Brake module or battery?

I bought my 2016 Leaf back in May. Had a trouble free summer and fall. In the last few weeks since the weather turned cold I have had the same issue twice. In both cases I had been driving using accessories, heater, wipers, lights. Parked, turned car off, returned shortly and when starting got warning lights, brake and red main warning light. Had the green "go" but car would not shift out of park. Brake pedal went to floor. In the first instance I was able, after several attempts, to get the car into gear at which point the brakes required a lot of pressure but did eventually work. I checked, and the brake fluid was low, at the min mark. Topped it up and still initially had warning lights/poor pedal response, but lights went out when I started driving and brakes went back to normal. Had it checked at the dealer, no problem with braking system. The second incident was this week. I had been driving with heater, heated steering, heated seats, and radio on, stopped to pick up my mail, and when I got back in the car and turned it on I had a repeat of the first experience. Got out, checked brake fluid, it was fine. Walked around the car a couple of times, got back in, started up, all was normal. Taking it to the dealer tomorrow, but my dealer doesn't have a lot of Leaf experience so would like to get some feedback on this forum. I'm hoping it's a battery issue, less expensive! What say you?

What's the voltage of the 12 volt battery when in this state and/or after the car has sat overnight or longer?

cwerdna said:

What's the voltage of the 12 volt battery when in this state and/or after the car has sat overnight or longer?

Click to expand...

Don't know. Haven't hunted in the basement for my late husband's old multimeter, but I did pop a battery tender on it this morning and it didn't take long to go green. However, I charged the car after the incident, so probably got topped up then, and of course if the battery is weak that might only be apparent under load. My thinking is that when I turn on, the demand on the battery may be taking the voltage down and affecting the electronic brake module. Disconcerting, to say the least! I am new to EVs and hadn't thought much about the way the brakes work on them, but from reading this and other forums I am thinking there is a potential major safety issue there....

It certainly sounds like a weak 12 volt battery, but you'll have to get the battery tested to be sure. Most auto parts stores will do a capacity test on them in the parking lot. In the meantime, shut off all 12 volt accessories except for the fan/blower a minute or two before turning the car off, but leave the blower on Low, as this tends to prod the car into charging the accessory battery. Top it off with the maintainer at least weekly, and more often if possible. If the warning lights and other symptoms stay away, then you have your answer. If they don't, then that battery test is next. It's a little early for it to be dying of old age, but if it got run near dead a few times, that damages lead-acid batteries. If you need a new one, get a higher capacity AGM lead-acid battery. The configuration you need is 51R. They run $150-$300.

LeftieBiker said:

It certainly sounds like a weak 12 volt battery, but you'll have to get the battery tested to be sure. Most auto parts stores will do a capacity test on them in the parking lot. In the meantime, shut off all 12 volt accessories except for the fan/blower a minute or two before turning the car off,

Click to expand...

Thanks for your reply. I always do this with my ACE vehicles, as my father taught me way back when. For what it's worth, I just got rid of a 2006 Tucson in May that had the original battery in it, and my 2011 Elantra has its original battery (and over 200,000 kms on it) as well, so I do swear by doing that but didn't think I needed to in an EV. I am taking the Leaf to the dealer in the morning so hopefully they will test the battery and read any codes. I'm not quite up to Leaf Spy yet...

Just keep in mind that one slight difference: you want to leave the climate control on before you shut the car off, to encourage the car to charge the accessory battery. And yes, it's pretty sad that we have to do this song and dance with an "evolved" vehicle like an EV.

LeftieBiker said:

Just keep in mind that one slight difference: you want to leave the climate control on before you shut the car off, to encourage the car to charge the accessory battery. And yes, it's pretty sad that we have to do this song and dance with an "evolved" vehicle like an EV.

Click to expand...

LeftieBiker, I don't understand what this will do to make a difference--could you explain?.

Eeeefarm, Your description of the brakes and warning lights really fits my experiences with both 2011 and 2015 Leafs when the original 12V batteries became weak. When the 12V battery is too low, some of the various control (computer) modules fail to initialize correctly when the car is started and some things such as the brake power assist fail to work. When the car is in ready mode, the DC-DC converter charges the 12V battery and then all the systems will work correctly if you turn the car off and back on. I replaced the original batteries in those cars with deep cycle AGM sealed batteries and will do the same when the battery in the 2019 shows the first signs of weakness.

Thanks, Gerry. From the reading I have been doing that is the conclusion I have come to, and hope it is correct. I live in a small town and there are not many EVs here, so I am guessing the local Nissan dealer doesn't have a lot of experience with them, and I have been trying to diagnose my problem to hopefully get them looking in the right direction. I get beyond my comfort level quite quickly with DIY solutions, as my late husband used to deal with the hardware, but I try to keep up with the technology as well as I can. Understanding the problem is the fastest way to a solution!

It's your call but personally, I would spend $100 to buy a new 12V battery, charge it, install it in the LEAF, then see if that resolves the issue. The Nissan dealer will charge you at least $200 just to look at it, then recommend hours of diagnostic work to figure out what's wrong (and likely recommend a replacement 12V battery).

alozzy said:

It's your call but personally, I would spend $100 to buy a new 12V battery, charge it, install it in the LEAF, then see if that resolves the issue. The Nissan dealer will charge you at least $200 just to look at it, then recommend hours of diagnostic work to figure out what's wrong (and likely recommend a replacement 12V battery).

Click to expand...

Replacing the battery myself is out of my comfort zone, but I suppose I could take the car to Canadian Tire and let them do it. Unfortunately I don't have anyone that can do this for me.

