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Marktm
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Delivery Date: 09 Jan 2016
Leaf Number: 022737

Replacement Battery with low cell Voltages

Sun Jan 08, 2017 11:26 am

Battery was replaced in early November (under warranty) and has already lost about 3% (varies) amp-hours and HX. What is concerning is the last quadrant of cells (73-96) consistently have the lowest voltages. Attached is the near-depleted voltage ranges. I understand this "magnifies" the deltas, but over 110 mv?? Normally at full charge the delta is 20-30 mv.

Should I question Nissan about a "bad" replacement - mainly to get the "problem" on record? - or is this to be expected?

IMG_4859.PNG
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2012 Leaf SL; 34,000 miles. 12 bars - Battery replaced November 1st, 2016.
4000 watts Grid-tied solar. 3000 watts (level II) off-grid solar Leaf charging capable.

2011RedLeaf
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Joined: Tue Jan 03, 2017 8:49 pm
Delivery Date: 10 Oct 2012
Leaf Number: 3999

Re: Replacement Battery with low cell Voltages

Sun Jan 08, 2017 5:41 pm

What have you got to lose by bringing it to their attention. At the least, you would get peace of mind.

sendler2112
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Joined: Wed Jan 06, 2016 5:05 pm
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Location: Syracuse, NY USA

Re: Replacement Battery with low cell Voltages

Sun Jan 08, 2017 7:13 pm

They usually don't want to know anything about Leafspy screenshots. Only if a MIL light comes on. What does it look like at the top of a full charge after a 100% disconnect?

arnis
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Joined: Sat Jan 23, 2016 3:21 pm
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Leaf Number: 015896
Location: Estonia, Europe

Re: Replacement Battery with low cell Voltages

Sun Jan 08, 2017 8:48 pm

Looks normal. You have to have dozens of deep cycles.
Set your charge limit to 100% for a month. Go at least down to 20%.
It will level out with weeks.
Also your SOH and Hx will fall rapidly down to level it was before cells failed.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

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Marktm
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Joined: Thu Jan 21, 2016 10:49 am
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Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 7:22 am

sendler2112 wrote: What does it look like at the top of a full charge after a 100% disconnect?

This is the profile at 278 GIDs. The new battery has had at least a half dozen "full" charges with several taken to VLBW - all level 2. The same cells (73-9) have always determined the max delta mv.

IMG_4835.PNG
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2012 Leaf SL; 34,000 miles. 12 bars - Battery replaced November 1st, 2016.
4000 watts Grid-tied solar. 3000 watts (level II) off-grid solar Leaf charging capable.

arnis
Posts: 700
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
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Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 8:42 am

Ok. You have to continue cycling the battery.
Interesting, that cells that are new are at lower voltage AND are shunted to discharge.
That doesn't make sense. Every other cell should be red, and those low voltage cells blue.

Just for a test run it down to turtle, aka 0.5kWh left. Make some screenshots.
Be near the home. After running down to 0,6 go home and run heater at max.
Take some screenshots. Leaf will die. Then make another screenshots and start L2 charge
immediately.
I would recommend doing it when battery is below 7 temperature bars.
Also battery must be at least 15C (all sensors) aka 59F converted. (otherwise Hx SOH update will not happen)
Charge to 100%.

Leaf should die when one of the cellpairs falls down to 2.6V.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

sendler2112
Posts: 213
Joined: Wed Jan 06, 2016 5:05 pm
Delivery Date: 07 Jan 2016
Location: Syracuse, NY USA

Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 8:57 am

What does running it so low do besides amplifying the screenshot of any cell mismatching?

arnis
Posts: 700
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 9:41 am

It might force BMS to balance harder/faster.
BMS only sees cellpair voltages. It takes that data to balance them.

Do not baby the battery. I hope you already noticed that doesn't help.

Voltage delta should get smaller over weeks. Also if new cells are more degraded
then they will be depleted earlier. Therefore pack will never get balanced.
If new cells are in better health all other cells will run out of juice earlier.

My battery is in very good health. Voltage delta at full charge is less than 10mV.
When pack is really empty delta is as high as 400mV.

https://goo.gl/photos/xxzQQZgzxPtXbxPV9
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

sendler2112
Posts: 213
Joined: Wed Jan 06, 2016 5:05 pm
Delivery Date: 07 Jan 2016
Location: Syracuse, NY USA

Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 11:31 am

The packs only balance when the highest cells are shunting at the top while the charge is still connected. Constantly taking the pack to the very bottom will just take the imbalance to the maximum. This is a warranty replacement pack that Nissan just put in for free. They are not going to do anything else for this car unless a MIL light pops on.

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Marktm
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Joined: Thu Jan 21, 2016 10:49 am
Delivery Date: 09 Jan 2016
Leaf Number: 022737

Re: Replacement Battery with low cell Voltages

Mon Jan 09, 2017 11:33 am

arnis wrote:My battery is in very good health. Voltage delta at full charge is less than 10mV.
When pack is really empty delta is as high as 400mV.


Seems very high delta mv, but obviously it is highly variable with the SOC of the battery. Is there an "alarm" point of delta mv that will set an error code in the system - and does it take the SOC into consideration?
2012 Leaf SL; 34,000 miles. 12 bars - Battery replaced November 1st, 2016.
4000 watts Grid-tied solar. 3000 watts (level II) off-grid solar Leaf charging capable.

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