cell individually. Their voltages
will all be monitored, so the charger can be shut down if any cell has
an abnormal voltage. There will also be overcurrent protection in every
cell, multiple temperature sensors, and other safety devices. All this
adds significant cost and complexity to the charger -- but manufacturers
have found that it's necessary to prevent early battery failures and fires.
Building an Ev without a BMS is equivalent to building your house
without circuit breakers or fuses.
--
The greatest pleasure in life is to create something that wasn't
there before. -- Roy Spence
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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