BCU-PPAK INSTALLATION MANUAL 1.0
How it works - Usage
The BCU per orms a number o unctions:
1) It monitors the battery voltage, i the voltage alls below 11.6V or rises above 15.0V (4 or 5 red LED lashes) or more
than 15-20 seconds the relay will open. Then will be no LEDs and the BCU will revert to a low power mode.
2) It monitors the BMS cell module loop. I any cell goes below 2.5V or above 4.0V (2 lashes red LED) or more than 15-
20 seconds the relay will open. Then will be no LEDs and the BCU will revert to a low power mode.
3) I the battery voltage is below 11.6V or above 15.0V and the BMS cell loop signals an error on one cell the relay will
immediately open, no delay. Then will be no LEDs and the BCU will revert to a low power mode.
The BCU is operated by pressing the ON/OFF button on the ront.
- One press to switch on
- One press to switch o
- Press and hold to override and engage relay a ter a dropout. Use this only i necessary and only to enable charging.
The BCU ON/OFF button has a Red LED to indicate that the relay is switched ON.
This LED will lash to indicate battery error conditions.
- Two red lashes, one or more cell modules is registering a cell ault. (< 2.5V or > 4.0V)
- Four red lashes, low battery voltage, <11.6V
- Five red lashes, high battery voltage, > 15.0V
- No LEDS, BCU has dropped the contactor and switched itsel OFF.
The relay is a special type called a magnetic latching relay. It consumes no power when switched on. The downside o
this is that it can remain on i power to the BCU is removed or i the BCU ails or any reason. Check that the relay is op-
erating correctly occasionally by switching o and on the BCU.
S ME L ADS AND CHARGERS HAVE INTERNAL CAPACIT RS WHICH DRAW LARGE INRUSH
CURRENTS WHEN C NNECTED. THIS MAY CAUSE THE RELAY C NTACTS T FUSE CL SED. SUITABLE
PRE-CHARGE CIRCUITS SH ULD BE INC RP RATED IN THIS CASE.
D N T DISC NNECT P WER T THE BCU WHILE THE RELAY IS IN THE N STATE, battery protec-
tion will be removed.
I the BCU cuts o the battery during discharge the battery is most likely nearly empty. DO NOT RESET AND CONTIN-
UE DISCHARGE! Reset and charge the battery immediately.
I the relay is pulsing on/o that would mean it is hitting the low voltage threshold under load. More likely on cold days
and with cold batteries.
Note that the 11.6V cuto threshold equates to approximately 2-5% remaining battery capacity, more or less. The battery
should be considered to be lat at this level to allow or a sa ety bu er.
Note that even when switched o the BCU consumes a small parasitic current. It will take some months to drain a ull
battery at this rate but it is best to either leave the battery on continuous loat charge 13.6-13.8V or to disconnect the
BCU i the battery is to be stored or long periods.
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