Brakes Fail upon Powering On

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dhanson865 said:
... I'm just saying I charge my battery with a CTEK in addition to the Nissan provided systems. ...
I do to.

With the five times typical drain on the 12V caused by the Bluetooth adapter, which I find more trouble to unplug even though it is on an OBDII extension cable due to time to re-pair with phone, I hook up CTEK every time I charge the LEAF.

It doesn't do much effective top off while LEAF is charging, but when LEAF charging finishes I disconnect the J1772, and restart the CTEK analysis and topping off and only disconnect it from the 12V before I drive off.
 
Thought these might be of interest, some notes out of the 2012 service manuals (June 2014 Rev) related to 12V battery charging.

EVC-48: Automatic 12V Battery Charge Control
DESCRIPTION
The automatic 12V battery charge control is a control to reduce the frequency of battery discharge by automatically charging the 12V battery in case the 12V battery voltage is low when the key switch is turned to ON or the vehicle is left unattended for a long time.
When VCM judges a need for automatic charge, VCM controls the DC/DC converter and the system main relay and charges the 12V battery using the Li-ion battery power.
For 12V battery charge control during READY condition, refer to EVC-48, "POWER VOLTAGE VARIABLE CONTROL SYSTEM : System Description".

PG-9: 12V Battery
Note: VCM charges the 12V battery for 5 minutes when the vehicle power is not turned on for a set period of time (120 h).

EVC-48: Power Voltage Variable Control System
DESCRIPTION
The power voltage variable control system reduces the electric power consumption from the Li-ion battery by
varying the DC/DC converter output in a range from 13 V to 15 V according to the use status of electric equipment and the 12V battery status.
CONTROL DESCRIPTION
The battery current sensor (with battery temperature sensor) measures the battery charge/discharge current and the battery ambient temperature.
VCM judges the battery status and the use status of electric equipment based on those signals, determines a target output voltage, and transmits a target DC/DC output power signal to the DC/DC converter.
The DC/DC converter adjusts the output voltage to the target power generation voltage based on the received target DC/DC output power signal.
In addition, when there is no power voltage signal or when some error is occurs in the variable voltage control system, the DC/DC converter outputs 14 V.
 
miscrms said:
Thought these might be of interest, some notes out of the 2012 service manuals (June 2014 Rev) related to 12V battery charging.
...
EVC-48: Power Voltage Variable Control System
DESCRIPTION
...
VCM judges the battery status and the use status of electric equipment based on those signals, determines a target output voltage, and transmits a target DC/DC output power signal to the DC/DC converter.
...
The problem with the 12V battery charging system in he LEAF lies in this part. Unfortunately, when the car is OFF, the VCM cannot know how much energy is being used from the 12V battery. As a result, it makes an estimate when you start the vehicle how much charge to replace. Unfortunately, it is overly optimistic in many operating scenarios, resulting in only a fraction of the energy which was lost being replaced. The unfortunate result of that is a 12V battery which spends most of its life at 60% SOC, which leads to sulfation (hardening of the lead sulfate) and early death.

The good news is that the battery uses very little water in the LEAF's charging regime. If you charge it to full occasionally with a good quality trickle charger, it should last a very long time.
 
RegGuheert said:
The problem with the 12V battery charging system in he LEAF lies in this part. Unfortunately, when the car is OFF, the VCM cannot know how much energy is being used from the 12V battery. As a result, it makes an estimate when you start the vehicle how much charge to replace. Unfortunately, it is overly optimistic in many operating scenarios, resulting in only a fraction of the energy which was lost being replaced. The unfortunate result of that is a 12V battery which spends most of its life at 60% SOC, which leads to sulfation (hardening of the lead sulfate) and early death.
Thanks for the explanation; that pretty much clears up the mysteries of the LEAF's poor 12V reliability. Obviously, the VCM's 12V battery monitor functions should be powered from the 12V battery always, and not just when the car is ON. Low power design is a hot engineering topic these days; it should be completely feasible to do. And just TRY to claim it would be more expensive per car than replacing 12V batteries every year or two...
 
