Solutions to 12 Volt Batteries and Chargers Posted Here

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erichz said:
Preferably one that doesn't involve hooking up to a battery tender every week or so?

That's not necessary if the electrical system is functioning properly, e.g. no controller failing to enter its
"sleep mode" (low current draw) or something causing a current drain greater than 50 - 80 milli-amps.
There's been speculations of an inadequately designed Leaf 12V battery charging system, but data to
fully corroborate that have only been anecdotal.
 
There's been speculations of an inadequately designed Leaf 12V battery charging system, but data to fully corroborate that have only been anecdotal

You mean as opposed to signed confessions by Nissan engineers? There is plenty of data to support the "bad algorithm" theory. The only real uncertainties are the exact driving patterns that make the issue worse, or minimize problems, and whether using a larger SLA battery solves the problem or just helps in some situations. The evidence seems to suggest that lots of short trips, especially with heavy 12 volt accessory use, drive the battery's SOC down, while longer trips with light to moderate accessory use tend to keep it at least 75% charged. This likely being the case, then using a higher capacity deep cycle SLA battery should alleviate the problem, except in cases where there is a phantom drain in the system. Even then I'd want to charge that battery externally at least once a month.
 
LeftieBiker said:
There's been speculations of an inadequately designed Leaf 12V battery charging system, but data to fully corroborate that have only been anecdotal

There is plenty of data to support the "bad algorithm" theory..

Really? I've yet to see any exhaustive study to corroborate that. Generally, we find posts that intimidate
new Leaf drivers to a potential unfounded Leaf problem before any analysis is done on the vehicle with
12V battery problems, e.g. determining the sleep current draw, making sure no courtesy lights remain
"on", or that no OBDII plug-in devices remain "on".

Again, anecdotal data doesn't qualify!
 
Isn't most automotive reliability data anecdotal in nature? I feel like once you've heard enough reports of a problem, you can start to believe it's a defect. From what I've seen, we can safely assume 12V battery longevity is an issue on the Leaf compared to ICE vehicles.

Anyway, I'm going to monitor my current battery. If it dies again or looks like it isn't being charged properly, I'll replace it, perhaps with an AGM, or perhaps just the cheapest thing I can find. In the meantime I'm investing in a jump box. I don't think Lithium 12V replacement is the answer in my climate.
 
erichz said:
My 12V battery up and died on me yesterday. .......Snip..... but do we have a long-term solution? Preferably one that doesn't involve hooking up to a battery tender every week or so?
That's my long-term solution (I'll reach 5 yr this August, hopefully on the original 12V battery). I put it on a tender once or twice a week, sometimes more, but I'm not super worried about it. Most times it takes 4+ hr to reach full. My driving is basically all in-town, 35 mph and less than 5 mi one-way. Interestingly, I put the charger on my 1990's ICE battery which I hadn't driven in a few months, and it was FINE, filling in less than 15 min. So definitely, the older cars with fewer (almost no) electronics don't drain down the 12V battery like the newer cars.
 
The thorough data taken by "69800" that started this thread shows that (his) Leaf's charging profile is VERY inadequate for proper charging of any lead-acid technology battery. The most robust deep cycle off-grid (solar application) batteries would likely fail quickly with this charging profile (maybe less than a year of daily cycling) - well maybe not fork lift batteries :lol:

IMHO - the extremely light duty that the Leaf's battery is exposed to, combined with just barely keeping the charge voltage (there is no staged charging profile really) above sulfation level (70% SOC), combined with trying to minimize all continuous energy draws - maybe the Nissan Engineers felt their design is a good compromise? Also, It seems the OEM battery is a very high quality "CCA" type battery of which they certainly are familiar!

However, to design in a failure mode that is just a matter of time - and is often unannounced - is very problematic.
 
Marktm said:
The thorough data taken by "69800" that started this thread shows that (his) Leaf's charging profile is VERY inadequate for proper charging of any lead-acid technology battery.

However, to design in a failure mode that is just a matter of time - and is often unannounced - is very problematic.

A sampling data on one vehicle in a population, hardly justifies an extrapolation to the whole population
and a robust conclusion!
 
About this argument on whether the Leaf is bad to 12V batteries - It's all relative.

There is certainty that the Leaf charges the 12V battery.
There is certainty that the Leaf does not charge the 12V battery for optimum battery life, far from it. This is easy to determine by parking the Leaf and measuring battery voltage over time. You'll see it drop into the range where 12V batteries are known to start seriously sulfating.

There is also lots of anecdotal evidence about people who have had Leaf 12V batteries fail in <3 years.
There is also lots of anecdotal evidence that a bad Leaf 12V battery will lead to problems.

To all Leaf owners, my personal advice is either:
1) replace the 12V battery every 3 years, or
2) use an external battery charger like the Battery Tender Plus.

Your mileage may vary.

Bob
 
lorenfb said:
A sampling data on one vehicle in a population, hardly justifies an extrapolation to the whole population
and a robust conclusion!

