Which battery is better?

[dafrizz]

Hi, I'm trying to decide which used Leaf to buy and am interested in people's opinions on the two different batteries.

One is 24 kWh, the other 30 kWh. Leaf Spy is telling me that one has slightly better health and is a tiny bit better balanced, the other one has a slightly higher voltage per cell. What I find interesting is that one has done 18,000 km, the other one 62,000 km, so quite a difference in number of charges but similar health.

[LeftieBiker]

Are you aware of the issues with the 30kwh battery? If not, please read the buying guide that I will link shortly. If you are, then IF the 30kwh pack has had the BMS update, and IF it was a while ago, then you'd get significantly more range with the 30kwh Leaf, and would also have a substantially longer battery degradation warranty.

http://www.mynissanleaf.com/viewtopic.php?p=538030

[dafrizz]

Thank you. No, I was not aware of those issues.

I should probably also mention that I'm in Australia and am pretty sure that warranty here is different (possibly non-existent if it's a grey import).

The 30 kWh (2016 model) car is showing 174 km at full charge if that helps.

[LeftieBiker]

We don't actually know if the Japanese or EU 30kwh batteries have the same issues, so that complicates your decision. Posting your LeafSpy info here, especially the cell histogram, may help us to help you.

[dafrizz]

What I posted above is all the leafspy info I have unfortunately.

[alozzy]

The 30 kWh (2016 model) car is showing 174 km at full charge if that helps.

The 174 km range the car shows isn't useful for making a buying decision - it's mocked as the guess-o-meter (GOM) for a reason.

You can use LeafSpy Pro to obtain the BMS firmware version, there's more than one thread on that in these forums.

Do a Google search:

"BMS firmware" "30 kwh" site:mynissanleaf.com

[LeftieBiker]

<Slaps forehead> Never mind - that was what I meant. I was doing two things at once when I wrote that. The battery looks fine. Even in North America, where the 30kwh battery made here has proven problematic, there are plenty of good ones. It's the only battery that Nissan made that ranges in quality and longevity from as bad as the original "Canary" pack, to equivalent to the well-liked "Lizard" pack.

Alozzy slipped in ahead of me. IIRC, there is no firmware update for 30kwh batteries made in the EU or Japan.

[Stanton]

They both look OK, but I would rather see the cell graphs at a lower SoC (like <<50%).
Having said that, beware of 30 kWh packs (as already mentioned). Notice the 30 kWh pack doesn't have near the miles on it as the 24 kWh...yet the health readings are similar.

[SageBrush]

I should probably also mention that I'm in Australia and am pretty sure that warranty here is different (possibly non-existent if it's a grey import).

That is a very important point to clarify.

But beyond that,
So long as a LEAF has not been in a wreck or has obvious problems/damages/defects, it is all about the battery pack health (SOH) and pack capacity. You can ignore the odometer. In the USA the 30 kWh packs had calibration issues that lead to incorrect LEAFSpy readings. I don't know if the same is in play for the car you are considering so my advice would be to do a charging test to verify pack capacity.

Charging test:
Find an EVSE that you know the Power.
Start (and note) the charge at a SoC below 30%

Energy into pack will be Power * time * 0.88 = E

Note ending SoC (anything below 95% is fine). Shoot for a SoC increase of around 50%
Calculate SoC increase

Total usable capacity is E / (SoC_increase)

[LeftieBiker]

In the USA the 30 kWh packs had calibration issues that lead to incorrect LEAFSpy readings.

This was Nissan's explanation for the issues with the 30kwh pack, and it appears that a few of the cars did have that problem. However, Nissan wouldn't have had to replace so many 30kwh batteries if "calibration issues" were the entire problem. It is quite clear at this point that many of those batteries have some sort of defect that wasn't caught by Nissan. My suggestion remains to make sure that the car you want to buy has had the BMS update at least a few months ago, and that it still has good LeafSpy readings that are not dropping noticeably.