Levenkay said:
Obviously, the VCM's 12V battery monitor functions should be powered from the 12V battery always, and not just when the car is ON. Low power design is a hot engineering topic these days; it should be completely feasible to do. And just TRY to claim it would be more expensive per car than replacing 12V batteries every year or two...
Even if it did/does that, it would have a very difficult time monitoring the load current when the car is off. The reason is that the monitoring system needs to be able measure hundreds of amps, but it would need to be able to resolve about 5 mA in order to know what is going on when the car is off. If the system used a 1 mohm shunt, that would mean an instrumentation system capable of resolving 5 uV with about 20 bits of resolution. (Alternatively, multiple shunts could be used for different loads on the battery, which may be what is done.)

Another solution is simply to be pessimistic about how much energy was drained while the car was off and replace more than what it thinks is needed. That would cause a bit more water to be consumed, but it would still be an improvement over the current approach as well as older-style charging systems which hold the voltage at 14.5V when the vehicles is on.
 
poiuy09 said:
Exact same thing happened to me today. Started my 2013 Nissan Leaf and put it in reverse and almost immediately the car started moving back. Since my drive way has a considerable slope, the car moved fast. Brakes felt soft and no resistance. Had to slam the brakes pretty hard to the floor to get the car to stop. Turned the car off and started it back on after few mins. Still the same issue. Moved the car to Drive and it did the same thing. Slammed the brakes again hard to stop the car. Left the car there for a while and started it after an hour and everything seems normal now. Took the car to the dealer (Corona Nissan) and explained the problem.

What did the dealer end up doing? I'm experiencing the same thing and have an appointment to bring my Leaf in to Corona Nissan tomorrow.

For those keeping track:
2015 S Model
<10,000 miles

I had the T/M System Malfunction, where not only did the breaks not work, but basically nothing worked. Stereo console got stuck in a reboot loop. I charged the 12v using a battery tender I use on my motorcycle (1.5 amp), and have now had the same problem but instead of T/M System Malfunction I got the red BRAKE light and yellow ! in a circle.

I also have had an issue that when I park the car and turn it off, a high pitch note is played, but no lights show up on the dash. Opening closing door doesn't do anything, walking away doesn't do anything. Turning the car on/off (foot on brake) causes the chime to stop.
 
Have any Leaf owners tried switching to a good quality deep cycle AGM type battery? I went to an Optima Yellowtop on my 2005 Prius, which is also notorious for undercharging 12V batteries, and have had no issues for 5 yrs. Even in Phoenix, which also tends to also be tough on 12V battery life.

It does seem surprising to me that the Leaf uses a flooded type battery, as well as a conservative charging routine. The only advantage of a 12V flooded I can think of is its tolerance to more aggressive charging. I guess the explanation is in the "reduces the electric power consumption from the Li-ion battery" statement, seems like they went a bit too far in the efficiency direction.

The Leaf does also use a 12V backup capacitor bank as someone else mentioned the Prius does. So its a little surprising that it could still get into this sagging voltage failure mode if that is indeed the cause. Unless I guess the 12V voltage is just not sufficient to charge the cap bank sufficiently? But that voltage should come up quickly as soon as the DC/DC converter engages when going ready? There are DTCs in the brake system and VCM for low 12V voltage, but they don't seem to trip until 10V or so.

Still it doesn't seem like a total brake failure should be possible even if the electronic control system fails completely. According to the manuals (and my own experimentation) there is still manual hydraulic braking force available in the event of a complete system failure. In my case this was simulated by disconnecting all control and power connections to both the ABS and IBU/master cylinder. Without the boost pump I will say the braking is very heavy, and the pedal position quite low from what I recall. So if the brake boost motor cuts out it may well feel like you've lost the brakes, but a firm pressure on the pedal should still stop the car.

