ProgressiveRC Multi4 FMA Cellpro - Manual (Page 11)

11
Charging two parallel-connected packs using two chargers
Multi4 Charger firmware versions v1.58 and later allow for reliable charging when using two
Multi4 Chargers to simultaneously charge parallel-connected battery packs.
The Multi4 handles charging of two packs wired in parallel. An example would be two redun-
dant flight packs used in gas powered airplanes. Typical configurations would be, for example,
two 2s A123 batteries wired in parallel, or two 4s or 5s NiMH batteries wired in parallel. In these
types of installations, switch harnesses should break each of the positive (red) wires between the
battery packs and the airborne electronics (the red wires are physically disconnected from each
other) during charging, while the negative (black) wire stays connected. Charging both packs
simultaneously requires two Multi4 Chargers connected to two separate power sources that do
not have a common ground.
To charge two parallel-connected packs using two Multi4 Chargers:
1. Disconnect the two positive (red) wires between the parallel-connected packs. This is usually
accomplished by independent switches.
2. Depending on the pack chemistry, connect either the node connectors of each of the packs or
the main discharge wires to two Multi4 Chargers. If charging non-balanced, be sure to select
a non-balanced preset (and remember for LiPo packs the Multi4 only supports up to 2s non-
balanced charge at a maximum of 1A charge current; this restriction does not apply to NiMH
or A123 batteries).
3. Connect the chargers to two separate power sources that do not have a common ground—
two lead acid batteries, for example.
CAUTION: AC power supplies often have a common ground through their AC plugs,
and therefore cannot be used in this charging situation. Always perform a continuity
check to assure the power sources used to charge two parallel-connected packs are not
connected through their grounds or negative output terminals.
4. Follow the Start Charge instructions to initiate charging on one of the packs.
5. Within 10 seconds, initiate Start Charge on the other charger. Failure to start the second char-
ger within 10 seconds could result in a Safety Code indicating “Series Charge” condition. If
this occurs, cycle power to both chargers and try again.