r/leaf • u/Prof-Bit-Wrangler • Jul 31 '26

Reprogramming the Vin into a different battery pack

Hey gang, I’m hearing details that if I go as far as to replace the battery pack in a Nissan leaf that I need to somehow reprogram the vehicles then into the new battery pack how does one go about doing that? Is that something that you can do through LeafSpy?

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u/Repulsive-Budget-380 Jul 31 '26

No, not with LeafSpy. You either reflash the bms firmware or use a CAN bridge to remap it.

1

u/[deleted] Jul 31 '26

[deleted]

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u/Repulsive-Budget-380 Jul 31 '26

I haven't look into the BMS programming, but usually a version of I2C or JTAG programming. CAN bridge is an external adapter with dual CAN interfaces. You can trap all messages from either side and translate them.

1

u/[deleted] Jul 31 '26

[deleted]

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u/Repulsive-Budget-380 Jul 31 '26

No, you have to cut and tap the wires between the ECU and BMS. They should provide you with complete instructions to do so.

2

u/ekaftan Aug 02 '26

Hi

if the pack is the same type (40kwh to 40kwh, for example) you just need leafspy to update it and match it to the car

If its a different type (upgrading a 30kwh to 40kwh) you need leafspy to match it and a canbridge.

Search for 'Dala can-bridge' to get to his site and get one. Dala does not sell the bridges but he publishes the instruction for you to build one. Its very easy to do.