BCU-NEV-XXC MANUAL
1.0
If storing for more than a month the BMS should be off and also the main battery isolator (which
supplies power to the BCU also) should be off.
If the battery is over-discharged and the charger will not enable then a temporary override
is to press and hold the on-o
ff
button. Do this only once for maximum 60 seconds to see if the
battery will come up to minimum voltage.
If it does not then do not persist, check the battery.
Error Messages
The BCU will flash an error signal if there is a problem.
' 0 = STATUS- OK(0), CLOSEDOWN MODE(1)
' 2 = CELL MODULE CURRENT LOOP - OK (0), BROKEN LOOP ERROR (1)
' 4 = BATTERY UNDER-VOLTAGE FLAG - OK (0), UNDERVOLTAGE (1)
' 5 = BATTERY OVER-VOLTAGE FLAG - OK (0), OVERVOLTAGE (1)
' 6 = CURRENT LIMIT - IN RANGE (0), OVERCURRENT (1)
About Pre-charging and Voltage Trimpots
The BCU has an automatic precharge circuit that precharges any capacitors connected on the load
side of the relay.
In this way it protects the main relay from welding shut due to high inrush currents when switched
on. If the precharge lasts too long (>15 secs) the relay will switch on anyway, so this must be
accounted for with any application.
Initially a current limiting resistor is switched in the circuit an the BCU monitors the load voltage
and compares to the battery voltage.
Once the load reaches 90% of the battery voltage the main relay will be engaged.
Using the OLED monitor the LOAD voltage can be trimmed to be correct simply by measuring the
actual voltage and comparing it on the screen.
There is no easy way to trim the BAT voltage pot. It needs the factory programming cable to be in
place.
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