No downhill regen above 80%, what is the reason(ing)?

So recently I made my trip return from Mt Baldy. The trip uphill requires about 9-10 bars from Claremont, so I stop and get a charge somewhere, sometimes at at SCE in Irwindale (to 100%, or the chargers actually near the base of the hill easily found online).

While up there, used level 1 trickle charging to get to 80%, and headed down from 6,000 feet. Once down the 5,000 drop, I really could use 100% to get to my destination of West Los Angeles (zipping along at 65-70 MPH is a less stressful drive on freeways)...

However, the regen stopped at 80%, leaving me wearing the brake pads, and getting no added energy. It seems if I want the full 12 bars of charge for my now degraded battery 2011 LEAF, I simply have to just charge up to full at the starting summit.

As the topic says: no regen above 80%, what is the reason(ing)?

BTW, I did a search and didn't glean any discussion....

I think it starts allowing some regen at about 97-98% and full regen seems to be available below 95%. If you have a really long downhill, then if you charge it above the threshold, then it limits how much regen can be used.

I don't know why you lost regen, unless the battery got too hot?

NeilBlanchard said:

I don't know why you lost regen, unless the battery got too hot?

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Neil, thanks for considering... The battery was actually cold... Around 40-50 degrees is my best guess. Anyway, next time I am just going to charge to 100% as the 5,000 feet downhill added nothing from 80%, and I really need all the juice I can get for the freeway back to the Westside of Los Angeles from Claremont. Either way I was wearing the brake pads.

Lastly, as an aside, the Leaf Spy Pro is a huge advantage when one wants to keep up with freeway traffic in the midst of an end of range run, and not be deluded, or freaked out, by the GOM.

Still, I would like to know why the regen was non existent. Makes no sense in this application.

No other knowledgeable folks can explain why no regen energy?

I agree w/ Neil as I get regen to about 95% cold or hot. Bat is 57.91Ah ,88% soh. How degraded is yours? Is it possible limited regen is associated directly in conjunction w/ lesser soh?

Do a search on the P3227 update for the 2011 and 2012 LEAFs and you'll find lots of discussion about the loss of regen after the update specifically at battery levels of 80% and higher. As far as we can tell this is something Nissan did to prolong the life of the battery.

Those of us who live effectively at the top of a hill experience this all the time, and yes it's annoying.

I think it's a temperature issue. For whatever reason, the BMS seems to limit regen at temps below about 50 F, and more so with the earlier model year LEAFs than with the 2013 or later. This is well documented by mountain residents who would love to use regen on their downhill legs.

even with a 2013, if the battery is at 83%, and the battery is down in the 30-40 degree range, I might only get 5 to 10 KW of regen.

So your trip might go better if you can start with a nice warm 70 degree and hopefully it is not a cold day up top so that it doesn't cool down too much.

As you suggest, if you need maximum range at the bottom of a hill you need to start at "100%". For reasons unclear, you can never regen your way back to 100% even at warm temperatures. When the battery is cool, say 12ºC, regen is limited on 2011/2012 LEAFs. When the battery is cold, around freezing, regen is sharply limited even at low SOC. When the battery is very cold, say -10ºC, regen is almost gone even at low SOC levels. This reduced regen was exacerbated by the P3227 update.

Newer LEAFs have been reported to have regen up to fairly high SOC levels but this is not true for 2011/2012 LEAFs. And, yes, as someone who lives on a mountain the pathetic regen in a LEAF is disappointing. The reduced regen after the P3227 update is downright irritating.

One never-discussed advantage of a future LEAF with a double-size battery is that Nissan might offer decent regen for the first time. If they deign to do so.

I virtually never see over three bubbles of regen anymore regardless of temperature or SOC, and often less...

My 2015 regens like crazy. I have a small hill when leaving home and I find the energy use screen is showing me some regen (10kW) even when leaving fully-charged. I was quite surprised by this as it never happened with the 2012, even when new.

I get full regen after just a short period of driving; still in the 90's SOC. Though it hasn't yet been much below 50F here.

All, thanks for the confirmation and thoughts.

So it appears that my 2011 will not be able to charge up going down a hill to 100% unless Nissan changes the energy mapping of the software. Like some of you corroborate, for those whose regular commute starts at the top of a large elevation drop, who need a full charge, this is more than a thorn in the side. I doubt it helps the battery life all that much.

I still like the car but do have envy for the newer faster onboard chargers, and now the regen performance.....

JimSouCal said:

...I still like the car but do have envy for the newer faster onboard chargers, and now the regen performance.....

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My feelings also. The car fits my needs well but a faster charger and better regen would be a big help. Not that I can justify the huge cost to upgrade to a 2015 LEAF for those two improvements: I'm saving my funds for a future Tesla Model III (I hope).

This issue is one that I have come to know all too well. In general, we no longer take our 2011 LEAF down the mountain we live on (4900' descent) unless we are going to have convenient access to charging below, or if we are going no further than the very base of the mountain. The regen is lousy except at relatively low states of charge, and relying only on the friction brakes is unsafe. My wife recently tried charging to 100% before making the descent (to allow her to do some shopping down below), and even with multiple, brief stops to let the friction brakes cool, they were excessively hot and the car shook during braking.

We've mostly come to accept that the 2011 LEAF is good for driving around within our mountain area, and it is best to use the Prius whenever we need to leave the mountain. If I were a "flatlander", I'd not hesitate to drive a LEAF into high mountains provided I could descend with no more than 60% charge, or less during the colder months.

While I appreciate the LEAF, it is definitely our last short-range EV. The next one needs to have a lot of battery capacity and consequently better regen (not to mention AWD).

abasile said:

While I appreciate the LEAF, it is definitely our last short-range EV. The next one needs to have a lot of battery capacity and consequently better regen (not to mention AWD).

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You've been a pioneer, willing to take the risk to buy a LEAF right out the gate. If there were such a thing as LEAF awards of merit, you'd rate one on counts of taking on then unknowns: cold, elevation, snow, and a few I surely overlook.

But just saying, I didn't have any issues coming down from Mt. Baldy on the car shaking using the brakes. Just no regen... And the area known as "the switchbacks" is major steep.

I don't want to take too much credit for being a LEAF pioneer, as I haven't done much more than use the car, and comment here from time to time. I will say that in mountain environments, electric drive really shines in comparison to ICEs which are generally forced to operate at suboptimal efficiency on uphills and waste potential energy on downhills. The cooler temperatures can help with battery longevity. With more range and AWD, EVs will make ideal mountain vehicles. (I'm waiting for prices to come down on dual-motor Teslas...)

JimSouCal said:

But just saying, I didn't have any issues coming down from Mt. Baldy on the car shaking using the brakes. Just no regen... And the area known as "the switchbacks" is major steep.

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Admittedly my LEAF's friction brakes have taken more than the normal amount of "abuse". I used them plenty during the almost two years that I used the LEAF to commute down the mountain. And yes, sections of Mt. Baldy Rd. can be quite steep; I know that road well, and I'm glad you had no safety issues on the descent.