EVerlasting
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Disable temperature to maintain summer type regen in winter

Thu Aug 07, 2014 8:23 pm

I have a 2012 LEAF SL. Last winter I noticed that my regen dropped significantly during cold weather. For almost five months I experienced very very low regen even when battery pack SOC was very low. Yes, I had the software update done last year in August 2013. Some people have reported that the reduced regen is a result of this software update while some adamantly argue that its due to battery pack losing capacity. I still have all 12 bars. A friend of mine has a 2013 LEAF SL and during last winter both our LEAFs had almost the same mileage accumulated. He drives much more than me everyday. He claims that he experienced absolutely no reduction in his regen during winter. Regardless of what is causing this regen reduction in 2011-2012 models, is it possible to hack our way out of this problem. The only way LEAF knows its winter is by some external temperature sensor. If we disable the temperature sensor, the LEAF may allow us to drive with full regen even in winter. Does anyone know where this sensor is located and how to disable it or pull out it's fuse? I dont mind living with a DTC warning light all winter, as long as I can drive with full regen. Full regen will definately extend winter's reduced range and allow one paddle driving as we do in summer. It wil also reduce wear and tear on the friction brakes which saw more than usual use during last winter. Any help, suggestions and guidance will be most appreciated. This maybe turn out to be a great hack that most of us will do if its possible.
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TickTock
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Re: Disable temperature to maintain summer type regen in win

Thu Aug 07, 2014 8:32 pm

EVerlasting wrote:<snip>The only way LEAF knows its winter is by some external temperature sensor. <snip>
Possibly. Perhaps probably. But not necessarily. It may be the result of how the battery responds to cold weather (pack resistance, capacity, etc.). Also, I wouldn't touch a hack like this unless I was sure I would never be eligible for pack replacement. Circumventing Nissan's efforts to prolong battery life will (understandably) void any claim.

EVerlasting
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Re: Disable temperature to maintain summer type regen in win

Thu Aug 07, 2014 8:58 pm

TickTock wrote:
EVerlasting wrote:<snip>The only way LEAF knows its winter is by some external temperature sensor. <snip>
Circumventing Nissan's efforts to prolong battery life will (understandably) void any claim.
Why does Nissan want to prolong battery pack life of only 2011-2012 models by reducing their regen in cold temps and at the same time increase regen in 2013+ models with the "B" mode in any temps even though all LEAFs from 2011-2014 models have the same battery pack chemistry. It doesn't make sense. There has been some talk in the software update thread that the update may have a glitch (bug) of reducing temp based regen too much in 2011-2012 by mistake. 2013+ models never needed this software update so they are doing just fine regen-wise in cold weather.
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ampitupco
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Re: Disable temperature to maintain summer type regen in win

Thu Aug 07, 2014 10:08 pm

My kingdom to whoever can fix the cold weather regen in my 2012. I firmly believe it is a bug in the last software update.
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Re: Disable temperature to maintain summer type regen in win

Thu Aug 07, 2014 11:54 pm

One thing I firmly believe to be a bug is: Reducing available regen kW as the vehicle's speed increases.

Even with a relatively warm battery, I don't see as much regen as when the car was new. Some, but not all, of that loss should be expected due to degradation.

I wouldn't mess with the temperature sensor, though. That's asking for trouble.
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Re: Disable temperature to maintain summer type regen in win

Fri Aug 08, 2014 2:45 am

My 2013 SV also has reduced regen in cold weather, so it's not limited to first generation Leafs. I don't find it to be a big problem. They may be concerned about thermal stress - cells expanding more (and quickly) over a very large temp range if full regen is provided when the pack is cold.
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Re: Disable temperature to maintain summer type regen in win

Fri Aug 08, 2014 5:07 am

are we sure its the outside temperature its relating too? I would more likely guess its the internal battery pack sensors you would have to turn off. This makes more sense because it would be the battery temperature not outside temperature that would affect braking. That said, I really don't think you want to touch the internal battery temperature sensors - that seems very difficult and I see batteries being bricked.

But I agree with others here, there was definitely a glitch in the software.
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Re: Disable temperature to maintain summer type regen in win

Fri Aug 08, 2014 5:49 am

I wonder if there is a way to increase regen across the board regardless of the weather conditions? I want full 4 bars of regen anytime I completely lift of the accelerator.

TimLee
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Re: Disable temperature to maintain summer type regen in win

Fri Aug 08, 2014 6:21 am

EVerlasting wrote:Why does Nissan want to prolong battery pack life of only 2011-2012 models by reducing their regen in cold temps and at the same time increase regen in 2013+ models with the "B" mode in any temps even though all LEAFs from 2011-2014 models have the same battery pack chemistry. It doesn't make sense. There has been some talk in the software update thread that the update may have a glitch (bug) of reducing temp based regen too much in 2011-2012 by mistake. 2013+ models never needed this software update so they are doing just fine regen-wise in cold weather.
2013 & 2014 did have some modest change compared to 2011 & 2012. Some claim it may have been significant, but bit early to be sure.

But I think it is more likely the significant loss in regeneration was a software error. No special effort to slow capacity loss. But the temperature that is causing the loss is more likely pack, than ambient.

When I had my three year battery test I specifically requested that they NOT do the software update.
It is NOT mandatory.
My regeneration is still similar to when it was new.
Seems to be only modest drop off in regeneration due to battery aging.

My only regret in not having the software change is in not being able to provide data for Stoaty capacity degradation model.

Everyone that had P3227 done should be complaining to Nissan frequently through multiple channels. You never know they might fix it.
I still believe what Andy Palmer said, that their intent was to provide the capacity accuracy changes of 2013 forward to the 2011 & 2012.
But 2013 is a lot different. Three pack temp sensors instead of four. Don't report 12V the same.
Would have been easy to mess up 2011 & 2012 "following" the new 2013 code.

Tim Lee
Chattanooga, TN

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TickTock
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Re: Disable temperature to maintain summer type regen in win

Fri Aug 08, 2014 7:47 am

EVerlasting wrote:
TickTock wrote:
EVerlasting wrote:<snip>The only way LEAF knows its winter is by some external temperature sensor. <snip>
Circumventing Nissan's efforts to prolong battery life will (understandably) void any claim.
Why does Nissan want to prolong battery pack life of only 2011-2012 models by reducing their regen in cold temps and at the same time increase regen in 2013+ models with the "B" mode in any temps even though all LEAFs from 2011-2014 models have the same battery pack chemistry. It doesn't make sense. There has been some talk in the software update thread that the update may have a glitch (bug) of reducing temp based regen too much in 2011-2012 by mistake. 2013+ models never needed this software update so they are doing just fine regen-wise in cold weather.
What we know is the car slowly decreases available regen while drawing power from the battery be it to maintain higher speed, accelerate or run the heater (I need to check the heater bit - I don't think it has been proven) and slowly increases regen when regenerating. Pure speculation, but my theory is they were trying to discourage over cycling (charging and discharging over and over) in vehicles driven by tailgaters. If you do a lot of accelerating and braking pushing charge in and out of the battery each cycle adds wear on the battery so they slowly give you more if you request it steadily. What we also know is the available regen range is more than twice that displayed on the dash bubbles (I've seen 9 bubbles worth when only 4 bubbles show on the dash). So when you think you have "full regen" (all regen bubbles) it really just means you have >45% possible regen. This has the effect of magnifying the perceived impact of any reduced regen from the sw udpate (you may have been moving between 90% and 45% before and never seen a bubble drop but now it varies between 90% and 33% which will cause you to see 2 bubbles drop). So a 12% reduction (or 27% depending on how you look at it) looks like a 50% reduction.

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