Additionally its perhaps worth noting that the parking brake can (according to the manuals) be used while the vehicle is in motion to apply mechanical cable driven force to the rear brakes as long as the handle is pulled up. Of course this motor does depends on 12V power, but not sure how sensitive it is to voltage.

Rob
 
DesertSprings said:
poiuy09 said:
Exact same thing happened to me today. Started my 2013 Nissan Leaf and put it in reverse and almost immediately the car started moving back. Since my drive way has a considerable slope, the car moved fast. Brakes felt soft and no resistance. Had to slam the brakes pretty hard to the floor to get the car to stop. Turned the car off and started it back on after few mins. Still the same issue. Moved the car to Drive and it did the same thing. Slammed the brakes again hard to stop the car. Left the car there for a while and started it after an hour and everything seems normal now. Took the car to the dealer (Corona Nissan) and explained the problem.

What did the dealer end up doing? I'm experiencing the same thing and have an appointment to bring my Leaf in to Corona Nissan tomorrow.

For those keeping track:
2015 S Model
<10,000 miles

I had the T/M System Malfunction, where not only did the breaks not work, but basically nothing worked. Stereo console got stuck in a reboot loop. I charged the 12v using a battery tender I use on my motorcycle (1.5 amp), and have now had the same problem but instead of T/M System Malfunction I got the red BRAKE light and yellow ! in a circle.

I also have had an issue that when I park the car and turn it off, a high pitch note is played, but no lights show up on the dash. Opening closing door doesn't do anything, walking away doesn't do anything. Turning the car on/off (foot on brake) causes the chime to stop.

An update on the vehicle is they still have it. They called the day it went in and said they updated the firmware again. I asked what the difference was between fridays firnware upgrade and this new one. He said that they are instructed to put this new fireware on if the other one doesnt work. He mentioned the vehicle was working fine again but then asked if it was ok to keep the vehicle until the next day for observation and so they could consult with nissan canada and nissan japan to ensure the problem is fixed. I ablige and patiently wait for a call the next day. At 4pm they called and said they would like to keep it longer and they would give me a rental vehicle if i needed it. I asked how long they expected to need it, he said hopefully just a day but it could be longer. To be safe i accepted the rental because these things alway take longer than expected. My wife and i believe that because our vehicle experienced the problem after the fix was applied that it makes it good to study. So they asked to keep it longer so they can ensure the update will work and put it through its paces. They can then hopefully use that info to apply to other vehicles. I think us raising the issue with transport canada has helped push it this direction.

That being said, i really want it back because the replacement ICE sucks bad.

Will keep you updated if they get back to me today. I asked for constant communications but the tech i was in contact with is off today so i expect to hear from them tomorrow.

