Poor regeneration while braking.

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cooperplace

Member
Joined
Jul 29, 2022
Messages
7
Since replacing the 12v battery in my 2012 Leaf the regen braking has been poor. Before the new battery, on braking the regen dots would go to 5, all the way to the left, and would respond to using the brake pedal, but no more. Now on taking my foot off the accelerator it will go to 2 or 3 regen dots and no more. Braking has no affect. This is in normal or econ mode. Happens on 80% charge (I never got to 100%) or much lower. Not related to temperature. I tried disconnecting/reconnecting 12v battery but no effect. Does regen braking rely on a fuse?

Any advice much appreciated.
 
What's the state of health (SOH) of your pack via LeafSpy? As the pack degrades, you get less regen.

Definitely odd though that the regen is suddenly diminished after replacing the 12V battery. Doesn't make sense.

Does LeafSpy report any trouble codes?
 
Battery has 11 bars on the dash. Don't have L/spy. Am open to recommendations for a OBD2 reader and software. Bought several for a previous car and didn't like any.
 
A 2012 showing 11 bars SOH/Capacity, or 11 bars charged/SOC? (There are 2 sets of bars, Inner and Outer)

If SOC, then regen would be diminished due to the "high" voltage state of the pack and the regen power will only show 1 or 2 single bubbles on the gauge. As you drive the car and the SOC goes down, then the regen bubblers will increase and even show the doubles.

If SOH, then either you have a new pack or someone has reset the VCM. No way a 10 year old pack would be that high.
 
Okay that explains the 11 SOH bars, that's great that you have a fresh pack.

i use an OBDLink LX to talk over bluetooth to my Android phone device; they also make an MX version that uses wifi for iphone but i have no experience with that one. It uses the STN11xx chip set rather than the ELM chip and seems to be superior performance. Buy it direct from the manufacturer scantool.net, there are many cheap clones and counterfeits out there.

Temperature is another big factor to consider in regeneration braking. But maybe you will find some DTCs with laefspy that will give some clues to why it changed after 12V swap.
 
Iirc, there was a firmware upgrade for some of the earlier cars that down-rated the regen in an attempt to preserve the battery. Is it possible the firmware was applied but never took effect until the 12V power reset?
 
nlspace said:
Okay that explains the 11 SOH bars, that's great that you have a fresh pack.

i use an OBDLink LX to talk over bluetooth to my Android phone device; they also make an MX version that uses wifi for iphone but i have no experience with that one. It uses the STN11xx chip set rather than the ELM chip and seems to be superior performance. Buy it direct from the manufacturer scantool.net, there are many cheap clones and counterfeits out there.

Temperature is another big factor to consider in regeneration braking. But maybe you will find some DTCs with laefspy that will give some clues to why it changed after 12V swap.

Thanks, but not related to temperature.
 
cooperplace said:
The 11 bars is SOH. It got a new battery from Nissan about 2.5 years ago.
You might be in the same boat as me. I drive a 2012 that had a warranty replacement battery in 2019. For 2 years, it was like a new car: 12 bars SOH, good and predictable range, always full regen. Then last year it started going wild on the GOM: it would drop 10 km expected range in 2 km of driving. Real range dropped from over 100 km to about 76 km. There are no weak cells according to Leaf Spy, just generally high internal resistance. It's still showing 11 SOH bars, but I think it behaves like an 8 or 9 bar.

My suspicion is that the 24 kWh battery's cells are no longer made, so Nissan are using cells from stock, and they have considerable calendar age on them. So the warranty replacement battery isn't new, just unused. Nissan didn't promise new, just better than 8 bars SOH.

But with the coincidence of the auxiliary battery being replaced, I think it's worth your charging it really well; "new" batteries from a shop don't necessarily have a great SOC, and 2012s in particular don't charge the auxiliary battery well. It's also possible though unlikely that you have developed one or a few weak cells that are holding back the whole pack. The VGate OBD dongles seem to have reasonable performance and cost. You can possibly use the free version of LeafSpy to get an idea of what's going on, but the for-money version isn't all that expensive. LeafSpy is definitely the app that you want, IMHO.
 
Ok thanks. Yes I made sure the auxiliary battery is fully charged. I bought a Konnwei OBD2 dongle and installed Leafspy Pro on my phone. The braking graph just shows zero, no graph at all.

How should I look for error messages?
 
cooperplace said:
Ok thanks. Yes I made sure the auxiliary battery is fully charged. I bought a Konnwei OBD2 dongle and installed Leafspy Pro on my phone. The braking graph just shows zero, no graph at all.

How should I look for error messages?

The service functions are disabled each time LEAFSpy Pro exits.

To enable:
Choose Settings (Three horizontal lines , sometimes called Hamburger, at top right of screen)
Click Gear Icon Settings on pop-up menu.
Service Screen Enable Option is fourth group from the top.
Check Enable and restart LEAFSpy Pro.

As noted in the LEAFSpy Pro Help, do NOT clear Diagnostic Test Codes until you have recorded them and know their cause.

Once cleared there is no way to get them back other than waiting for them to happen again.