All the similar data that I've taken with my Leaf confirms the extensive data from 69800 - never seen voltages on my battery that is appropriate for proper charging and most often well below voltages that prevent sulfation, except for a very brief instant. I agree that a Leaf dying and leaving someone stranded in traffic is anecdotal to the charging profile, but why take that chance?
 
Loren doesn't seem to understand that virtually everyone who uses a battery maintainer gets to see, via the LED indicator on the unit, whether the car's accessory battery is full (almost never!) near full (rarely) or requires significant charging (usually) when it gets connected. We can also, if we check back regularly, see how long it takes to top off the battery. Knowing the output of the maintainer gives us, more or less, how many AHs had to be added to the battery. That is how I know that short trips with heavy accessory use drain the 12 volt battery much more than long trips with light accessory use. These observations have also been confirmed by others. The idea that all this is based on the behavior of one Leaf is very mistaken.
 
Try turning "on" the wipers while monitoring the battery voltage. This is one of the undiscovered charging
modes that the Leaf enters into, i.e. mentioned up-thread that anecdotal data takers failed to find,
where it charges greater than 14 volts. What other modes exist in the Leaf's charging algorithm that have
been overlooked where the Leaf charges greater than the 13 volts normally observed?
 
lorenfb said:
Try turning "on" the wipers while monitoring the battery voltage. This is one of the undiscovered charging
modes that the Leaf enters into, i.e. mentioned up-thread that anecdotal data takers failed to find,
where it charges greater than 14 volts. What other modes exist in the Leaf's charging algorithm that have
been overlooked where the Leaf charges greater than the 13 volts normally observed?

There may well be others, but when you stop the car and the battery is 2+ AH down from full, the car isn't adequately charging the accessory battery.

How about a little input from others who use battery maintainers? How often does the maintainer go into full charge mode (usually a solid red light) when you connect it, how often into finish charge mode (flashing green or solid yellow) and how often do you connect the battery and it's either green (float) immediately, or within a minute or so?
 
LeftieBiker said:
How about a little input from others who use battery maintainers? How often does the maintainer go into full charge mode (usually a solid red light) when you connect it, how often into finish charge mode (flashing green or solid yellow) and how often do you connect the battery and it's either green (float) immediately, or within a minute or so?

I have left my battery charging on two - 1 amp chargers for over 24 hours and the red light was still on - and both were very warm. I was actually surprised as I was expecting them both to go to "maintenance" (flashing green, no red) in about 1/2 that time based on the battery size (~40 AH?) and estimated SOC (from settled voltage curve). The charge voltage was 13.5 +, but I had no way of determining if the Leaf had any substantial drain during this charging - should have disconnected it.
 
Before I swapped out my 12v battery I would charge every Friday night with a Deltran battery tender charging at 1.25 amps and rarely would it be blinking green (absorb) in the morning 8 hours after the start, often it would take 12+ hours to get to float. Sometimes I would charge mid week as well and then it was usually about 4-5 hours to absorb.

Now that I have swapped the stock 51R for a slightly larger 34N I still top it off every Friday but usually it starts absorbing in 10 to 15 minutes and floating in less than hour.

My theory is the Leaf charging pattern drops in to float way to soon for a smaller or weak battery, which also would explain why some people have no problem if they started with a "good" battery. But even if that is the case I agree that the Leaf under charges or defect charges the aux battery in some cases.
 
Marktm said:
The charge voltage was 13.5 +, but I had no way of determining if the Leaf had any substantial drain during this charging - should have disconnected it.

Right, one always needs to first check the standby current (drain) to be assured that there's no parasitic drain
(> 50 - 80 ma), e.g. the result of an ECU (controller) failing to enter its sleep mode. This is a very very common
problem with present day automotive electronics and its CAN bus technology that results in dead 12 volt
batteries. In some vehicles, it may take as long as ten minutes for all ECUs to enter their sleep mode,
thereby draining the battery with the vehicle being off. Remember, when you press the On/Off button
on the Leaf, the 12 volt battery power consumption isn't zero as was the case with non-electronically
controlled vehicles of the past.
 
Well, my 12v battery died again unexpectedly. I've now taken it to the dealership for testing to see if there's a slow drain somewhere, or (more likely) the battery itself is just not being charged sufficiently on shorter trips.
 
erichz said:
Well, my 12v battery died again unexpectedly. I've now taken it to the dealership for testing to see if there's a slow drain somewhere, or (more likely) the battery itself is just not being charged sufficiently on shorter trips.

Lost track - Is this the same battery that originally failed, or a replacement? If nothing is wrong with your Leaf's 12 volt system, I'd guess you have a bad cell in your battery - which should show up in the dealer's load test equipment.
 
Got the car back from the dealer with no resolution. Their tests turned up no problems with either the 12v or a parasitic drain after 4 days of looking.
 
erichz said:
Got the car back from the dealer with no resolution. Their tests turned up no problems with either the 12v or a parasitic drain after 4 days of looking.

Might want to take it to a trusted mechanic that has a battery load tester and explain what has happened. See if the battery is definitely OK.
 
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