Battery Warning Slave 3

[agenor]

We are experiencing a battery warning. We have three SEM modules installed in
our system. After a battery test, the Battery Warning Slave 3 occures. We have
measured the battery voltage and the voltage on the BATT terminal on the Slave 3
board, both voltages are around 13 VDC, so the battery seems to be fine. We
then switched the batteries of the  main board and the Slave 3 board and the
result after the battery test was the same, again the Battery Warning of the
Slave 3 board occured. What could be the solution?

[ident]

The correct way to measure the battery voltage is with the AC off so the battery is delivering the voltage to the Comfort or slave. if the power is on, it is charging the battery at 13.8V so that is not measuring the battery at all

What version of slave board is being used?

Can you check if the battery charging part of the board has 2 transparent bulbs as shown in the picture below. The pic shows the Comfort board but the SEM should be similar except for fewer components

If the 2 bulbs are present as marked in circle, see if the bulbs are burned as this may be caused by plugging in the battery in reverse for a long time
The newer boards do not use the bulbs, a resettable fuse is used which does not burn out

[agenor]

Yes, we have measured the battery voltage correctly.

Our slave board does not have the two transparent bulbs, it is a newer board.

Anyway, we replaced that slave module with another one and the battery warning did not occur again since.

[ident]

Please send the slave back for investigation