If you end up using a dealer, they won't be there for the dealer to read with the Consult and do troubleshooting.

I have not experienced your loss of regenerative braking with a 12V battery replacement.

It is possible the new 12V is bad. I have destroyed two or three 12V batteries in the 2011 LEAF. When they go bad, they might have just enough voltage to start the LEAF, but the minute the 12V buss is loaded heavily like starting the AC as someone stated in another thread, the 12V voltage may plummet to less than 10V. (Have been doing good with Optima 51R Yellowtop AGM since August 2019)

A 2011 LEAF braking is extremely erratic when attempting to work with low 12V buss voltage. Been there once or twice with nearly failed 12V. The braking can be downright dangerous.

But coulomb's theory could be correct and your main pack resistance may have reached a threshold to disable regeneration.

My main pack is Nissan warranty replacement installed six years ago August 2016. I have lost only the first capacity bar so far. But SOH is down to ~80% and Hx which is thought to be pack conductance is ~60%.
If coulomb theory is right, I might lose regenerative braking soon.

What is your SOH and Hx?
 
Hi Tim,

Thanks. The new 12v battery is fine. SOH is 11 bars. Acc to Leafspy, Hx is 66.25%.

What's Hx?

I don't think this issue is related to main battery SOH. The car had great regen braking until a new 12v battery was fitted, and then v little.
 
cooperplace said:
The new 12v battery is fine.
What are you basing that on? If it's just because it's new and you charged it, it could still be faulty. If it's because is shows say 13.8V when you boot it to ready mode, that means nothing. It could be weak as a kitten, propped up by the DC-DC pouring in whatever current it takes to get to that voltage (up to ~150 A).

SOH is 11 bars. Acc to Leafspy, Hx is 66.25%.
Not too far from mine. Mine is just over 3 years since the warranty replacement main pack, 11 SoH bars, SoH 81.14%, Hx 62.88% (last time I ran LeafSpy, which is several weeks ago).

What's Hx?
No-one knows for sure, but experienced drivers have noticed a definite inverse correlation with internal resistance of the main battery. When this is higher (i.e. Hx is lower), the voltage sags more under load, and rises more under regen. If one of the cells goes over-voltage, the firmware cuts you back another regen bubble to prevent that cell from over-voltaging. If a cell goes under-voltage, you will lose a power bubble. I've not noticed losing a power bubble yet, but I regularly lose 2-3 regen bubbles after charging to 80%. They come back after losing one or two SoC bars.
 
cooperplace said:
My regen braking does not come back when the SOC drops.
Do you get any variation in the number of "single circles"? For example, here is my 2012's dash soon after charging to 80%; usually I lose two bubbles, but today it's just one. I had to go to ready mode (not just "on" with two presses of the start button and no foot on brake) so see this.

OXNqscz.jpg


Edit: in case you think that range is brilliant for 80% SoC, remember that it's km (107 km = 66.5 mi). And the estimated range falls like a rock over the first few minutes of driving. I've since realised that this is mainly due to my quite low Hx (under 63%, indicating high internal resistance). I recently ran it down to VLB warning, and the estimated range goes much slower towards the end, even increasing a tiny bit with very light regen. The firmware calculating the estimated remaining range doesn't seem to expect Hx to be so low for a battery that still has enough State of Health to warrant 11 health bars.
 
I'm not experiencing poor regen yet, but when I do I will buy one of Dala's CANBUS bridges as his custom firmware restores original regen levels, in addition to a bunch of others nice features.

https://dalasevrepair.fi/can-bridges/
 
alozzy said:
I'm not experiencing poor regen yet, but when I do I will buy one of Dala's CANBUS bridges as his custom firmware restores original regen levels...
I don't know exactly how that feature of Dala's CAN firmware works, but my guess is that it overcomes a temporary tendency of the factory firmware to deny regen on the replacement pack because it hasn't yet learned that the battery is suddenly much better than historic data indicates.

Allowing 100% regen all the time would cause cells to over-voltage and deteriorate even faster than they already are. They may also swell and I think that there is a chance of failure or even fire. I'm sure that Dala is aware of that, so I doubt that you'd get much if any benefit from this particular feature applied to an aging pack.

But perhaps there is some other problem with factory firmware that I've never heard of but @Dala knows, which denies legitimate regen and he can safely work around.
 
My guess is that Dala's system watches the BMS, generally allowing one or two regen bursts in a given time frame, and beyond that, depending on cell temp and voltage. Older, depleted packs have less of a problem finding "room" for more charge after the first couple of miles.
 
At some point, usability and range will be more important to me than longevity. A 9 bar LEAF is on borrowed time anyways, so why not exploit as much range and usability even if it means higher degradation...
 
If I may, following this thread, it was mentioned that swapping out with a new 12v battery might re-set some things. Along those lines, (I'm a new leaf owner btw, a new EV owner all together for that matter) If/when I need to replace my 12V battery, what steps, in what order should I perform that task. Right way / wrong way/ best practices etc.. Or point me to a good source that explains it in detail?
thanks
 
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