Mike
 
miscrms said:
Have any Leaf owners tried switching to a good quality deep cycle AGM type battery? I went to an Optima Yellowtop on my 2005 Prius, which is also notorious for undercharging 12V batteries, and have had no issues for 5 yrs. Even in Phoenix, which also tends to also be tough on 12V battery life.
Several LEAF owners have done this. One issue is that the 13.1V float voltage used by the LEAF can actually be LOWER than the standing voltage for these batteries when fully charged. In other words, the LEAF charger may actually DISCHARGE the battery if fully charged rather than simply failing to charge it. At least one owner has installed a Li-ion 12V replacement battery.
miscrms said:
It does seem surprising to me that the Leaf uses a flooded type battery, as well as a conservative charging routine. The only advantage of a 12V flooded I can think of is its tolerance to more aggressive charging.
They are also cheaper.
miscrms said:
I guess the explanation is in the "reduces the electric power consumption from the Li-ion battery" statement, seems like they went a bit too far in the efficiency direction.
Agreed.
miscrms said:
The Leaf does also use a 12V backup capacitor bank as someone else mentioned the Prius does.
That's true, but only for MY2011/2012. In MY2013 and later LEAFs, backup braking power is provided by a hydraulic acumulator.
miscrms said:
So its a little surprising that it could still get into this sagging voltage failure mode if that is indeed the cause. Unless I guess the 12V voltage is just not sufficient to charge the cap bank sufficiently? But that voltage should come up quickly as soon as the DC/DC converter engages when going ready?
It seems that the ultracapacitor in the MY2011/2012s must be charged above a certain level before the brakes will work, even if the voltage in the car is fine. I know this because my dealership could not deliver the car to me after reprogramming the brakes due to the technician not knowing how to recharge the ultracapacitor. But it did eventually charge up on its own.
miscrms said:
Still it doesn't seem like a total brake failure should be possible even if the electronic control system fails completely. According to the manuals (and my own experimentation) there is still manual hydraulic braking force available in the event of a complete system failure. In my case this was simulated by disconnecting all control and power connections to both the ABS and IBU/master cylinder. Without the boost pump I will say the braking is very heavy, and the pedal position quite low from what I recall. So if the brake boost motor cuts out it may well feel like you've lost the brakes, but a firm pressure on the pedal should still stop the car.
The technician who had the problem with my car said the pedal went straight to the floor..
miscrms said:
Additionally its perhaps worth noting that the parking brake can (according to the manuals) be used while the vehicle is in motion to apply mechanical cable driven force to the rear brakes as long as the handle is pulled up. Of course this motor does depends on 12V power, but not sure how sensitive it is to voltage.
The electrical parking brake system was replaced with a mechanical one starting with MY2013.
 
miscrms said:
Have any Leaf owners tried switching to a good quality deep cycle AGM type battery? I went to an Optima Yellowtop on my 2005 Prius, which is also notorious for undercharging 12V batteries, and have had no issues for 5 yrs. Even in Phoenix, which also tends to also be tough on 12V battery life.

It does seem surprising to me that the Leaf uses a flooded type battery, as well as a conservative charging routine. The only advantage of a 12V flooded I can think of is its tolerance to more aggressive charging. I guess the explanation is in the "reduces the electric power consumption from the Li-ion battery" statement, seems like they went a bit too far in the efficiency direction.

The Leaf does also use a 12V backup capacitor bank as someone else mentioned the Prius does. So its a little surprising that it could still get into this sagging voltage failure mode if that is indeed the cause. Unless I guess the 12V voltage is just not sufficient to charge the cap bank sufficiently? But that voltage should come up quickly as soon as the DC/DC converter engages when going ready? There are DTCs in the brake system and VCM for low 12V voltage, but they don't seem to trip until 10V or so.

Still it doesn't seem like a total brake failure should be possible even if the electronic control system fails completely. According to the manuals (and my own experimentation) there is still manual hydraulic braking force available in the event of a complete system failure. In my case this was simulated by disconnecting all control and power connections to both the ABS and IBU/master cylinder. Without the boost pump I will say the braking is very heavy, and the pedal position quite low from what I recall. So if the brake boost motor cuts out it may well feel like you've lost the brakes, but a firm pressure on the pedal should still stop the car.

Additionally its perhaps worth noting that the parking brake can (according to the manuals) be used while the vehicle is in motion to apply mechanical cable driven force to the rear brakes as long as the handle is pulled up. Of course this motor does depends on 12V power, but not sure how sensitive it is to voltage.

Rob

+1

I have used red top Optima batteries in my gasoline engine vehicles in Phoenix for many years and they always last longer than conventional batteries (unless the charging system overcharges them). I purchased a yellow top Optima deep cycle battery for the 2011 Leaf when the original flooded-cell Nissan battery failed even though I could have gotten a replacement from Nissan under warranty. It would be in the 2015 if the insurance company's storage yard would have let me remove it after the 2011 was declared a total loss. I believe the Leaf's charging algorithm is ideal for the yellow top Optima and I will replace the original Nissan battery as soon as it gets weak.

