Reusing Leaf sensor wiring, make sense or not?

[HollySprings]

Has anyone tried to (re)use the Nissan Leaf existing voltage tap wiring and plastic covers in their 14s2p reconfigurations? Looks to me like just removing the bus bars between modules 7 and 8, 14 and 15, then 21 and 22... and putting in a terminal tap would work for the back. For the sides I'd do the same and add taps, with two extra modules to make two 14s2p sets from each of the left and right sides. I'll use the existing integrated wiring harness and the extisting plug will connect to two BMS (14s) modules. The tie-in part will be custom made, but most everything else will be stock.

For the back 24, I'll have three sets of 14s2p with the same terminal change (where bus bar removed) and the wiring connector leading to three BMS harnesses. I'll remove three extra modules in the stack and use them on the sides, along with a spare. The total package of 48 modules (+1 extra) will then be seven 14s2p batteries, each 48V and inverter ready, with about 24kWh capacity per set (per car.)

Physically, I envision the packs on a three shelf rack, roughly the width of the 24 pack assembly, stacked between two Sunny Island 6048-US inverters for a split phase AC setup. I plan to use an open source BMS, DIYBMSv4. I have the controller boards and several cell monitor boards but am waiting on some parts.

An alternative to the 7 x 14s2p setup is a 14s14p configuration with all new bus bars, covers, a different BMS to handle larger amperage. I don't think it is feasible to reuse the OEM BMS but don't know enough about it to really conclude either way.

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[Mike90250]

Wire your bombs up ! Seriously - if you have to ask, you should not be mucking about in the innards of BIG HIGH VOLTAGE BATTERIES

danger do not touch hurt while you die.jpg

[Ampster]

Has anyone tried to (re)use the Nissan Leaf existing voltage tap wiring and plastic covers in their 14s2p reconfigurations? Looks to me like just removing the bus bars between modules 7 and 8, 14 and 15, then 21 and 22... and putting in a terminal tap would work for the back. For the sides I'd do the same and add taps, with two extra modules to make two 14s2p sets from each of the left and right sides. I'll use the existing integrated wiring harness and the extisting plug will connect to two BMS (14s) modules. The tie-in part will be custom made, but most everything else will be stock.

........

I have 54 Modules in six stacks of nine . I think that would be described as 18P12S at the cell level because each module consists of two cells in paralell and two of those buddy pairs in series. (2P2S). I did not use any of the Nissan wiring harness or voltage tap wires. I used 3/4" copper custom buss bars to connect the modules together in sets of nine. I used 1/2" copper for the center connector which did not carry much current but was needed for the BMS. I use one BMS which sees the pack as 12 cells. I rarely turn on the balancing function of my BMS because with that many cells in parallel there is very little difference in voltage at the top. For that reason I do not need a high amperage BMS. I use it mostly for reporting and monitoring. My inverter takes care of the low and high voltage cutoffs. It is not feasable to use the OEM BMS because it is expecting to see 48 modules in series. {400 volts)

Because my pack is a mix of several vintage modules I see some voltage drift if I discharge past 50% which is a rare occurrence. Part of that pack was from a complete car and once I got the cover off the pack I disconnected the larger buss bars connecting the modules together. That way there was no longer the potential for high voltage. Since the modules are 8 Volts I made sure no more than 8 were left in series as I disassembled the pack which kept the DC voltage at any point less than 70 volts. There is still some large Amperage so you still need to be careful with tools to not short the module posts.

[HollySprings]

Mike, thanks for your reply. I understand your concern and your post. As you can see from the interim picture that I posted our electrician had reduced the "innards" by removing the connecting bus bars (two of them visible on top of the right side pack) and cables, isolating each battery pack. At that point, we didn't yet reduce the monolithic battery to eight 48v (12S2P) packs. As you state, people should have an electrician do the isolation. I'll leave it at that.

Ampster, thanks for the insight. We bought the whole Leaf to keep modules at the same 'vintage'. I wanted to try to control some variables (age, condition) as much as possible, and figured the integrated product was the best way to do that. Besides, the cost per module was about half the cost of buying blocks (e.g. 14) of modules and all the pre-wiring is already done.The bottom line is we are going to reuse a lot of the OEM parts, specifically the sense wires and harnesses, pack assemblies, integrated plastic protective covers, and OEM terminal posts. We'll end up with the 12S configuration rather than 14S that I posted, so scratch adding modules or jumpers between the OEM harnesses. The SMA SI products don't seem to care. We have identified all the voltage sensor locations relative to the harness pinouts for mapping to BMS support. We aren't using the 2x48s OEM BMS, which we didn't expect to be able to use. One thing I like about reusing OEM parts is that, save for 30-60 minutes of electrician setup, all the conductive material is covered, and almost all of it by OEM material.

I guess time will tell, but at this point at least I can answer the question I posted.