Nissan Leaf BMS

Topics concerning OEM and open source BMSes
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Re: Nissan Leaf BMS

Post by jerrykco »

johu wrote: Thu Mar 17, 2022 7:54 am Sorry, should have been more specific: STM32F1 board - stm32-car doesn't compile for Cortex-M4. So look for Bluepill for example
Hi Johannes, Still waiting on the STM32F1 but I have awesome news! My battery pack is working and WolfTronix PS2 is working also. I was at v1.0. Wolf made a change at v1.2 that fixed a timing glitch. I upgraded to v1.2 and everything is now working. So, my rewire job for the 24 pack sense wires in my rebuilt 2ed 24 pack to match the two 12 packs is 100% working. Whew! Really good news. I still want to also get the STM32F1 Working. I'll need a digital canbus speedometer!
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Re: Nissan Leaf BMS

Post by jerrykco »

Hi Johannes,
I received the STM32-F1. Now I need to figure out how to use it. Is there a How to for STM32-car?
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Re: Nissan Leaf BMS

Post by johu »

It compiles like any openinverter project, see README: https://github.com/jsphuebner/stm32-car

Once connected to a Leaf BMS it will show some values like batmin/batmax
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Re: Nissan Leaf BMS

Post by wjdijkstra »

Hi everyone, good to find this collection of smart people here :)

Now I'm in the process of "getting smart" when it comes to EV's and bms-es etc, so hope I can pick something up from you guys!


Here's my question: Would I be able to use a 24 kwh leaf battery pack at half the voltage and double the amp-hours (so going from 96S2 to 48S4) and still be able to use the leaf BMS? Obviously re-arranging the busbars :)
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Re: Nissan Leaf BMS

Post by Bratitude »

wjdijkstra wrote: Tue Sep 20, 2022 2:32 pm


Here's my question: Would I be able to use a 24 kwh leaf battery pack at half the voltage and double the amp-hours (so going from 96S2 to 48S4) and still be able to use the leaf BMS? Obviously re-arranging the busbars :)
your not gaining any amp hours if your not adding any additional cells.

But from my understanding, halving the pack and doubling the bms leads dose work.
https://bratindustries.net/ leaf motor couplers, adapter plates, custom drive train components
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Re: Nissan Leaf BMS

Post by wjdijkstra »

Thanks for your reply, but 60Ah from a set of batteries at 360 volts will become 120Ah at 180 volts. You're thinking of KWh => 360volt x 60Ah = 21kwh = 180volt x 120Ah :)
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Re: Nissan Leaf BMS

Post by wjdijkstra »

any answer on my above question?
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Re: Nissan Leaf BMS

Post by vwbrady »

wjdijkstra wrote: Tue Sep 20, 2022 2:32 pm Here's my question: Would I be able to use a 24 kwh leaf battery pack at half the voltage and double the amp-hours (so going from 96S2 to 48S4) and still be able to use the leaf BMS? Obviously re-arranging the busbars :)
at that point you'd only be using 48 of the BMS cell measurements. Not sure anyone has tried that. I doubt it works.

If you're considering leaving the cell taps as is, then idk what would happen. You could just be measuring the same set of parallel cells twice, or you could be shorting through the BMS.
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Re: Nissan Leaf BMS

Post by johu »

The Leaf BMS consists of two halfs. So you can measure 48 cells twice. Woftronix has some videos up on youtube about it.
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Re: Nissan Leaf BMS

Post by wjdijkstra »

I'm looking into the Wolftronix setup now, thanks for the pointers!
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Re: Nissan Leaf BMS

Post by wjdijkstra »

The leaf bms only balances while charging right?
Could I add a cheap active balancer (like https://www.aliexpress.com/item/1005003345896765.html) or would It get in the way of the bms...
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Re: Nissan Leaf BMS

Post by johu »

It always balances while active. I wouldn't touch it. Balancing is a super overrated topic. A pack can stay balanced for years, that's the order of magnitude you're looking at
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Re: Nissan Leaf BMS

Post by johu »