I have also tested the brakes without assist on both the 2011 and 2015 and found that the hydraulic brakes still function, but they require a lot of pedal pressure and the pedal is only about 1/2-inch above the floor. To someone who has not tried this it could seem like the pedal was going to the floor without applying the brakes.

Gerry
 
Or Exide Edge AGM.

From the one time I experienced the brake failure while parking when 12V had bad cell, I agree the brakes may have actually finally worked as I did not hit the car behind me.
But even when moving at slow speed and there is only three or four feet, I really thought I was going to hit it and that the brakes totally failed.

Similar to GM ignition switch issue.
Yes the cars would steer.
Have you tried steering a car with the power assist not working :?:
Really difficult.
 
TimLee said:
Or Exide AGM.
Again, note that the Exide AGM has a standing voltage above 13.2V when fully charged:

69800_s_LEAF_Battery_Voltage_7_day.png


Member 69800 took that data. Note the voltage at the beginning of April 6 before he drove the LEAF. The point is that the LEAF's charging system DISCHARGED this battery when it was driven by operating at a voltage of 13.1V. Without occasional charging using a high-quality trickle charger, this battery will suffer he same fate as a flooded battery: sulfation. It might even happen more quickly due to the higher battery voltages resulting in a lower average SOC.
 
Got a call from the dealer (Corona Nissan), they said there's 8 or 9 codes stored, from different components, so their Leaf guy (they have only one) is required to research and troubleshoot each individual code.

I'd asked them specifically to load-test (or whatever the correct term is) the 12v battery, but it wasn't specifically listed on the work order. When I pointed this out, they assured me it would be one of the tests they run, but would make a point to specifically mention it to the Leaf tech.

It's 2pm, so I'm not very hopeful that I'll get the car back before the weekend. Luckily I still have my old ICE as backup and for longer trips.

(This AM it was cold enough for frost to form on the roof of my house (Leaf was in the carport, protected from wind). When I started the Leaf up to take to the dealer, the red brake light was on and the orange ! was lit. Pumping the brakes before putting it into gear caused the lights to turn off, and the car to maintain braking when shifting into gear)
 
Not sure I agree with the conclusion from the chart. When the DC:DC is on it looks pretty steady at ~13.1V. That should be beyond 100% SOC even for the AGM, so its not discharging the battery. Anything over 13V or so shown on the battery initially is likely surface charge. The occasional spikes to ~14.4V should be the VCM increasing the output voltage to charge the battery rather than maintain.

Any idea what the temperature was like for this April data? 100% SOC even on AGMs can be as low as 12.6V in the cold. The way its ramping down consistently reminds me of a battery acclimating to temperature and/or shedding surface charge. Its interesting to note that the voltage sags before the DC:DC kicks in, and after it kicks out (but before the loads shut off) seem to remain relatively constant over time, and almost looks like resting voltage is trending toward that same voltage.

Interesting chart:
http://www.exide.com/Media/files/Downloads/TransAmer/Battery%20Care%20and%20Maintenance/Battery%20Charging%20&%20Storage%20Guidelines%20%205_9_13.pdf

While 90% SOC Voltage is a little higher for the AGMs, they are same for 70% and lower. Also trickle / float voltages are similar, but absorption charging voltage and bulk charging termination voltage are actually lower on the AGMs.

AGMs also typically have much better internal resistance, charging efficiency, and much lower (up to 10X) self discharge rate.

In either case, flooded or AGM, putting a charger on it periodically is certainly not a bad idea.

Rob
 
DesertSprings said:
Got a call from the dealer (Corona Nissan), they said there's 8 or 9 codes stored, from different components, so their Leaf guy (they have only one) is required to research and troubleshoot each individual code.

I'd asked them specifically to load-test (or whatever the correct term is) the 12v battery, but it wasn't specifically listed on the work order. When I pointed this out, they assured me it would be one of the tests they run, but would make a point to specifically mention it to the Leaf tech.