Since your car is beyond the 3-year, 36,000-mile bumper-to-bumper warranty, the dealer will charge diagnostic fees and then charge an excessive price for a mediocre 12V battery so I also recommend that you take it to an independent shop you trust and have a new battery installed. An AGM deep cycle battery would be the best choice, but they do cost a bit more (still less than Nissan dealer cost for a cheap battery). Then drive the car (or leave it parked in ready mode) for at least 30 minutes to make sure the new battery is reasonably well charged. The new battery should be fully charged the next time you charge the car overnight.

I am truly sorry that you lost your "in-house" mechanic and wish you well.

Thanks, Gerry. I appreciate your advice and kind words.

GerryAZ said:

Since your car is beyond the 3-year, 36,000-mile bumper-to-bumper warranty, the dealer will charge diagnostic fees and then charge an excessive price for a mediocre 12V battery so I also recommend that you take it to an independent shop you trust and have a new battery installed.

Click to expand...

I agree. When the replacement "84 month" Nissan 12 volt replacement I received bit the dust outside the portion of the warranty where it was fully covered, it was more $ to pay Nissan to install another one than to buy one from Costco and DIY.

I mentioned that at https://mynissanleaf.com/viewtopic.php?p=572068#p572068.

The first one on my used '13 Leaf (built 5/2013) but the dust in around Oct 2015 and was totally covered by the 3 year/36K warranty. The replacement I got is what failed later than I liked in Nov 2019.

LeftieBiker, I don't understand what this will do to make a difference--could you explain?.

Click to expand...

Anecdotal evidence suggests that the car charges the 12 volt battery more aggressively when the climate control is on. Probably just running the HVAC blower triggers it. It has also been suggested that running the wipers alone will do the same, but when I tested that theory the results were inconclusive.*

* It has also been suggested that the dim high beams on the Gen I Leaf are the result of too-low system voltage: 12.x volts instead of the more typical 13.x volts of a running ICE vehicle. So I tried turning the wipers on with the high beams already on, on a very dark road. There was no noticeable improvement in headlight brightness...

LeftieBiker said:

It has also been suggested that running the wipers alone will do the same, but when I tested that theory the results were inconclusive.*

Click to expand...

I can confirm when looking at the 12 volt bus voltage in LeafSpy that when the car's in READY mode, when you activate the wipers, even for just a single wipe, the 12 volt bus voltage jumps (IIRC to past 14 volts) and stays elevated for awhile before it falls back to what it was before. It seems to happen every time a wipe occurs. This is why we believe 12 volt batteries on Leafs last longer in rainy areas than where it doesn't rain much.

Even better would be rainy areas and '11 to '17 Leaf SL parked outside in the sun. Those cars have the tiny solar panel on the rear spoiler.

LeftieBiker said:

LeftieBiker, I don't understand what this will do to make a difference--could you explain?.

Click to expand...

Anecdotal evidence suggests that the car charges the 12 volt battery more aggressively when the climate control is on. Probably just running the HVAC blower triggers it. It has also been suggested that running the wipers alone will do the same, but when I tested that theory the results were inconclusive.*

* It has also been suggested that the dim high beams on the Gen I Leaf are the result of too-low system voltage: 12.x volts instead of the more typical 13.x volts of a running ICE vehicle. So I tried turning the wipers on with the high beams already on, on a very dark road. There was no noticeable improvement in headlight brightness...

Click to expand...

You're not going to notice a headlight brightness change with just a volt to 1.5 volts change in battery voltage.
Order a cigar lighter voltmeter to do your testing and evaluation;
https://www.amazon.com/LIHAN-Charger-Display-Voltage-Compatible/dp/B01JA627KU/ref=sr_1_5?crid=2XYG49ACZI1U7&dchild=1&keywords=cigar+lighter+voltage+meter&qid=1608259048&sprefix=Cigar+vol%2Caps%2C220&sr=8-5

You're not going to notice a headlight brightness change with just a volt to 1.5 volts change in battery voltage.

Click to expand...

I should have if the dim high beams were the result of the system voltage being 1-2 volts lower than the headlight bulb manufacturer assumed, and if activating the wipers raised the system voltage by 1.5 volts. I didn't know which theory I was collecting evidence against, though, which I why I wrote "inconclusive."

I never noticed it on the 2011 because I did not monitor the 12V system while driving, but the 2015 and 2019 do run the system at 14V with wipers on (and for a little while after turning them off). I have not noticed the same voltage rise with just HVAC use (which is why I asked for your explanation).

eeeefarm said:

alozzy said:

It's your call but personally, I would spend $100 to buy a new 12V battery, charge it, install it in the LEAF, then see if that resolves the issue. The Nissan dealer will charge you at least $200 just to look at it, then recommend hours of diagnostic work to figure out what's wrong (and likely recommend a replacement 12V battery).

Click to expand...

Replacing the battery myself is out of my comfort zone, but I suppose I could take the car to Canadian Tire and let them do it. Unfortunately I don't have anyone that can do this for me.

Click to expand...

If you are in the Vancouver area, I might be able to help you with installing the 12V battery for you. I just did the same on my own LEAF, didn't take very long.

alozzy said:

If you are in the Vancouver area, I might be able to help you with installing the 12V battery for you. I just did the same on my own LEAF, didn't take very long.

Click to expand...

Thanks so much for the kind offer, but unfortunately I am in Ontario. I know basically how to do the job, but as I said, out of my comfort zone.