Battery upgrade, charging ok, but time to time got "power limitation"

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Toucouleur

Member
Joined
Mar 27, 2019
Messages
11
I guess my main issue is cell balancing is not done, as the full charge set the battery level to 94 or 95% (it's a brand new battery with CATL module of 53kWh)

Is there a way to force the battery balancing as I think there is a slight voltage issue on the cell #89 and it will be solve only with the balancing

I'm not sure that's the reason why sometime I have the message "Power is limited". Sometime if I stop and start again the car the message is leaving but it's really random issue.

Thanks for any advice
 

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You either have a balancing wire loose, or the cell is actually 200mV lower than the rest. The LEAF BMS has an extremely weak balancing resistor, that can only bleed off a few mA at most. Getting that 200mV imbalance sorted naturally will take between 6-12months of keeping the vehicle constantly ON.

Open the battery, inspect the wiring / cell. When you build custom packs (or really check any pack), it is best practice to test the BMS in standalone mode before sealing it up and installing it onto a car. I have instructions here on how to check that all 96 cells are OK before you commit to installing the battery: https://github.com/dalathegreat/Nissan-Leaf-Battery-to-OBD2

Sorry to be the bearer of inconvenient news, time for rework!
 
I'm not sure that's the reason why sometime I have the message "Power is limited".
Once you address Dala's points (and you may just have a "bad" cell/module), I think you should address the Power is limited message for other (potential) users of this brand. It's possible these Chinese cells aren't "up to" (for lack of a better term) the power requirements of the Leaf, as certain acceleration (and even environmental) scenarios have high-current requirements. Just sayin'.
 
I attached the latest screenshot I took from LeafSpy today

The SOH value keeps increasing, and it's probably a good news news. When the battery was just changed BMS was used to give me around 67% of SOH now It reaches over 90%.

After being fully charged, the car starts without any problems. But if I drive only 20 kilometers and turn the car off and start again the again, I got again the "Power engine is limlited". This is a real problem for my work.

Can LeafSpy allow this limit to be removed using DCS message? If so how ?
 

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You have a consistent 196 mv difference from max to min, that is WAY too much difference. Until you address that issue, there is no point talking about anything else.
Normal variance is around 20 mv and up to 50 mv will be acceptable 196 is not.
When the BMS 'sees" that, and it may grow while under load, it will restrict power to prevent damage.

As Dala pointed out, the only way is to open the pack and either manually bring that cell up, or replace that cell if it can not be brought up to the rest.

You must go back into the pack or replace the whole pack with a better balanced one.

There is no external way to correct this problem, and until you address it, there is no point doing anything further.
You may or may not be able to cancel it with Leafspy, but it will just return, until the conditions are changed it will keep coming back.
When you put a load on the pack, that low cell will dip below a threshold and the reduced power warning will be triggered. When at rest it may be just above the threshold and you can clear the code, but as soon as you load it, the condition will be right back.
There is no "cheap easy" way out.
 
I can't easily remove the pack. If I could I would already did it, I'm not a professional, just a normal guy, without a reliable company to deal with close to my location, and since I put this new pack in the car and started to use it, I need to find a way to fix this.

I still don't understand why the BMS can't balance the remaining 200mV. Before upgrading the difference was even worst (or I think that might be worse I'm not sure to remember exactly), but 200mV should not be a big deal for any BMS so why after few charge it can't handle it?

I'm always charging with domestic charger (2,4kWh or 4kWh) would it change anything considering the BMS if I try to charge with a quick charger (I mean over 25kWh or more?)


I understand clearly your answers regarding the bad module, weak ceil but guess I can't do anything about it for now. I'm not reach either and can't invest to ship the car to Finland to make it work sadly.
 
To the best of my understanding, the Bms can only put a small resistance across the “high” cells to bring them down to the lower cell level.
As Dala said, it would take 2 years to draw down the rest of the pack to that one cell’s level.
I know what it like to wish, hope, and pray for an easier way out. It has taught me the harsh reality that it is better to face what the data is telling you head on the keep trying to make it something it isn’t.
It sounds like you, or someone you paid had the pack out and open at some point in the recent past. Either go back to them or open it yourself and deal with the problem, or cut your losses and move on.
I know it sounds harsh, but electrical/mechanical stuff doesn’t care how difficult it is to make the repair.
 
Make a laefspy capture of the cell voltage graph when the pack has been drained down to the lower level such that the Low power warning comes On--then you will see that the 196mV has likely grown to a much greater level, plus you can see how low that cell actually is getting. Doesn't fix anything but provides data.

The balancing bleed current in the LBC is only about 10mA max and really useless for such a large difference.
 
I attached the latest screenshot I took from LeafSpy today

The SOH value keeps increasing, and it's probably a good news news. When the battery was just changed BMS was used to give me around 67% of SOH now It reaches over 90%.

After being fully charged, the car starts without any problems. But if I drive only 20 kilometers and turn the car off and start again the again, I got again the "Power engine is limlited". This is a real problem for my work.

Can LeafSpy allow this limit to be removed using DCS message? If so how ?
if you a so unbalanced cell for a new pack, you can have more issue too, please enable leafspy log, put leafspy enhorizontal en grab a video during heavy load or long accelerations, then share all here. This could give a good idea of the issue of the cells that could be more respect the flaky cell.
Out of curiosity how's the provider of the kit? Vivne, Yaste, AUG, CVC, someone else?
 
This is what it looks like at Full Throttle for about 1000m and then release and using the generative brake. The battery should be a 53kWh battery not a 40kWh but as we can't set 53kWh on LeafSpy I keep it like that. Note that video was recorded about 10 minutes after I cleared the DTC HV Battery to let me use the car without the limit of power.

The battery comes from AUG : -https://augbattery.en.alibaba.com/
 

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Make the scan when the SOC is down below 50% to see how large the voltage difference grows. Catch it at WOT to see what is happening.
 
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