Brakes Fail upon Powering On

[RegGuheert]

I checked the car aux battery again, this time I left the meter on "min" setting and booted the vehicle up. I ran it through some forward and reversing operations with the original problem still existing. Turned the vehicle off and had a look at the meter and found the min voltage to be 12.15 VDC with average at 13.85 VDC. I would assume 12.15VDC should be adequate to operate the brake system.

I would think so. Those are fairly normal voltages to see in the LEAF.

Last night I gave the vehicle a good run out to pick my mother up at the ferry terminal and back to my place, it was a good 60 km round trip and used 50% battery life. I would assume a good run like that would get the battery nicely charged, but from reading another thread, apparently the battery charge is brought down to 13.1 VDC for whatever reason.

If you assume that about most (older) cars, it would be a decent assumption. That assumption is incorrect for the LEAF since it almost certainly spent nearly the entire drive at a "float" voltage, neither charging nor discharging your battery. In other words, the 12V battery likely had no more charge at the end of the drive than before it.

Spoke to the dealer we are having it towed to nissan

Good idea.

Good luck!

[Ninjarider1978]

If you assume that about most (older) cars, it would be a decent assumption. That assumption is incorrect for the LEAF since it almost certainly spent nearly the entire drive at a "float" voltage, neither charging nor discharging your battery. In other words, the 12V battery likely had no more charge at the end of the drive than before it.

I have come to understand this vehicle does work like ICE vehicles. It does some things in peculiar ways. This not providing a full charge to the aux battery that is responsible for the prime safety feature of the vehicle is really quite dumb in my mind.

Good luck!

We will see what they come up with.

[Ninjarider1978]

I was surprised to find out they even have a regular lead acid battery in them. I figured they would just use a solid state buck switcher to get any other voltage they needed at whatever power level they needed, which is what I guess they must have in order to charge the lead acid battery but likely a much smaller a ampacity due to using the EVSE to charge the 12V normally. Which if they let me plug the vehicle in at greater than 80% charge regularly then I would and the aux battery would be adequately charged without using the main battery. I could be wrong about that though. Would have to perform some testing to prove that. Sorry, just thinking aloud.

[Ninjarider1978]

Update, they took my leaf away to be looked at. Hope to see it again soon.

On the side, my wife and I contacted transport Canada and filed a complaint because of the potential danger this problem has. Normally, when you file something with the government it goes into a black hole never to be seen again, but a person who works at transport Canada contacted my wife looking for more info because there is an open investigation on this problem, which is why Nissan had put a supposed fix out to rectify the problem. Our vehicle was in to get the fix done and 3 days later had this known problem the fix should have fixed. They asked a whole slew of questions like, what was the charge state, was anyone/anything hurt, our vin number, did we have any mods on the vehicle, what were the lights on the dash etc. They want to know what the dealer does to the vehicle.

I made mention of this complaint to transport Canada to our Nissan dealer so hopefully it gets fixed properly.

[dhanson865]

I was surprised to find out they even have a regular lead acid battery in them. I figured they would just use a solid state buck switcher to get any other voltage they needed at whatever power level they needed, which is what I guess they must have in order to charge the lead acid battery but likely a much smaller a ampacity due to using the EVSE to charge the 12V normally. Which if they let me plug the vehicle in at greater than 80% charge regularly then I would and the aux battery would be adequately charged without using the main battery. I could be wrong about that though. Would have to perform some testing to prove that. Sorry, just thinking aloud.

The key concept is the main pack has to be disconnected from all systems when the car is off. This is for safety of mechanics, firefighters, rescue crews, etc.

The 12v is the only battery left connected when the vehicle is off thus you can't charge it while it is off. Any system that would charge the 12v while the car is off would defeat the safety issue mentioned above*.

* the solar panel on the spoiler/roof can feed small low voltage power to the 12v while the car is off but that isn't a safety issue.

End result the 12v battery is used to close the main pack contact every time you turn the car on and it is used for any vampire drain from the cell/gps/radio/lights/key fob reader/etc that is on while the car is "off".

If you want your 12v to last a long time grab a 3a or 4a desulphating charger like a CTEK and charge the car battery several times a year. It's stupid but if you do it then you don't have to worry about what the built in system isn't doing well enough.

edit: http://www.amazon.com/CTEK-56-864-Autom ... B006G14FK8 seems to be on sale right now for ~$47 with prime.

