Solutions to 12 Volt Batteries and Chargers Posted Here

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69800

Well-known member
Joined
Dec 30, 2011
Messages
173
Location
North Idaho
Because of all of the thread scattered around about the 12v battery problems, I have decide to start a thread on what we have come up with for solutions. I personal am doing a lot of testing with a data logger and will be putting the info and results here for all to see. I have graphed the Leafs 12 volt battery behavior over time as well as 3 different charges that I use. I will start with the demonstrating how the 12v battery is always in a continual state of being slowly discharged. RegGuheert's Posts have been very valuable and I will start with his demonstration and add my own as to this problem. Later I will add my graphs of how the Battery Tender Junior works as well as the Battery Tender Plus and the CTEK 7002. I will also put my choice of replacement battery and why I chose it. Here we go.

I will start with RegGuheert's graph of 22 days





Next I will show you my car on just on overnite session showing the car sleeping then the traction battery gets charge followed by the car going back to sleep waiting for its morning drive





And Finally here below is a 48 hour shot starting with a one time Battery Tender charge on Sunday nite followed by 2 days of normal use.





On my next Post I will show the data logger results of my 3 different chargers and the one I picked and why
 
Here is a comparison of the algorithm for the Battery Tender Jr (750ma) and the Battery Tender Plus (1.5amp). The Tender Jr is super for keeping a float charge on batteries. I use them on all of my mowers, 4 wheelers and motorcycles. However I personally think its absorption phase is a little to short for giving a battery a nice deep charge. Now if you used a regular charger on the battery first and then used Tender Jr for keeping it charged that will do. Or if you used it on the Leaf every day it would probably be fine.








For around the same money you can get the Battery Tender PLUS which is 1.5 amp and has a much longer absorption time. Not only that but it is temperature compensated so when the battery is cold it will give it the extra voltage it needs. For a once a week leaf recharge (which is what I prefer to do) this is my first choice. Also if you decide on an AGM battery in the future it was actually designed to handle the AGM batteries need for a longer absorption time.




 
Here is a view of the Leaf plugged in for the nite waiting for an L2 charge which will begin around mid-nite. The Battery Tender Plus is also plugged in and turned on. As you can see the 2 charging sources work fine together.


 
Interesting results. I also really like the Battery Tender chargers. I have both as well as the larger 5 amp version. I assume the tender you have is one of the newer ones, I think they changed them again last year, I know they look slightly different as well. I didn't realize the tender didn't bulk as long, I will switch back to the Plus to charge the leaf.
 
What makes you think any of the cells are sulphated?

At what temperature are the batteries when you're logging the data?

Are you reporting open-circuit voltages or is the battery connected to the car?

Have you checked the specific gravity of any cells? (This is a much better indicator of state of charge than voltage...)
 
yes this was open circuit and the specific gravity was checked with an MISCO 7064VP Refractometer. There is no question about the condition of this battery. Battery was a 72 degrees but drifted down to about 60 by the end of the day in the road tests. My Snap-on Load bank shows a fail. The leaf simply does not keep its 12v battery charged. I will be putting in an Exide Edge AGM next weekend and repeat the test.
 
69800 said:
yes this was open circuit and the specific gravity was checked with an MISCO 7064VP Refractometer. There is no question about the condition of this battery. Battery was a 72 degrees but drifted down to about 60 by the end of the day in the road tests. My Snap-on Load bank shows a fail.
Thanks for the add'l info. Sounds like you've got a battery on the way out.
69800 said:
The leaf simply does not keep its 12v battery charged.
..."the" Leaf, "that" Leaf, a "select few" Leafs, or "all" Leafs?

It might be worthwhile to have the DC-DC checked/replaced (not just have the car checked for error codes, but to have the DC-DC actually tested and probably replaced. Otherwise the next battery will have a short life as well. (Yes, I realize you're talking about adding a charger, but treating the symptom should not be necessary if the root-cause is fixed.)
 
I think it might just be the 2011 2012 models. If you read all of the 12v posts seems most people are seeing low voltage from the converters. They put out a 14.5 charge for just a little while then drop to float voltage of 13.0 and stay there. I decided to use and AGM battery due to the fact the plates cannot sulphate due to the design. Plus with lower resistance the battery charge much faster being able to better take advantage of the short charge cycle the converter provides. 4 year full replacement warranty.





 
An AGM won't protect anyone from an insufficient charge. Sealed or not, lead will not give a long life if it's not completely charged.

If Nissan won't swap the DC-DC to bring it up to spec, I'd replace the battery with LiFePO4 - it prefers to be kept a bit low.
 
You are correct. No battery wants to be under charged. The advantage to AGM is the plates are covered so sulfation is less likely to occur. The battery still needs to be externally charged at least once a week. LifePO4 is a good option if you want to spend the money. I actually wish I could have found a nice gel battery that would fit. The Exide Gel in my diesel tractor is now 14 years old and I have never charged it. Some times it sits for months.
 