Revisiting the supposedly integrated isolation monitor. Now that prensel figured out how to get the DTCs I thought it would be fairly straight forward to warn about an isolation fault.
But the only codes that exist diagnose the isolation monitor itself: P33DF (Signal voltage of the on-board isolation resistance monitoring system is too high.), P33E0 (Signal Voltage of the on-board isolation resistance monitoring system is too low.) and P33E1 (Signal voltage of the on-board isolation resistance monitoring system exhibits no amplitude variation)

So is there maybe an isolation resistance value somewhere in the 0x7BB blocks? I couldn't find one in the data that is spit out periodically.
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Re: Nissan Leaf BMS

Post by janosch »

Hi,

very interested in this. I think Dala ran experiments.

Code: Select all

- In 0x55b the LB_IRSEN is handling the insulation resistance.
Can you provoke an isolation fault with a big resistor (250M or something)? We had to do that for the safety certifications, a CAN capture with the provoked fault or however DTC are read should be easy enough to figure out.

I will have a go next time we have to do that exercise, but might not be until summer.
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Re: Nissan Leaf BMS

Post by MikeinPA »

24 kwh 2013 Leaf. I am wondering about bringing the BMS out of the battery enclosure by extending the the 6 cables going to it (I see someone has kindly located the connector part numbers needed to make extensions). Reason: I am replacing 3 weak modules with modules of higher capacity, and may want to rebalance some cells in the future. With the BMS/cables in a more accessible location, simple to disconnect the BMS and balance through the connectors. Just wondering about moving the BMS--not planning on doing this! My question is whether RF noise would create problems for the 24 kwh BMS. I can see modifying the top of the enclosure to allow routing/sealing/shielding/protecting the cables, and putting the BMS under the driver side rear seat in another shielded dry compartment. There would be some way to easily disconnect the extension cable in order to drop the battery. Just wondering really. As these cars age, there will be a lot of life left in them if people can repair packs and stay on top of any balancing non-idealness. TIA, and thanks for this forum.
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Re: Nissan Leaf BMS

Post by johu »

I've seen both. The 40 kWh BMS does not like extensions, with the 30 kWh (same BMS chips as the newer 24 kWh) I couldn't observe issues.
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Re: Nissan Leaf BMS

Post by MikeinPA »

Thanks johu.

Getting better access to the BMS could be a simple as moving it up a few inches, modifying the enclosure if needed to fit the new position, make an access cover on the enclosure, modify the vehicle body under the driver-side rear seat to accept the taller portion of the enclosure, and make an access cover there as well.

I am assuming that one would want to disconnect the BMS before sending ~ 1 amp balancing current on a pair of the balance wires to one of the cells. But if whatever one is using to get current to or from a cell is floating with respect to any ground, is that even needed? Suppose I had another loose cell and a correctly sized resistor, the balance wires were (safely) tapped, 12 volt power to the BMS was off--just connect the loose cell to raise or lower the target cell inside the enclosure while leaving the BMS connected? This is all theoretical--modifying the balance wires in the enclosure would be a major task for me in that I would have to learn how to do this safely (although I think the balance wires are intrinsically safe).

Neat forum.
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Re: Nissan Leaf BMS

Post by MikeinPA »

Three questions on how the Leaf LBC is controlling the individual shunts. Here http://www.wolftronix.com/E10_LithiumUpgrade/index.html Wolftronix identifies that " the balance shunt enable/disable control packet is 0x55 0x99 0xXX 0xFY 0xZZ " on a 2013 LBC. Question 1, is this control packet coming from the microcontroller? Meaning the shunts will only be activated when the microcontroller is powered by 12 volt and sending packets? I am assuming this is a yes, but would like to be sure. And obviously one would want the shunts off if the car is off for a long time. Question 2, is the active shunt definitely just taking current from the cell positive and returning it to the same cell's negative--bleeding off a little energy and hence a little voltage in the process? Nothing more complex like transferring the charge to another cell? I cant read the diagram well enough to understand that. Question 3, has anyone determined how the microcontroller is deciding to turn some shunts on? The last question is interesting in that I can imagine the microcontroller is looking at all 96 cell voltages, and could be doing more than just "shunt the six highest cells" or "shunt the cells that are + 5% of the pack average", or "shunt all high cells until the LBC gets too warm".