It's 2pm, so I'm not very hopeful that I'll get the car back before the weekend. Luckily I still have my old ICE as backup and for longer trips.

(This AM it was cold enough for frost to form on the roof of my house (Leaf was in the carport, protected from wind). When I started the Leaf up to take to the dealer, the red brake light was on and the orange ! was lit. Pumping the brakes before putting it into gear caused the lights to turn off, and the car to maintain braking when shifting into gear)

Would be interesting to see what the codes are, if you can get a list.

Rob
 
miscrms said:
Not sure I agree with the conclusion from the chart. When the DC:DC is on it looks pretty steady at ~13.1V. That should be beyond 100% SOC even for the AGM, so its not discharging the battery. Anything over 13V or so shown on the battery initially is likely surface charge.
Nope. Resting voltage is clearly seen to be 13.25V for about six hours. There is a load on the battery during that time, so it is not surface charge.
miscrms said:
The occasional spikes to ~14.4V should be the VCM increasing the output voltage to charge the battery rather than maintain.
That's right. And since these spikes are too short, the voltage drops with time.
miscrms said:
Any idea what the temperature was like for this April data? 100% SOC even on AGMs can be as low as 12.6V in the cold.
Lead-acid battery voltage goes UP when it is cold, not down. You won't see 12.6V for a full resting battery unless it is quite hot. I've never seen the LEAF OEM battery hot enough to give such a low resting voltage wen full.
miscrms said:
The way its ramping down consistently reminds me of a battery acclimating to temperature and/or shedding surface charge.
It's simply discharging due to the load of the LEAF on the battery.
miscrms said:
Its interesting to note that the voltage sags before the DC:DC kicks in, and after it kicks out (but before the loads shut off) seem to remain relatively constant over time, and almost looks like resting voltage is trending toward that same voltage.
The loaded voltage is typically around 12.3V. Unfortunately, the LEAF will continue to discharge the battery until the resting voltage is around that level. That is because charging at 13.1V only charges the battery to around 60% SOC.
miscrms said:
In either case, flooded or AGM, putting a charger on it periodically is certainly not a bad idea.
Agreed. Too bad the algorithms don't simply keep it charged so we don't have to do it.
 
Sorry, I wasn't able to get the codes. They didn't call me to pick up until 5pm, and I just barely got there before 6 which is the cut off for picking up. All the techs had gone home.

But per what they told me on the phone, all the codes were likely caused by low 12v voltage. When they originally tested my battery when they first brought it into the shop, it passed. However after looking into the codes, they retested the battery and it failed.

So I was likely right on the edge. One of the consistent factors during my issues was much colder than typical weather, which probably was the tipping point.
 
RegGuheert said:
Lead-acid battery voltage goes UP when it is cold, not down. You won't see 12.6V for a full resting battery unless it is quite hot. I've never seen the LEAF OEM battery hot enough to give such a low resting voltage wen full.
I believe this relates to charge voltage. I've always assumed that's due to increased internal resistance when cold. All the data I've seen on open circuit resting voltage is that it goes down with colder Temps.

For example, here's the charts from batteryfaq.org:

temp-comp-01.jpg


temp-comp-03.jpg


Agreed, it would be hard to get cold enough to get resting voltage of 12.6V on an AGM. Maybe less so with the flooded.

Rob
 
miscrms said:
I believe this relates to charge voltage. I've always assumed that's due to increased internal resistance when cold. All the data I've seen on open circuit resting voltage is that it goes down with colder Temps.
Thanks! I stand corrected.

Still, I stand by my conclusions for the graph above. The 12.9V value at 90% charge is the nominal value and I have seen significantly higher voltages on AGMs depending on the unit and SOC, including the 13.25V shown above. Some AGMs I have will sit at 12.9V while others will sit at 13.15.
 
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