AndyH said:
...
It might be worthwhile to have the DC-DC checked/replaced (not just have the car checked for error codes, but to have the DC-DC actually tested and probably replaced. Otherwise the next battery will have a short life as well. (Yes, I realize you're talking about adding a charger, but treating the symptom should not be necessary if the root-cause is fixed.)

69800 said:
I think it might just be the 2011 2012 models. If you read all of the 12v posts seems most people are seeing low voltage from the converters. They put out a 14.5 charge for just a little while then drop to float voltage of 13.0 and stay there. ...
It would be better if Nissan would fix their 12V charging protocol, but people have been complaining about it for four years or more, and people have been complaining about the Prius 12V charging for much longer than that.

Apparently they do not plan to fix it.
Nothing to indicate it is just 2011 and 2012, the 2013 forward LEAFs are just as bad.

The only way to extend 12V life is with routine do it yourself charging.

Without that, some have died in very short time.
My first was replaced at no cost under the warranty at two years. A few people were lucky and got four years but that was atypical.

Voltage will not tell you the condition of the battery.
The only real test is like the Snap On load tester.

I think the AGM is the most cost effective choice for most people. May last 50% longer than lead acid, maybe double if you regularly charge it.

Lithium would be much better, but usually two or three times as many $.
 
I had issues last summer when we charged to 80% regularly and over the winter we charge to 100% regularly and I haven't have any issues with the 12v battery. I still use a battery tender 1.25 amp to top them off weekly and again when I am charging to 100% it tops off quickly, 30 minutes or less. When I charge to 80% it takes a few hours. I also have the 6kw charger so charging an average of 60 minutes at 80% and at least twice as long to charge to 100% due cell balancing at the end of the process. I believe the longer charge times gives the 12v battery a longer charge as well.

I wonder if folks with the 3.3kw on board charger have longer lasting 12v batteries since there is a longer charge time or if people are using only the 120vac EVSE it would charge for a long times as well.
 
^^^ Yes, I agree with your conclusion.
With the 6.0 kW on board charger and using the 2013 80% charge timer setting would leave your 12V with the lowest amount of charge.

Someone using only 120V emergency EVSE should have much better 12V battery average charge level.

But 12V condition also depends on persons driving practices and use of the vehicle.
Using the LEAF for long periods of time in Ready mode without driving will also help the charging of the 12V.
 
to make the weekly Battery Tender charging job easier a add a built in plug so that on Saturdays I plug both the car and tender in together for the nite.



 
For those of you who may be interested in a larger charger which can be used for small batteries or AGM batteries her is the CTEK 7002 7 amp charger. In the first algorithm it shows a normal charge pattern although if you leave it on longer the voltage will eventually drop to 13.2 float volts. In the second one you can see it can be used to recondition a battery (desulphate) however due to the short time it spends at 15.7 volts I do not know how well it works. It is not recommended to desulphate and AGM battery unless the manufacturer specifically recommends if and how to do it. I use the CTEK to keep the dual batteries in my diesel truck charged.





 
My smart has a maintenance-free FLA and today (about a month old and fresh from a 100% main-battery charge) it's sitting at 12.53V.

One could buy a single Leaf battery can from the hybrid parts place, mod it to put all four cells in series instead of the 2P2S config it's in normally, and replace the lead lump with a single can of lithium. (Or just use two Leaf cans in series - it'll still be smaller and lighter than the lead-acid battery, will have more capacity, and will probably last longer than the traction battery.)

As I've got a bunch of 12Ah LiFePo4 and various BMS bits and pieces on the bench, I'll replace the 42Ah lump-o-lead with lithium. I don't want to kludge the car, and the weight savings will be good for range.
 
Is there any value in measuring the voltage of any lead battery when it's still connected to the car? It's my understanding that those data points don't really mean anything. You need to measure the specific gravity or disconnect it and let it actually rest unloaded to get a meaningful SOC.

FWIW my 2011 will be 4 years in June and havent he any problems yet. It's been a long time since I've tested it on a digital load tester though.
 
QueenBee said:
Is there any value in measuring the voltage of any lead battery when it's still connected to the car? It's my understanding that those data points don't really mean anything. You need to measure the specific gravity or disconnect it and let it actually rest unloaded to get a meaningful SOC.

FWIW my 2011 will be 4 years in June and havent he any problems yet. It's been a long time since I've tested it on a digital load tester though.
Yeah, it's already been reported as being open-circuit. That was my first question.
 
AndyH said:
QueenBee said:
Is there any value in measuring the voltage of any lead battery when it's still connected to the car? It's my understanding that those data points don't really mean anything. You need to measure the specific gravity or disconnect it and let it actually rest unloaded to get a meaningful SOC.

FWIW my 2011 will be 4 years in June and havent he any problems yet. It's been a long time since I've tested it on a digital load tester though.
Yeah, it's already been reported as being open-circuit. That was my first question.

Maybe I missed something but how do you measure the open circuit voltage while th battery is being charged/connected to the car like all the graphs in the original posts?
 
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