aarond12
Posts: 365
Joined: Thu Jun 27, 2013 11:42 am
Delivery Date: 17 Oct 2015
Leaf Number: 311353
Location: Dallas, TX

Re: Mod the Regen?

Mon Oct 31, 2016 7:15 am

It was odd to me that the Mitsubishi i-MiEV had full regen (running in "B" mode) even when the battery was full. I guess Mitsubishi realized that, on flat terrain, it takes more power to make the car go than can be regenerated. On a mountain, sure, that's not going to allow regen past 100% charge. It seems that Nissan is just being much more conservative than Mitsubishi was.
2012 Mitsubishi i-MiEV ES (lease ended) • 2015 Nissan LEAF S • Tesla Model 3 reserved
Mods: Matte black Juke wheels, LED headlights and accessory lights, horn, CarPlay receiver

Durandal
Posts: 310
Joined: Wed Sep 21, 2016 8:55 am
Delivery Date: 22 Sep 2016
Leaf Number: 025018
Location: Central Arkansas

Re: Mod the Regen?

Mon Oct 31, 2016 8:32 am

It should be noted that coasting is more efficient than regen, so unless you have some big hill that you're going down, it's better to coast, and just increase your "stopping" (slowing) distance if possible. As soon as I see a red light ahead, unless I'm convinced it is going to turn green before I come to it, I let off the go pedal and coast, and then regen when I know I need to slow down. When I first got the car I was getting 4.2 miles a kWh, but now I'm averaging 4.6 miles a kWh on my commute. (Average speed of 45mph.)
Pulled the trigger on going EV on 10/2016 with a 2012 Leaf, and a Tesla Model 3 reservation expected to receive in June 2018.

arnis
Posts: 742
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: Mod the Regen?

Mon Oct 31, 2016 4:26 pm

aarond12 wrote:It was odd to me that the Mitsubishi i-MiEV had full regen (running in "B" mode) even when the battery was full. I guess Mitsubishi realized that, on flat terrain, it takes more power to make the car go than can be regenerated. On a mountain, sure, that's not going to allow regen past 100% charge. It seems that Nissan is just being much more conservative than Mitsubishi was.


That means 100% charge is not 100% for cells. iMiev charges to around 4.115 volts per cell. Controller may allow to go higher.
4.2V is still safe for lithium cells.
Chevy Volt uses even more narrower SOC window. Regen is totally available at "full charge".

Leaf also charges cell up to 4.135V. But controller does not allow go above that even during regen.

It is not the maximum SOC voltage that degrades cells. it is the time at that voltage.
iMiev expects you to waste that extra 0,5kWh you get if you go down the hill. Pretty reasonable.
Cell chemistry is also a player.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

Limey
Posts: 149
Joined: Wed Jun 05, 2013 8:18 am
Delivery Date: 24 May 2013

Re: Mod the Regen?

Thu Nov 03, 2016 8:03 am

RockyNv wrote:At full regen you are stopping at full brake levels. Once the battery is fully charged to regen capacity the regenerative braking is reduced or completely turned off and only the friction brakes are used. Leaf drivers who live on high mountains have to be careful to not charge their cars fully when at home so that they will not loose regenerative braking on their way down mountain roads making it so they have to rely on friction brakes to keep speed down during their descent.

If you put full regen back into the battery when its at 99% or fully charged they you will likely overheat the battery so that it will fail more quickly. That of course would void the battery warranty since you are defeating the regen cutout that is there to protect the battery. The standard charging cycle is to taper off the charging rate the last few percentage points of the charge cycle since those last few percentage points of charge are the ones that can generate the most heat.

Really look before you leap on hacking the regen program on your Leaf unless the warranty is of no consequence to you.



My issue isn't so much at 99%. But how about 95%?

On my best regen I dont even get a full 1% back. When I am at 95% battery and going downhill, it will cut me from 3 bubbles of regen to two. why do that? The battery obviously has the available storage. I could easily regen on all 4 bubbles for a long time (longer than I could ever find without using a mountain) before I need to worry about over charging the battery.

Yeah, and the warranty isn't a concern anymore. Due to the news EVs coming out with much longer range, the value of the leaf has plummeted. My wife's 3 year older car, that is beat to hell and 50k more miles is worth more than my pristine leaf.

jjeff
Posts: 1456
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: Mod the Regen?

Thu Nov 03, 2016 10:00 am

You never said what year Leaf you had but newer ones(post '12) seem to have a fair amount better regen, even at a relatively high SOC. Of course like you I do wonder why even my '13S only gives a few bubbles at 95% when like you said, it should be able to take much more but I guess we'll never know why Nissan did what they did :? Like you I would like more though.
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

arnis
Posts: 742
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: Mod the Regen?

Thu Nov 03, 2016 12:05 pm

Leaf will adjust regen rate according to maximum charge speed.
Voltage will never go above 4.14V per cell. It will reduce regen if that happens.
After load voltage is a bit lower for short period of time. This is why more regen is available temporarily.

New Leaf has at least 3 bubbles available if SOC 95% or less and battery temp at least 4 bars.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

blimpy
Posts: 115
Joined: Mon Nov 03, 2014 12:36 pm
Delivery Date: 0- 0-2014

Re: Mod the Regen?

Mon Nov 21, 2016 3:37 pm

Unless you re-write the laws of physics... ( please sign over your net worth to me before you do this)
You cannot stuff more water into a full bottle or more electricity into a full battery ( without something exploding).

It didn't take me 5 minutes ( living at the top of a 1000 foot hill ) to discover that there simply isn't
much regen with the batt if nearly full.

If you want to capture the energy.. don't fill the battery.

If you just Want deceleration ( drag) without using friction brakes..

You need a Very Large Resistor... one that can absorb 20Kw of energy. for whatever period you have in mind.
That mofo is going to get very hot.. and probably will be big and heavy.

Or look a lot like a good set of Disc Brakes !
2016 SV purchased 11/2/16 With Subsidies From Sonoma Clean Power, North Sonoma Air Pollution Control District, Evergreen, and State of California, and $15,000 in discounts from Jim Bone Nissan Santa Rosa California. :D Color Me GRATEFUL Long Time Coming !

nerys
Posts: 686
Joined: Tue Sep 09, 2014 10:11 pm
Delivery Date: 09 Sep 2014
Leaf Number: 020441

Re: Mod the Regen?

Tue May 30, 2017 12:05 am

I would love this kind of hack. my 12 leaf constantly cheats me of regen forcing me to use friction brakes more.

I am not talking fully charged here. I am talking 20% charged and its bilking me with 2 regen bubbles

the worst is when you are slowing down with 2 regen bubbles and then AFTER you have slowed too much to get much regen THEN it opens a third or fourth bubbles but now your too slow to freaking use them and once you speed back up it takes them away again. especially in the winter.

extremely annoying and I average 4.9m/kwh much much worse in the winter.
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

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