The reasoning behind the above questions is that if one could wake the LBC and leave it on for a while, it could do more balancing than what would occur during normal driving use. Normal use is probably about 500 hours per year at 10 mA for which ever shunts the LBC has decided should be on. Doing this would at least require disconnecting the 12 volt battery in the car, and powering just the LBC--technical details to be worked out but one could add a connector to the cable coming from the lithium battery where it enters the cabin, isolate the lithium battery cable, and power it with 12 volt via the battery sniffers others have designed. I have one 2013 with near perfect balance after 70k miles (just really nice flat bar graph), and another 2013 with the battery going back together currently. I had to replace three modules and it will be very well balanced when I seal it up, but I am wondering about how the three new modules will fare over time and would like some way to rebalance the pack with out all the work of getting it open again. The same technique might help others, whether the LBC is in a Leaf or or a conversion. I would love to do a Jetta Mk IV Wagon btw.
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Re: Nissan Leaf BMS

Post by johu »

yes, you can't influence balancing from outside, it simply bleeds some charge off using a resistor and the strategy looks much like top balancing. The LBC seems to remember which cells need charge bleeded off and continuously shunts the cells in question, so not just at the very moment that their voltage is above the others.

When the LBC is off, i.e. none of the enable-lines active it also stops balancing.
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Re: Nissan Leaf BMS

Post by MikeinPA »

From the Nissan EVB Technical Manual: "During cell capacity adjustment, the capacity of each cell is estimated based on the no-load voltage when the system starts, and the capacities are adjusted so that they are all at the target level. The voltage of each cell is detected inside the Li-ion battery controller. The bypass switches are then turned ON to discharge the cells that have excess capacity. In this way, capacity adjustment by the Li-ion battery controller allows the capacity of all cells to be fully utilized."

So it looks like it decides which cells to bleed from the resting voltages at startup. Although I recall someone made a comment on one off these boards that they saw the shunt status change in leaf spy.

Thanks for the response. I still have a lot of questions, but should be able to learn more once the pack is back together and I have Leaf Spy in BMS mode.
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Re: Nissan Leaf BMS

Post by Cookie6000 »

@johu, I finally have the Audi running around again on the 2015 24kWh pack (grey molex) and during some rewiring, I found 2 of the 96 voltage taps in the wrong connector position. Success! I wired up the Can, 12v feeds for the Perm, Ign and charge mode as well as reusing the Leaf current sensor in there.

Question is, and it's something I couldn't figure out reading through this thread was, the interlock - A: is it necessary and B: can it inhibit balancing in charge and discharge mode if not terminated/used
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Re: Nissan Leaf BMS

Post by johu »

Very good!
With the interlock disconnected there will be no balancing.
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Re: Nissan Leaf BMS

Post by Cookie6000 »

Brill. Thanks johu. Both interlock input/output wires are now joined.
Just waiting on the LElink BLE module to arrive. Old Veepeak odb2 reader I have won't work with Leaf Spy Pro. Once I have all that in place, it's time to plug it all in.
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Re: Nissan Leaf BMS

Post by janosch »

Cookie6000 wrote: Sun Apr 23, 2023 8:01 am ... I found 2 of the 96 voltage taps in the wrong connector position. Success! ...
viewtopic.php?t=2085

Might be just too late for you now, but I made a gizmo to help you with finding issues like that. Linking here for future readers.
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Re: Nissan Leaf BMS

Post by shuma89 »

Hello everyone.
I have 40kwh Catl battery in nissan leaf 2012 ZEO.
I bought it from china. It works very good. But my car can not count all of kwh-s.
It says that battery soh is 103% and charged battery capasity is about 22-24kwh.
Dashboard says about 180-210km distance, but car can drive about 300-320km. Whan i drive 180-210km, on dashboard there is only --- but car drives about 100km after disappearind the driving distance to "---".
What can i do to solve this problem?

I changed only batteries, not BMS or other parts in battery box.
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