Solutions to 12 Volt Batteries and Chargers Posted Here

[lorenfb]

A necessary diagnostic tool for those Leaf lead-acid battery "analytical researchers".

 

[DaveEV]

MOD NOTE: lorenfb, if you have nothing productive to add to the thread, please don't post. People are getting tired of it.

 

[RegGuheert]

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V>3C15D>12.57V>12.43V

Obviously the higher voltages seen yesterday were mostly surface charge, so not the SOC is back to where it was three (and five) days ago. It appears to be holding the voltage around 12.44V, but experience tells me it will continue lower before it stabilizes: down to around 12.25V.

 

[QueenBee]

A necessary diagnostic tool for those Leaf lead-acid battery "analytical researchers".

Anyone have any recommendations on a digital version of this for personal use?

I tried to measure the health of my battery by fulling charging it and then disconnecting it but it's very hard to go more than 12 hours and after just 12 hours between 60 and 50 degrees it was still at 12.72 volts which I believe is higher than expected for a 4 year old battery, correct?

So random question. Doesn't anyone else measure about 50 volts AC between either terminal of their battery tender and their buildings ground/neutral?

To try to clarify my previous point of why I think there are two related problems with LEAF charging. The issue being discussed at depth here is that when the DC->DC converter is on it's not using a charging algorithm which optimally charges the battery for highest longevity. The outcome of this being that someone who never experiences a dead battery will have a shorter battery life than is possible.

Then I think the second problem is that for whatever various reasons the algorithm which decides when to automatically come to life and charge the 12v battery does not achieve the requirement of not letting the 12 volt battery go dead. Even with the first problem this automatic process could and IMO should still keep the battery at the under charged state, not letting it ever go completely dead. As has been reported in many other threads this is not always the case. So LEAF owners who leave the car parked under various specific sets of conditions come back to find the 12v dead.

I don't think I have seen it mentioned but one resolution to this problem is there is a NTSB for I believe applie io just 2013s experiencing 12v battery issues with the remedy being a software update. Sorry I don't have this handy.

 

[RegGuheert]

Anyone have any recommendations on a digital version of this for personal use?

Harbor Freight has a digital meter which measures the impedance of your battery for $80: Digital Battery Analyzer. I don't have one, but the reviews are decent. It doesn't put a large load on the battery, but rather it measures impedance using a smaller load and a four-wire measurement technique. This should be fine for the LEAF since it typically does not have a large load on it.

I tried to measure the health of my battery by fulling charging it and then disconnecting it but it's very hard to go more than 12 hours and after just 12 hours between 60 and 50 degrees it was still at 12.72 volts which I believe is higher than expected for a 4 year old battery, correct?

I would expect a reading at least that high with a battery even seven years old in your climate (or mine).

Personally, I'm more interested in my battery's voltage in-situ, since that tells me how quickly the voltage (and, hence, the SOC) drops with the car loading it. As you can see from my measurements, my LEAF battery was at 12.78V after 24 hours, even though it was loaded by the LEAF. My reading may be higher than yours for a variety of reasons. Battery health could be one, but likely my battery was more fully charged when I took it off the charger (different charger). Also, batteries come from the factory with slight differences in chemistry and this shows up as slightly different battery voltages. Differences of 0.1V or more at the same SOC are not uncommon with new batteries of the same type.

So random question. Doesn't anyone else measure about 50 volts AC between either terminal of their battery tender and their buildings ground/neutral?

Yes. I measure ~64VAC from neutral or ground to either battery terminal of my BatteryMinder 1500. But both of my maintenance battery chargers are fully isolated between the AC input and the DC output. I expect the AC is due to the small capacitance of the transformer inducing the AC waveform on the outputs due to the extremely high impedance it sees. I don't think there is anything to worry about.

To try to clarify my previous point of why I think there are two related problems with LEAF charging. The issue being discussed at depth here is that when the DC->DC converter is on it's not using a charging algorithm which optimally charges the battery for highest longevity. The outcome of this being that someone who never experiences a dead battery will have a shorter battery life than is possible.

Agreed. That is my main grievance. I have no other vehicle which does not return home with the 12V battery fully charged.

Then I think the second problem is that for whatever various reasons the algorithm which decides when to automatically come to life and charge the 12v battery does not achieve the requirement of not letting the 12 volt battery go dead. Even with the first problem this automatic process could and IMO should still keep the battery at the under charged state, not letting it ever go completely dead. As has been reported in many other threads this is not always the case. So LEAF owners who leave the car parked under various specific sets of conditions come back to find the 12v dead.

Also agreed. This is more of a nice-to-have that EVs can offer because they have a zero-emissions on-board energy source.

What's frustrating about the LEAF is that it has EVERYTHING in place to allow it to fully maximize 12V battery life including a high performance, three-stage charger. It even has the feature to charge the 12V battery every five days in case the car is just sitting. But they seem to have missed three important facts about lead-acid batteries:

1) You simply cannot charge a lead-acid battery to full in a few minutes (or a few seconds). Hours are required.
2) You cannot charge a lead-acid battery to full using a 13.1V source.
3) If you do not FULLY recharge a lead-acid battery every few days (every day if it is very hot), then some of its capacity will be lost due to the hardening of the lead-sulfate which forms during the discharge reaction. This effect is cumulative and cannot be recovered using standard charging routines.

In other words, what separates the LEAF's 12V charger from being one of the best in the world is simply firmware. There is no reason why the 12V battery in the LEAF does not last LONGER than the battery in any ICE vehicle.

I don't think I have seen it mentioned but one resolution to this problem is there is a NTSB for I believe applie io just 2013s experiencing 12v battery issues with the remedy being a software update. Sorry I don't have this handy.

