On 06/05/2018 03:20 PM, Martin Gregorie wrote:
On Tue, 05 Jun 2018 14:35:42 -0600, kinsell wrote:

Not sure what a "proper" BMS board is. There are a variety of functions
that may be included, the data sheets tend to vague on what's in there.
See Wikipedia for a primer.

I'd say it must have these functions:

- cell-balancing charging management
- low-voltage shut-down
- some sort of high-current limiting
This need not be expensive: I'd accept built-in replaceable fuses
and holders or solid state current limiters that temporarily
disconnect the battery when the load becomes excessive.
Neither are exactly what you'd call new technology.

Not new technology, but the switch needs to handle the maximum current
that the battery can be called on to deliver. Many applications are
going to involve more than an amp or two to power a sailplane panel.




If the battery can disconnect itself from the terminals in the event of
excessive discharge current, too high of charging voltage, or too low
voltage on discharge, then it requires some high-current switches to do
the job.

Inexpensive built-in fuses can handle that perfectly well.


Fuses can handle the overcurrent, but disconnecting on high or low
voltage isn't going to be cheap, if the battery is rated for high current.

Richard had an interesting post a while ago, where he accidentally used
the wrong charger on an FLP, and battery was destroyed due to swelling.
So much for the idea of a BMS protecting the battery.

-Dave