Scaramanga
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Leaf Number: 308884
Location: Tacoma, WA

Re: LEAF's 12V battery behaviors - and why they go bad

Mon May 15, 2017 8:13 am

lorenfb wrote:
And your insightful input with 33 years auto "exp"?


It's a fair question. I put 33 years of mechanical "experience" in my signature instead of "mechanic" because nobody pays me to do it anymore. I'm an IT program manager, and although I have worked professionally on VW's, Volvo's and Mazda's years ago, I'm more of a really good shade tree mechanic now. Since I was 18 I've spent most weekends fixing a project car, or a friends car. Engine rebuilds, transmission rebuilds & fixes, carbs & fuel injection, suspensions, electrical, body & paint. All bone stock mind you, never really go-fast stuff, mostly un-do what the last fool did, or just resurrect an old car from where the last owner just gave up. I stopped making my living as a mechanic because I liked to work more slowly and carefully than my bosses wanted to run their shop, which is fine. Anyway, so I think I know significantly more than the average enthusiast about making internal combustion vehicles go, but I'm admittedly an EV newb, which is exciting, something new to learn.

So I will say that I take a more broad brush approach to automotive charging systems than the group here does from what I've seen. Partly that's because of my experience is with traditional battery / alternator systems that you could fix with an ohm meter and a load test. ICE charging systems are just not that complicated. The situation the groups is dealing with here is decidedly more nuanced.

Here's what I think I know and some of what I think we should do:

0) I don't pretend to know everything there is to know about this problem. Somebody might, but I haven't talked to them yet.

1) Any 12v car battery that shows a voltage of 12.6v at 'rest' is charged. That's just math.

2) Any value above that (13.0v - 14.4) represents a battery that is charging or has just finished doing do, cooling down, what have you. On an ICE car, I would stop looking here and go find something cold to drink, watch Alaska State Troopers, fuss about my tires, whatever.

3) Battery sulfation is a function of age (hundreds of charge cycles) OR insufficient charging after discharge. When freshly discharged, a healthy 4 - 6 amp charging cycle will 'blow off' battery sulfation, sometimes you can even see the Pb crystals floating in the electrolyte before they are absorbed. On an ICE car, if I couldnt' get a battery to draw about 6 amps on a charger, and the battery was more than 3 years old, I would stop here and throw the thing in my trunk and buy a new one. Yes, I've been able to resurrect old, sulfated batteries before but it never really turned out to be as good as just getting a new one.

4) 90% of the time on an ICE car, your battery charging problem is/was a bad ground somewhere at the body / head / engine block / starter. It's magic how if you took a brass brush to all of those places, cleaned off all the crud, everything would start to work, charged battery, brighter lights, etc. I'm not saying that's what's happenening here, but because we don't have an alternator to fiddle with, but it's worth a look. Volvo's are particularly susceptible to crusty grounds, I don't know about Nissans.

5) We ought admit that this charging system is 'just different' than any ICE car we've ever owned. We can't touch the alternator and are thus vexed. If there was an alternator available when the car was at rest that we could stick an ohm meter on, we wouldn't be having this discussion I think, and everyone would be happier and drinking something cold, and watching Alaska State Troopers.

6) The group is spending a lot of time arguing & being personally hurt / insulted about battery chemistry, I don't think this is particularly useful. I think it'd probably be better to:
a) Get / Make / Steal whatever tool the dealer uses to test a Leaf charging system, if their is such a thing that isn't just an ohm meter and load tester.
b) Read the LEAF 12v charging system manual cover to cover.
c) Empirically test hundreds of charging systems / batteries as a group in a central location / database, gather TONS of facts and data.
d) Compare notes and discuss rationally.

7) Admit we may not arrive a common solution, and that's okay. Each of us has a different battery (brand, age, quality, level of abuse, ambient temperature environment, etc.). There's just too many variables in my opinion. Fuel injection is fairly finite if your injectors are clean. Bosch Motronic EFI used in tons of European makes will quite literally tell you precisely whats wrong with it if you listen, and if you can follow directions, any monkey can fix it. Charging systems are decidedly not this way because they involve a chemical reaction which confuses people and is why people needlessly throw alternators and batteries at cars when most of the time the problem lies elsewhere.

8) Our group seems to have a certain fury / rage about all of this that I think is misplaced. I get it that batteries are expensive (like 2x what they cost 10 years ago) and that this is marginally a safety issue and certainly annoying. But it's a battery. My dime is use the warranty, and then buy good enough batteries that you can keep using the warranty if you need to, because the charging system is effectively (AFAIK) what it is. If enough people report the problem to Nissan, something will probably change, presumably in the charging system firmware.

