jbanyer
EV Enthusiast
Posts: 15
LEAF OWNER?: Yes
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Post by jbanyer on Jun 11, 2018 23:21:24 GMT 11
I just bought a 2012 LEAF a few weeks ago, and started using Leaf Spy Pro about 2 weeks ago. The car shows 9 battery health bars. In the last 2 weeks, according to Leaf Spy the SOH has dropped 1% per week. This can't be true right? At that rate, the battery would lose 50% SOH per year! The car is 5 years old and was at 75% SOH two weeks ago, suggesting that 5% loss per year has occurred. Is this just a measurement thing? I tried running the battery down to 5% SOC then charging to 100%, but it didn't increase the SOH. The ambient temperature has not changed much over the last two weeks. Leaf Spy Log attached and excerpt below. Date AHr SOH 05/30/2018 49.331 75.20% 05/30/2018 49.272 75.11% 05/31/2018 49.22 75.03% 05/31/2018 49.174 74.96% 05/31/2018 49.003 74.70% 05/31/2018 49.003 74.70% 05/31/2018 49.003 74.70% 06/01/2018 48.879 74.51% 06/04/2018 48.682 74.21% 06/07/2018 48.262 73.57% 06/09/2018 48.065 73.27% 06/09/2018 48.058 73.26% 06/09/2018 48.026 73.21% 06/09/2018 48.013 73.19% 06/11/2018 47.921 73.05% 06/11/2018 47.921 73.05%
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Post by Feng on Jun 11, 2018 23:34:18 GMT 11
Could it be a bad cell? Does the graph in LEAFSpy show any cell unusually lower or dropping faster than the rest when it discharges?
Do you know when the LEAF was first sold and is it under 100,000km? If you're lucky you could qualify for a replacement battery.
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Post by rusdy on Jun 12, 2018 14:45:47 GMT 11
Hi jbanyer, That is definitely not normal, considering it was at 75% already when you got it. Have you ever monitor your cell voltages during normal driving? You want to look for a weak cell (hopefully not cells). If you haven't done so, my suggestion: - Drive it until it's low charge with your LeafSpy active at all times, not too far from your place (so you can come back quickly if things go wrong);
- Set your LeafSpy at the battery cells voltage page. Monitor the growing gap of cell voltages (normally, no more then 25mV between lowest and highest cell);
- As the battery SoC depletes, the gap voltage (between lowest and highest cell) increases. The gap will drastically increase from 50-ish mV to 200-ish mV from my own experience. You want to note when this happens (at what SoC);
- Normally, this happens at low charge (beyond Very Low Battery Warning, i.e. VLBW). At this stage, your GoM (Guess-o-meter) already showing '***'.
Some brave souls (in US) tested all the way to turtle mode and came until full stop, and his gap is merely 100-ish mV at turtle. Definitely near new condition (which is not ours). Also, I've noted that the Ah estimation (therefore, health), did some 'learning' during first couple of months usage. My theory, this was because the previous owner of mine didn't do much kms, unlike me. Note the nose-dive and then climbing up again in my data below. However, this doesn't seem applicable to you (which already at 75%). PS: Ignore the spike, my guess that was due to dealer software update.
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Post by stewartm on Jun 20, 2018 6:02:21 GMT 11
My suggestion is winter cold, temperature drop will show less capacity, it will then pick up as it warms up. It is very obvious in my French leaf as winter removes about 20% capacity with using no heating etc, just the colder temps.
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jbanyer
EV Enthusiast
Posts: 15
LEAF OWNER?: Yes
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Post by jbanyer on Oct 30, 2018 21:28:27 GMT 11
An update on this. I started this thread because the reported SOH was falling by 1% per week when I first got the car. Now I've had it for 5 months the SOH is levelling out: I wonder what's happening? Perhaps my charging / driving habits are different to the previous owner and the BMS is adjusting? I know the previous owner typically charged it to 100% whereas I mostly use the 80% charge limit. Also, the car was serviced just before I bought it. Perhaps they changed something and the BMS had to recalibrate? The car still shows 9 battery health bars, same as when I bought it. Must be close to dropping the 9th bar now? Unfortunately the 5 year warranty expired in July 2018. At least it's not plummeting down any more! Will be interesting to see what happens over a full year.
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Post by Feng on Oct 31, 2018 9:43:57 GMT 11
That's weird! Did the previous owner live in a colder climate and are you somewhere warm? It might have acclimatised over the first few weeks. That's just a guess.
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Post by rusdy on Oct 31, 2018 12:29:11 GMT 11
... I wonder what's happening? Perhaps my charging / driving habits are different to the previous owner and the BMS is adjusting? I know the previous owner typically charged it to 100% whereas I mostly use the 80% charge limit. Also, the car was serviced just before I bought it. Perhaps they changed something and the BMS had to recalibrate? My guess would be the difference in driving habit. Mine exhibited same symptom like yours (though not as severe). Graph in my previous post above. Unlikely the service would've done anything special. I gave up servicing mine for a while now (just did the major one last time on 50kk such as brake flush). Purely my opinion, minor service is pure waste of money (battery checks, yawn ). Now at almost 70kk.
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jbanyer
EV Enthusiast
Posts: 15
LEAF OWNER?: Yes
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Post by jbanyer on Oct 31, 2018 22:22:41 GMT 11
The service was done by a Nissan dealer. They also replaced the telematics unit (upgrade to 3G). There wasn't any other recall item on the service invoice.
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