[Ninjarider1978]

Ok, makes sense, seems like the best fix would be for Nissan to properly charge the aux battery when the vehicle is ON. Not sure if that's what the fix was supposed to do or what the deal was but I guess in the meantime I will be topping up the battery occasionally with a separate charger. We will see if Nissan comes back with a low battery charge being the cause of this issue, which is entirely possible since like I mentioned I was on that 60km trip the night previous and apparently the wife sat outside in it waiting for our daughter to finish piano practice, all the while with the heat cranked. She obviously made it home but it's possible with all the parasitic draws it put it in a low state of charge overnight.

[TimLee]

... I ran it through some forward and reversing operations with the original problem still existing.

Last night I gave the vehicle a good run out to pick my mother up at the ferry terminal and back to my place, it was a good 60 km round trip ...

Spoke to the dealer we are having it towed to nissan

Why did you drive a vehicle with brakes that are not working properly 60 km

[dhanson865]

Ok, makes sense, seems like the best fix would be for Nissan to properly charge the aux battery when the vehicle is ON. Not sure if that's what the fix was supposed to do or what the deal was but I guess in the meantime I will be topping up the battery occasionally with a separate charger.

The problem there is the car has no prior knowledge of how long you'll leave the car on in seconds, minutes, or hours. The faster it charges the more damage it can do to the 12v and can cause off gassing (fire/explosion concerns). The slower it charges it may not complete before you turn the car off again.

Another factor is you can only reliably check the voltage on a 12v battery with a steady known load and no charging occurring. But the systems in the car will vary the load as each subsystem is powered up or down. They could make a special diagnostic menu for 12v battery check and charging profile but there is no great way of automatically getting the charge profile right given the three gotchas

1. safe disconnect when off
2. unknown time on / unknown time off
3. variable loads while on and off

Toyota did it way worse with the 2004-2009 Prius, Slight improvement for the 2010-2015 Prius. But the failure mode is the car won't turn on, the brakes are always safe to use because their capacitor dedicated to the brake system works to prevent the issue the Leaf sees.

Tesla has a different issue but still is killing 12v batteries way too often because they have a higher vampire load when the car is off. They have the dash tell you to go to the service center and get a free 12v when it gets too weak. AKA they throw money at the issue (replace the battery proactively at the first sign of weakness). See http://www.teslamotorsclub.com/showthre ... rvice-Tech if you want details.

Nissan has more of an issue with the Leaf that doesn't have the solar panel, probably on par with what you'd see on a current gen Prius. Less of an issue with the Leaf + solar panel as it gives a little bit more charging when the car is in the sun. Not much but better than nothing.

What Nissan needs to do is either

A. make the system immune to the brake issue like Toyota did (redesign, retro fit, hardware change)
B. make the system immune to the issue by pulling a Tesla and have it tell you to replace the battery (software change)*

* The software could tell you to manually charge the battery instead of replacing it but if Leafs start popping up battery warnings even 12v related it'd have a negative connotation.

End result is Hybrid or EV there is no easy answer. If you as the end user maintain the 12v your issues will be less than if you trust the car to try and do it on its own.

[TimLee]

...
What Nissan needs to do is either

A. make the system immune to the brake issue like Toyota did (redesign, retro fit, hardware change)
B. make the system immune to the issue by pulling a Tesla and have it tell you to replace the battery (software change)*

* The software could tell you to manually charge the battery instead of replacing it but if Leafs start popping up battery warnings even 12v related it'd have a negative connotation.
...

But doing nothing because of negative connotations, which is what they seem to have done so far, seems like a really bad long term choice.

Could result in NHTSA issues, fines, lawsuits, etc.
Lots of past experience from Toyota and GM to indicate do nothing is a bad choice.

This topic discusses braking issue. But other MNL topic has discussed loss of propulsion which may also be related to 12V problem.
Braking problem seems more of a risk, but GM switch problem that caused loss of power has been documented to have caused quite a few deaths.

[dhanson865]

...
What Nissan needs to do is either

A. make the system immune to the brake issue like Toyota did (redesign, retro fit, hardware change)
B. make the system immune to the issue by pulling a Tesla and have it tell you to replace the battery (software change)*

* The software could tell you to manually charge the battery instead of replacing it but if Leafs start popping up battery warnings even 12v related it'd have a negative connotation.
...

But doing nothing because of negative connotations, which is what they seem to have done so far, seems like a really bad long term choice.

Could result in NHTSA issues, fines, lawsuits, etc.
Lots of past experience from Toyota and GM to indicate do nothing is a bad choice.

This topic discusses braking issue. But other MNL topic has discussed loss of propulsion which may also be related to 12V problem.
Braking problem seems more of a risk, but GM switch problem that caused loss of power has been documented to have caused quite a few deaths.

Yep, I'm not saying I'm happy with it and nothing should change. I'm just saying I charge my battery with a CTEK in addition to the Nissan provided systems. Hopefully some day down the road I won't have to bother.