Regenerative braking cycling

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Marktm

Well-known member
Leaf Supporting Member
Joined
Jan 21, 2016
Messages
854
Location
Houston, TX
Recently noticed that the amount of regenerative braking cycles - usually when applying light to medium braking effort. The energy "dots" don't seem to reflect this. I've tried to apply the most constant pressure on the brake pedal, however, there is a noticeable oscillation in the amount of braking effort. The speeds during this are definitely high enough that there should be no hydraulic braking required to supplement the regen. Miles per kwh appear normal. No DTCs

Anyone with similar experience?
 
There's a moderately steep hill just before the turn onto my street. An 'S' curve going into it, and condition of the road make my entry into it very near the same speed most of the time, plus I only go about 100 feet before braking and turning. Sometimes I get 4-dots of regen. Sometimes I get 2. The foot pressure seems pretty much the same, Don't know why.

Only actually notice it much on this stretch. Otherwise I'd think braking regen was completely normal. It is a function of speed and pedal pressure so it's not a constant thing.
 
While I'm sure it would be very difficult to replicate the exact brake pedal pressure for any given "regen", that is not what I'm experiencing. What is happening is a very noticeable cycle every split second in the amount of actual braking due to the regen - sort of like an ICE with really badly warped brake disks :mrgreen: .
 
Does the amount of regen only fluctuate when you are decelerating with use of the brake pedal? Or if you decelerate simply by using B mode and taking your foot off the accelerator, does that fluctuate also?

When you have not touched the brake pedal, then the only braking is regenerative, so if it happens there, then the problem is definitely in the regen system. If it never happens until you touch the brake pedal, then it's possible (maybe likely) that the braking system is somehow involved. Causes might include bad ABS sensor/ring on one of the wheels; or if the brake pedal is "fly by wire," there could be corrosion on the contact which reports the brake pedal position; there could be variable fluid pressure in the master cylinder. There could even be a real warped rotor.
 
You could very well be correct - it only happens when braking is (lightly) applied. I was assuming (guess what!) that at speed and light brake application, that the traditional brakes did not get applied - could certainly be wrong on that. I'll keep monitoring it.
 
Causes might include bad ABS sensor/ring on one of the wheels; or if the brake pedal is "fly by wire," there could be corrosion on the contact which reports the brake pedal position;...

The brakes are not fly by wire. I don't think any North American vehicles are allowed to have that yet. The problem could be a common one to electric drive with ABS: the regen could be cutting in and out because of irregular road surfaces.
 
Problem solved:
The brake cycling appeared to be related to cold weather (anything below 40 oF in Houston, TX). During the next "cold" snap my Leaf would not start with the dash showing only partial information. After reviewing all DTCs - most of which were active, I checked the battery voltages - in the low 12's and under load in the high 11's. I slow charged for over 24 hours, but the voltages remained very low under any load. Replaced the battery, cleared all the codes and all is working good. Typical of FLA batteries, final failure can be during the first cold weather.

Lesson learned to me is if you have any strange behavior of any of the Leaf's operations - check the 12 volt system. Low system voltages appear to mess up the control systems - as expected!
 
You may want to search and add your experience to the various 12V battery replacement threads.

Very glad you've solved your problem!
 
Marktm said:
Lesson learned to me is if you have any strange behavior of any of the Leaf's operations - check the 12 volt system. Low system voltages appear to mess up the control systems - as expected!

This could be the answer to half the threads on this forum!
Get a LiFePO4 12v battery (see sig)...and 12v battery issues will be a thing of the past.
 
Back
Top