AndyH
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 12:42 pm

LakeLeaf wrote:That's actually smaller then I thought. The previous primary speculation seemed to be ~30kW pack running between 10% and 90% for a usable capacity of ~24kW.

It would seem from this report that the pack may run from 5% to 95% for ~24kW of usable capacity?
A bit smaller, yes. The NREL model says we use 84% while the Nissan public comments said 80%.

84% of ultimate for 24kWh is a 28kWh pack.

It's looking like the NREL model's 84% between 95% and 11% is looking pretty accurate - and also fits better with Nissan's suggestion that 80% charges will improve pack life.

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evnow
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 12:47 pm

LakeLeaf wrote:It would seem from this report that the pack may run from 5% to 95% for ~24kW of usable capacity?
Probably more like 5% to 90%. But the bottom should be rarely touched - as one wouldn't (shouldn't) be hitting turtle mode too often.

Or it could be 10% to 95% (Perry had been quoted as using the 95% figure). You get to the 10% when you hit turtle. There was some news report of Nissan saying "yes, we have a little bit of reserve at the end".
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TomT
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 12:58 pm

Other than possibly affecting battery life over the long term, I still don't see how it makes any real-world difference. The only number that matters to end users is the usable capacity. It could be 50Kw total capacity, for example, but if you can only access 24Kw of it, it still would make no real difference to most of them.
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AndyH
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:00 pm

evnow wrote:
LakeLeaf wrote:It would seem from this report that the pack may run from 5% to 95% for ~24kW of usable capacity?
Probably more like 5% to 90%. But the bottom should be rarely touched - as one wouldn't (shouldn't) be hitting turtle mode too often.

Or it could be 10% to 95% (Perry had been quoted as using the 95% figure). You get to the 10% when you hit turtle. There was some news report of Nissan saying "yes, we have a little bit of reserve at the end".
Yes - there's reserve at the end, but that's inside the 24kWh user zone.

For total capacity, based on this new info, the NREL model, and the service manual's BMS voltage limits, it's looking like user 100% is ultimate 95% (up from the earlier 90% estimate).

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EVDRIVER
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:03 pm

That 27kwh calculation is based on the ah rating listed in the system times voltage so it is somewhat variable.

AndyH
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:06 pm

mogur wrote:Other than possibly affecting battery life over the long term, I still don't see how it makes any real-world difference. The only number that matters to end users is the usable capacity. It could be 50Kw total capacity, for example, but if you can only access 24Kw of it, it still would make no real difference to most of them.
You're correct if one is focused only on user available range.

Total capacity is the number we need to calculate the C rate for charge and discharge. This lets us look at how hard the pack is working and how much heat (isn't!) generated during high-speed driving and fast charging. And yes - gives us another way to confirm/deny pack capacity at the 8-year warranty mark.

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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:10 pm

This is great news because it reassures us that the pack will be long lived, if you only charge up to 80% of usable then even better, the car will rust to death before the battery fails. Can you now access actual cell temperatures during use?.. should be handy to decipher the CAN bus.

Any ideas on the actual energy density of the cells with this new data?

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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:31 pm

Herm wrote:This is great news because it reassures us that the pack will be long lived, if you only charge up to 80% of usable then even better, the car will rust to death before the battery fails. Can you now access actual cell temperatures during use?.. should be handy to decipher the CAN bus.

Any ideas on the actual energy density of the cells with this new data?
The module weight is on the AESC website (3.8kg). It appears that AESC's 66Ah number on their site is the consumer capacity rather than ultimate. This is common for battery vendors, but not universal, so it's good to have confirmation.

http://www.eco-aesc-lb.com/en/bmodule.html

Reserving 10% top and bottom gives the best capacity/life ratio - so routine charges to 95% should put us into 150,000 mile pack life territory...

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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:34 pm

Yaaaaaay!! Finally, an answer. Thanks EVD.

IBELEAF
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Re: Actual LEAF Pack Capacity

Wed Feb 23, 2011 1:38 pm

Herm wrote:This is great news because it reassures us that the pack will be long lived, if you only charge up to 80% of usable then even better, the car will rust to death before the battery fails. Can you now access actual cell temperatures during use?.. should be handy to decipher the CAN bus.

Any ideas on the actual energy density of the cells with this new data?
Why would 80% charge be any beneficial? I see this discovery as there is no point to charge to 80%.
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