9) This is not personal. Full Stop.

TF
2016 SL Premium - Gunmetal Grey, built 2/2016
2014 S w/ QC - Cayenne Red, built 1/2014
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LeftieBiker
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Re: LEAF's 12V battery behaviors - and why they go bad

Mon May 15, 2017 1:04 pm

ICE batteries don't die while you're driving, and take braking power with them. The issue is not primarily the cost of the batteries, but the loss of faith that the car will A: start, and B: get you where you're going safely.

I and most others here tell folks that if the battery is below 12.6 volts (not at that voltage) that the battery isn't fully charged. And that's true. Below 12.5 volts and it's chronically undercharged.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

Scaramanga
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Joined: Fri Apr 28, 2017 9:31 pm
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Leaf Number: 308884
Location: Tacoma, WA

Re: LEAF's 12V battery behaviors - and why they go bad

Mon May 15, 2017 7:26 pm

LeftieBiker wrote:ICE batteries don't die while you're driving, and take braking power with them.


Understood, so the brake booster having no source of vacuum presumably runs on 12v, that's certainly unpleasant and likely un-nerving to an inexperienced driver if that's what's going on. There's a ton of posts in this thread so forgive me I haven't read that particular detail. I have this question: When the 12v battery goes flat while driving, what happens to brake power, does it just fail to no boost as if the motor on an ICE car's motor quits running while the vehicle is moving? I'm assuming the ABS pump wont work either. I have to look at the circuit design, I'm just curious why Nissan wouldn't have a 400v DC to 14v DC converter that would boost the 12v system immediately if it detects a low voltage in the 12v battery just like the voltage regulator on a DC generator cycles on/off charging the battery.

Makes me wonder what the common thread is here, we need data.
2016 SL Premium - Gunmetal Grey, built 2/2016
2014 S w/ QC - Cayenne Red, built 1/2014
EVSE: ChargePoint 25 32A Plug-In w/ 18' Cord
ELM 327 / LeafSpy Pro
'06 Sentra Compact Spare / Jack
Renault Tow Hook

2016 Murano SL AWD
VW / Audi / Volvo ex-aficionado

LeftieBiker
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Location: Upstate New York, US

Re: LEAF's 12V battery behaviors - and why they go bad

Mon May 15, 2017 8:10 pm

IIRC, there is a supercapacitor in the braking system that can briefly power the brake booster, but not for long. I know the Gen I Leaf had one, but I'm not 100% certain it was retained in the Gen 1.2(?) from 2013 on.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

GerryAZ
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Re: LEAF's 12V battery behaviors - and why they go bad

Tue May 16, 2017 4:02 am

The DC-DC converter is capable of delivering well over 100 amperes at 12 to 15 volts and will easily power the car while recharging a depleted 12-volt battery after jump starting (at least my 2011 did and my 2015 does). There was one case reported on the forum of a car that shut down while driving apparently due to failure of the 12-volt battery. The brakes will still work without power assist, but the pedal is near the floor and requires excessive force much like a gas engine car without vacuum assist. For a driver who has never experienced this before, it could seem like the pedal has gone to the floor and that there are no brakes. The steering wheel becomes difficult to turn without electric assist, but the car can still be controlled.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

VitaminJ
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Re: LEAF's 12V battery behaviors - and why they go bad

Tue May 16, 2017 8:07 am

Scaramanga wrote:
LeftieBiker wrote:ICE batteries don't die while you're driving, and take braking power with them.


Understood, so the brake booster having no source of vacuum presumably runs on 12v, that's certainly unpleasant and likely un-nerving to an inexperienced driver if that's what's going on. There's a ton of posts in this thread so forgive me I haven't read that particular detail.

No, it's worse than that. In an ICE car if the engine shuts off or the electrical system fails, your foot can still create hydraulic pressure in the lines and you stop. In the Leaf, as far as I can tell, when the 12v system stops providing it enough juice, your foot CANNOT create hydraulic pressure in the lines no matter how hard you press.

This thread was written by a member who rear-ended another car when his 12v system took a dump: viewtopic.php?f=30&t=23730&
2013 Ocean Blue SV w/ QC and LED
- +0.2 mi/kwh Aeromods
- Leaf Box
- 2lb 5Ah LiFe 12v battery

LeftieBiker
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Re: LEAF's 12V battery behaviors - and why they go bad

Tue May 16, 2017 12:06 pm

Gerryaz and VitaminJ may both be right. I remember big American cars with vacuum brake boosters, and if you tried to brake with the engine off, (after a couple of seconds if it was running) the brakes would technically work, but the pedal effort was so high it would be easy to crash the car at speed. At a stop it would be so hard to turn the wheels that they might as well not be steerable.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

taloyd
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Re: LEAF's 12V battery behaviors - and why they go bad

Wed May 17, 2017 5:01 pm

Cross-posting myself as it's relevant:

viewtopic.php?p=494786#p494786

Here's the full post:

From the above, what i'm hearing is that people did not have 12V battery problems before performing the 2G --> 3G telematics upgrade but do have 12V problems after.

