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gbarry42
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 2:35 am

With regard to splitting the CAN bus, the attribute of note is whether the device(s) just listen to the bus or whether they issue commands to get their information. I believe Gary's original meter is in the former group, and I can't speak for the others, but its likely most of them issue commands, since that's how a lot of the info is obtained. Especially where it asks one controller to go get data from another (in English: asking the car controller to get info off the EV controller and so on). Readers that issue commands can have collisions if there's more than one operating.

[Edit, based on Stoaty's subsequent message with a link to the relevant thread--the more conventional term for "command issuers" is "Active Devices". As in, you shouldn't attach two active devices to the bus. Especially if they are going to ask for the same data.]

As for the low cells, it would be instructive to note which cells are the offender, and whether its the same ones each time. It isn't really the 68 mV difference that's a factor; it's really the low cell compared to the average. After all, having a few "hot" cells doesn't really contribute to your expected range. But even so, the "penalty", so to speak, is that if one cell is 68 mV low then we have to pretend they all are. 96 times that is 6.6 volts. As usual, I can't find the chart that would show how much earlier you'd run out of battery if it were 6V low.
Last edited by gbarry42 on Fri Nov 15, 2013 1:03 pm, edited 1 time in total.
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

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DNAinaGoodWay
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 2:58 am

So, it has to stay plugged in after 100% is reached to optimally balance, and for at least four hours?

Why is that? Does it draw small amounts of power occasionally during this process? I've never noticed it draw anything after 100%, but then, haven't ever looked for it.

Like most of the general public, I don't have any extra meters (although if there was a LEAF Spy for the iPhone I would), and I don't think there's anything on balancing in the manual, but maybe there should be.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

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RegGuheert
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 3:22 am

DNAinaGoodWay wrote:So, it has to stay plugged in after 100% is reached to optimally balance, and for at least four hours?

Why is that?
When the battery sits without charging or discharging, the cells should eventually get to about the same temperature. That allows for optimum balancing.
DNAinaGoodWay wrote:Does it draw small amounts of power occasionally during this process?
Yes, it will sometimes charge a little bit after the battery has gotten into an isothermal condition to fully balance the pack.

To OP: I find that running the climate control for an hour or so after the end of the L2 charge seems to bring all the cells up to their maximum voltage (4.1V) so that I have the best range for a trip. This works best when it is cold and the heater runs, which is typically when I need the boost. It's inefficient, but sometimes I can get an extra few miles this way.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

cwerdna
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 3:26 am

DNAinaGoodWay wrote:Why is that? Does it draw small amounts of power occasionally during this process? I've never noticed it draw anything after 100%, but then, haven't ever looked for it.
I've seen it draw power after "100%". Once the Chargepoint EVSE communications got fixed at my work, I am able to reliably see the power consumption graph but it's only at 5 minute intervals. Basically, when charging to 100%, once the draw drops to 0 kW, I've noticed that it periodically pulls some power, maybe ~0.4 to ~0.8 kW. It eventually seems to completely stop.

I don't think I've left it plugged in for 4 hours at 100% w/any sort of monitoring though.

The % SoC on the '13s also can have a jump/"mysterious move" (those who were present at the SF BayLeafs meeting in December 2011 will recall a "mysterious move" slide). I can be charging to 100% but there's still some time remaining, the power draw has ramped down a lot (but not 0 kW yet) and the % SoC (part of the b/w dash display) reads 98%. When I unplug and power cycle the car, % SoC often jumps to 100%.

'19 Bolt Premier
'13 Leaf SV w/premium package (owned)
'13 Leaf SV w/QC + LED & premium packages (lease over, car returned)

Please don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

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DNAinaGoodWay
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 4:25 am

RegGuheert wrote:When the battery sits without charging or discharging, the cells should eventually get to about the same temperature. That allows for optimum balancing.
So, first it equalizes temperature, then the cell voltages equalize?

When I can get off this phone and to a desktop, I'll search old threads, I remember Gary Gid writing that most of the balancing is done in like 45 minutes or so. So maybe 2 hours is enough?

But then, Tony's range test would start with a car balancing for six hours iirc, maybe he should try your cc trick.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

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DNAinaGoodWay
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 4:28 am

cwerdna wrote:
DNAinaGoodWay wrote:Why is that? Does it draw small amounts of power occasionally during this process? I've never noticed it draw anything after 100%, but then, haven't ever looked for it.
I've seen it draw power after "100%". Once the Chargepoint EVSE communications got fixed at my work, I am able to reliably see the power consumption graph but it's only at 5 minute intervals. Basically, when charging to 100%, once the draw drops to 0 kW, I've noticed that it periodically pulls some power, maybe ~0.4 to ~0.8 kW. It eventually seems to completely stop.

I don't think I've left it plugged in for 4 hours at 100% w/any sort of monitoring though.

The % SoC on the '13s also can have a jump/"mysterious move" (those who were present at the SF BayLeafs meeting in December 2011 will recall a "mysterious move" slide). I can be charging to 100% but there's still some time remaining, the power draw has ramped down a lot (but not 0 kW yet) and the % SoC (part of the b/w dash display) reads 98%. When I unplug and power cycle the car, % SoC often jumps to 100%.
I'm on a ChargePoint right now at work for 8.5 hours. Started at one bar, should take ~5 hours to 100%, I'll check to see what it draws after that.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

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DNAinaGoodWay
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 12:22 pm

Was plugged in almost 3 hours after it hit 100%.

Never drew another Wh.

Must've been balanced already.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

Stoaty
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 12:47 pm

gbarry42 wrote:With regard to splitting the CAN bus, the attribute of note is whether the device(s) just listen to the bus or whether they issue commands to get their information. I believe Gary's original meter is in the former group, and I can't speak for the others, but its likely most of them issue commands, since that's how a lot of the info is obtained. Especially where it asks one controller to go get data from another (in English: asking the car controller to get info off the EV controller and so on). Readers that issue commands can have collisions if there's more than one operating.
LeafDD and Leaf Spy don't mix:

http://www.mynissanleaf.com/viewtopic.p ... dd#p313237" onclick="window.open(this.href);return false;
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gbarry42
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 12:57 pm

DNAinaGoodWay wrote:I remember Gary Gid writing that most of the balancing is done in like 45 minutes or so.
There's a bit of history involved, such that in the beginning, the only clues we had about balancing were a page in the service manual that mentioned shunts, and the fact that the charging tapered off at the end. Plus a few reports of the charge coming back on after awhile. Later on, ingineer mentioned that balancing could take place at times other than the 100% charge. Now, with the LEAF Spy, we can see what appears to be balancing (shunting) going on all the time. But we must remember most of what we know is gained empirically, since Nissan won't tell us what actually is going on.

Your results will vary with the charge turning itself back on. Mine never does this, so maybe this battery doesn't get too far out of balance.
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

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DNAinaGoodWay
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Re: How to mitigate a badly out of balance pack?

Fri Nov 15, 2013 1:13 pm

Thanks.

Kinda makes me want to dump Apple and get an Android.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

'17 Bolt LT



6.72 kW Array

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