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Here is a picture showing how equipment shall be connected to BMS4S. Please note that there are
no switches or fuses shown in the picture. All wires leaving a battery should have a switch and must
be properly fused close to the battery if there is a slightest risk that it can ever create a shortage or
overload, but that is outside the scope of this manual and you will have to find descriptions on how
to do this elsewhere. So, let us instead discuss how the equipment in the picture shall be connected
to BMS4S. We’ll take them one by one, but first a warning: NEVER C12 V BEFORE – AND B0
ARE CONNECTED. If you want to test the BMS4S before installation, connect – and B0 to battery
minus, and then +12 and B12 to battery plus (and then command wm=2 to tell BMS4S that only 12 V
is connected).
1
You need five cables between BMS and the LFP cells. Mark them in one end with labels:
B12, B9, B6, B3 and B0. Start connecting the B0 wire in B0 on BMS4S and then connect it
to the battery minus terminal. Continue with B3 which shall be connected to + side of
the first cell. B6 to the second cells + terminal. B9 to the third, and B12 to the fourth
cells + terminal. Check each wire one extra time before connecting it to the battery.
2
Open up the wires between the battery and the main panel and connect the latching
relay so that it can disconnect all user equipment when a low voltage situation occurs.
Then connect the wires between the relay and BMS as in the picture, i.e. the wire that
switches off the relay to the Load OFF terminal, and the one switching it on to the Load
On terminal. The common wire is connected to ground. The control terminals for driving
the relays on BMS4S are of MOSFET type, and can drive 11 A momentarily and 3 A
continuously
.
You can of course use high power relays like Bluesea 500 A if you have
equipment with a high demand for power.