I know that from my experience, with 65k miles on the car, my problems began within 2 days of having the telematics upgrade done. I've been through 5 batteries since the 'upgrade' was performed in December, and regret it deeply.

This leads me to believe that the telematics unit plays a part in the 12V battery. Perhaps the mediocre charging algorithm was adequate enough to cope with the previous generation TCU but not with the likely-greater-power-draw of the newer generation. That seems reasonable to me (thanks, Occam!) but I could be wrong (thanks Hickam!).

In either case, if these problems don't resolve, I'm moving away from a Leaf, likely towards a Hyundai IONIQ with their very appealing (to a 20k/year driver) unlimited mileage lease.

Picking the car up from the dealer today, after two weeks, 3rd time it's there since the telematics upgrade. They didn't identify or thereby resolve the problem, but assured me that "it turned on for 3 days in a row" so I'm very comforted and going to test drive a Hyundai in the next week or two.

Best,
Tal
2017 Bolt LT (w/ DCQC)
Purchased 2017/07
MON DIEU - what a treat!

2013 Leaf SV
Purchased (not leased!) 2013/09
59,860 - lost first bar. :-(

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RegGuheert
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Re: LEAF's 12V battery behaviors - and why they go bad

Wed May 17, 2017 5:39 pm

taloyd wrote:From the above, what i'm hearing is that people did not have 12V battery problems before performing the 2G --> 3G telematics upgrade but do have 12V problems after.
O.K. That makes me glad that my Nissan dealer dropped the ball TWICE when I have asked them to perform the upgrade. Frankly, at this point we are used to using the car without Carwings.
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

lorenfb
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Re: LEAF's 12V battery behaviors - and why they go bad

Wed May 17, 2017 6:36 pm

taloyd wrote:Cross-posting myself as it's relevant:

viewtopic.php?p=494786#p494786

Here's the full post:

From the above, what i'm hearing is that people did not have 12V battery problems before performing the 2G --> 3G telematics upgrade but do have 12V problems after.

I know that from my experience, with 65k miles on the car, my problems began within 2 days of having the telematics upgrade done. I've been through 5 batteries since the 'upgrade' was performed in December, and regret it deeply.

This leads me to believe that the telematics unit plays a part in the 12V battery. Perhaps the mediocre charging algorithm was adequate enough to cope with the previous generation TCU but not with the likely-greater-power-draw of the newer generation. That seems reasonable to me (thanks, Occam!) but I could be wrong (thanks Hickam!).

In either case, if these problems don't resolve, I'm moving away from a Leaf, likely towards a Hyundai IONIQ with their very appealing (to a 20k/year driver) unlimited mileage lease.

Picking the car up from the dealer today, after two weeks, 3rd time it's there since the telematics upgrade. They didn't identify or thereby resolve the problem, but assured me that "it turned on for 3 days in a row" so I'm very comforted and going to test drive a Hyundai in the next week or two.

Best,
Tal


1. It's very very unlikely that the TCU's active current drain is such that the charging system can't compensate,
i.e. the active TCU current is most likely less than 1-2 amps. If the standby current, when the vehicle is off and
when the TCU should be in its "sleep" mode is never entered, that could result is a dead 12V battery, i.e. a function
of the active current and time between each "startup" and driving. Those "motivated" owners could attempt
to measure the active current drain of the TCU, i.e. the "delta" Leaf current @ the 12V battery. Also, the Leaf
"sleep" current should be measured, typically less that 100ma (mine about 60ma).
2. If the TCU "hangs" in a mode when trying to connect and the vehicle is subsequently turned-off, the TCU may
fail to enter its "sleep" mode. This could be a firmware problem. I personally don't access the TCU remotely,
i.e. I only use it to update the charging stations. I know when the TCU completes it operation, so using the
remote access mode could be problematic. My TCU failed to connect once after using Carwings, necessitating
a disconnecting of the 12V battery to reset the TCU. Resetting of the TCU's fault codes failed to re-establish
the TCU's functionality. I have avoided using Carwings since. Those using the remote function (Carwings)
need to correlate the TCU's operation and their dead battery.

Bottom Line: Without more meaningful data, no valid conclusions can be arrived at.

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