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Nissan Leaf charger vs BMS questions

1651 Views 2 Replies 2 Participants Last post by  rev0
Hi all,

I've been looking into the BMS Leaf pack (Gen1) and try to figure out how it controls the charger or charging process. Without having access to a charger myself but just the pack with BMS i can only 'see' whats coming out of the BMS but i'm missing whats going on at the chargers end.

Can someone enlight me on this matter, what CANmsg is sent out by the charger, read by the BMS and vice versa ?


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259 Posts
Discussion Starter · #2 · (Edited)
Sofar I have gathered a lot of info and diagnosed the following CANid packets sent automagically by the BMS:

0x1DB, contains amps and volts and some status bits
0x1DC, contains capacity in kW and possibly some charging info
0x55B, contains SOC and some other pack voltage
0x5B9, GOMFuelbars
0x5C0, some charging info ?

With the 0x79B/0x7BB challenge/response queries individual groups of data for cell voltages, temps and shunt bits can requested. Each group has their own index and response in several data frames:
0x01 pack health, 6 frames
0x02 cell voltages, 29 frames
0x03 voltages ? , 5 frames
0x04 temperatures, 3 frames
0x05 ?? 11 frames
0x06 shuntbits, 4 frames

Some findings:

Looking at the shunt bits it seems that the pack is balancing when power is applied to the BMS but without power to pin 21 IGN input.

When pulling the service plug or removing the main connector a bit is set in 0x1DB
Only when the service plug is present full pack voltage is present in 0x1DB. The individual cell voltages can always be read, even without the service plug plresent.

I assume this bit is also read bij other ECU's to decide what to display or start charge or alike.

Since i dont have access to an original charger i have connected a Brusa charger and will initiate a low current charge to see what happens when the shunt bits are set AND to discover if any other bits are set when shunting takes place. I assume that the charger is trickeled by the BMS when shunting takes place. Or maybe theres even a special CANid for it ?? Not sure if the BMS will 'tell' the charger how much current or voltage it can supply.

· Registered
31 Posts
This is just speculation from what I've read any my experience with monitoring charging/normal use with Leaf Spy on my Leaf, but I think the balancing is just going on all the time with no special connection to charging, and charging termination is determined by the BMS when any cells reach the termination threshold voltage (around 4.125V?). The balancing current is only 10mA, so it's really not going to make a dent when you consider charging in the kW range. Lots of info on the BMS here if you haven't already found it:
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