Just today, I have had this dreaded condition happen to me. I have a description of the failure following what I want to say about batteries.
I had read most of this thread a few months ago and was inclined to believe it would turn out to be a problem with batteries. Now I am pretty sure it is not. I got home five minutes after the lights had popped on and the car had malfunctioned, then powered it down and checked the battery voltage within two minutes of arrival. It was perfect, at about 12.56V. My drive home was not enough to really charge it, and the car being an SL with a PV panel, and being parked in the bright sun before and after the "bad thing" happened would tend to indicate it was not an undercharged 12v battery causing the failure. Perhaps some of these folks are having 12V failures, but, I think in my case it is NOT. I had no other issues, like radio or anything, just the brakes.
Let me clear up some technical errors that have come up in this thread. The speculation that Nissan has the charging profile all wrong is, well, cuckoo. Without having access to the software and the comments and really understanding what their strategies for maintaining the 12V is, you cannot really infer much of anything about it. What is your explanation for the big voltage spikes seen repeated in the graph? My best explanation is that Nissan is using a momentary "overcharge" to evaluate the 12V and adjust the system voltage accordingly. It is done all the time in charging systems for battery packs, and I see a lot of this stuff. The overall voltage dropping could be the result of temperature, surface charge etc. The graph is not detailed enough to tell anything. If you guys want to do the belt and suspenders thing of putting a maintainer on your 12V, well go for it. You aren't harming anything. I ran my 2012 leaf for three brutal MN years and never even looked at the 12V (and I own, like, five maintainers).
Let me also clear up some misinformation. The resting voltage of a lead battery goes down as the ambient temperatures fall. It is a chemical machine and the chemical reactions weaken and slow with decreasing battery/ambient temps. It is uber logical that they will DECREASE in resting voltage with lower temps. By the same token, you have to INCREASE the charging voltage to compensate for colder weather. Perhaps this is where the confusion has arisen. My little battery was at zero to fifteen degrees and reading just under 12.6 volts-perfect. On a warm day it would be over 12.6 volts.
So lets not derail this thread by picking apart Nissan's 12V battery strategy when we don't even know it is a battery problem, nor a problem with their software strategy. Someone mentioned the Gen II Prius having battery problems. I work on hundreds of them in a Prius specialty repair shop. In this climate there is nothing wrong with them- not the cars, the software, or the batteries. The batteries last just as long as a starting battery does in a Chevy. Five years and you replace it before it does something bad to your car. The complaints I hear about them seem to be in hot climates. That is another story. I know a hybrid shop in Colorado who was using Optimas for Prius and had to warranty virtually every one of them. I stick with the Toyota battery for '04 and up Prius. Maybe Optimas are better in the hotter areas, but they su*k in this climate.
I will be really thrilled if this turns out to be something simple like a bad batch of batteries....
So this happened to me today and I have not made it back to my shop to get the scan tool to check for codes, and to electronically test the 12V battery. You can bet I will be updating this. My other 2015 has had no issues.
January 16 2016
I had the brake fail upon startup condition happen to me. I have no accessories or any auxiliary loads plugged into my car anywhere. The car has about a thousand miles on it and was delivered new in November. Car is typically driven 10 to 20 miles every day. Nissan performed the latest brake software upgrade before I was allowed to take delivery of the car in November.
I had charged the car early Friday, the day before it happened and left it out that day and overnight. Our temps were around 15F Friday and dropped to below zero Saturday. Saturday afternoon, I started off with a full pack and two temp bars, drove it two miles, and parked it for about an hour. The sun was shining brightly Saturday and the car being an SL was likely getting good current from the solar panel most of the day. I got into the car, powered up and started backing out into the street. Lots of strange noises were happening from the firewall area, possibly both the motor bay and the cabin sides. I am a very in tune diagnostic auto technician, and none of the noises then were particularly identifiable or disturbing. They were definitely not typical ABS noises.
It is a brand new car, so I was not particularly alarmed by the noises, because it is one of the coldest days I have had the car. But as I turned forward and started driving I noticed a host of warning lights were lit on the dash. BRAKE (RED); ABS, Slip indicator (not the slip OFF) and braking icon (YELLOW) , plus the warning triangles. I decided to pullover and take a picture of the dash all lit up and discovered no brakes until the pedal was near the floor. Then the brakes aggressively engaged and the ABS went nuts chattering/activating. This was on dry pavement, where the ABS would not be normally activating. I cycled the power and started out again, with the exact same symptoms. I did this a third time, and it was just a hosed a before.
I had back streets to get home 2 miles, so I tested the brakes and concluded they were likely to be usable for the short drive, and I also had the e-brake pedal to stop if necessary. I was disinterested in walking home in the below zero temps. Who knows what the wind chill was! On the drive home (another two miles), the brakes were barely functional. They would only work with the pedal hovering near the floor and when they did activate, they would activate the individual wheel brakes separately and randomly. At one point, as I rolled up to a stop light, both fronts locked-up and I screeched to a halt. When I arrived home, I immediately powered-off the car and ran to get my voltmeter. It showed 12.56. Just about what I would expect for a pretty darned cold battery.
I got my feet warm and went out less than an hour later to see if it was still hosed, and the car acted like nothing had happened. It readyed and drove normally.
I will see if there are any codes and test the battery for issues ASAP. Build date 04/15 Can't wait to see what this turns out to be!
2015 Grey SL Nokian WR G3 tires
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