And this is a third issue being discussed in this thread, as there appears to be a firmware bug in the MY2013s and beyond which causes a load to be left on sometimes, draining the battery. If Nissan has a fix, that is great news!

I don't believe this last issue impacts MY2011/2012 owners. To my knowledge, the 12V battery in my LEAF has never been fully discharged.

I believe OP's main focus for this thread is on solutions. So far, I have seen several suggested:

1) Do nothing - Indeed, it appears for some driving patterns the LEAF's 12V charging system will keep the battery in decent-enough health to at least get to four years.
2) Intermittently recharge the LEAF's 12V battery using a maintenance charger - This is what I do. I'm very inconsistent about how often I charge the LEAF's battery.
3) Intermittently desulfate the LEAF's 12V battery using a desulfating charger - I also do this. Typically this is done while the LEAF is parked during vacation.
4) Replace the LEAF's 12V battery with a flooded deep-cycle battery - I'm not sure what's out there for this purpose, but this is a valid option.
5) Replace the LEAF's 12V battery with a sealed lead-acid (SLA) battery - This is the option that OP is reporting in this thread. One benefit of an absorbed glass mat (AGM) SLA battery is that the lead sulfate is held in place by the glass mat and it may be easier to break up using a desulfating charger (or even a normal charger). One interesting observation is that OP's AGM has a resting voltage when fully charged which is HIGHER than the 13.1V float voltage used by the LEAF. That means that if the battery is full then the LEAF will DISCHARGE this battery when operating in float mode. The float voltage probably corresponds to some SOC above 90% for OP's battery. (I suppose that is why my maintenance chargers use a float voltage of ~13.5V.)
6) Replace the LEAF's 12V battery with a Li-ion replacement - This is certainly the most expensive option, but perhaps the least fiddly. Li-ion batteries have a couple of benefits: First, it doesn't matter if you fully recharge them. In fact, it's best if you don't! Also, the algorithms in the LEAF would likely cause a Li-ion battery to maintain (or increase) the SOC with each cycle since the Li-ion battery can accept the charge quickly. Still, I wonder how long such batteries will last. There is a very wide range of Li-ion battery life out there depending on many factors. But so far, there have been no reports of any problems with them in the LEAF.

Did I miss any other suggestions?

 

[RegGuheert]

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V>3C15D>12.57V>12.43V>12.40V

I measured a couple hours early today, but likely the voltage is the same as it would be at 11:00AM (it typically doesn't change between about 9:00AM and 6:00PM due to the solar panel on the spoiler). So, after a full two weeks of typical usage in my household the battery voltage has dropped from 12.87V (very fully charged) to 12.40V. I'll estimate the SOC to be about 70% now.

Anyway, I plugged it in after taking the voltage reading and I timed how long the charger held the voltage above float. It went up to ~14.5V, as usual, and stayed there for a grand total of 35 seconds before dropping down to float. I guess it didn't think 12.40V was low enough or the fact that the battery hasn't been fully charged in two weeks was sufficient reason to warrant any further charging. :roll:

 

[TimLee]

...I guess it didn't think 12.40V was low enough or the fact that the battery hasn't been fully charged in two weeks was sufficient reason to warrant any further charging. :roll:

Which is why I postulate the algorithm it uses disregards voltage.
Primarily looks at net current drain since the last time it applied 14.5 volts.
Although it may also observe current when it applies 14.5V and also adjust duration based on that.

Would be an interesting test to fully charge the 12V battery, then disconnect it from the LEAF, substantially discharge it with external load, hook it back up, start the LEAF charging, and monitor what the DC to DC voltage and current flow to the 12V does.

The LEAF 12V charging may be a combination of net current it has monitored (which in this case would be zero, no monitored loss), and the current flow it observes when it applies 14.5 V.
With a substantially discharged 12V it would still see more current flow than with a fully charged 12V, so probably would still hold 14.5 for a long time.
But I haven't done the proposed test to confirm.

 

[RegGuheert]

Which is why I postulate the algorithm it uses disregards voltage.
Primarily looks at net current drain since the last time it applied 14.5 volts.

I agree it seems to be using an algorithm which is designed to replace some % of net charge lost (while ignoring the three important facts about 12V battery charging mentioned in my post above in response to QueenBee).

Would be an interesting test to fully charge the 12V battery, then disconnect it from the LEAF, substantially discharge it with external load, hook it back up, start the LEAF charging, and monitor what the DC to DC voltage and current flow to the 12V does.

That would be an interesting test! I may try that someday, but not before I continue my daily monitoring test to try to see if it ever decides to charge the battery up to full as a matter of course. In my previous test two years ago, it never did in three weeks of monitoring. But this time around, I KNOW my battery can hold the charge if it decides to do it.

The LEAF 12V charging may be a combination of net current it has monitored (which in this case would be zero, no monitored loss), and the current flow it observes when it applies 14.5 V.

Most modern chargers hold the voltage at 14.5V UNTIL the current drops below a certain level. Unfortunately, I doubt the LEAF's current monitors can resolve current below about 1A (or perhaps 0.5A). Does anyone know the resolution of this measurement in the LEAF when measuring low currents? If the resolution is really 1A, then it may simply decide "Since the current is now below 1A I cannot measure any further change, so I'm dropping into float."

 

[QueenBee]

So random question. Doesn't anyone else measure about 50 volts AC between either terminal of their battery tender and their buildings ground/neutral?

Yes. I measure ~64VAC from neutral or ground to either battery terminal of my BatteryMinder 1500. But both of my maintenance battery chargers are fully isolated between the AC input and the DC output. I expect the AC is due to the small capacitance of the transformer inducing the AC waveform on the outputs due to the extremely high impedance it sees. I don't think there is anything to worry about.

I noticed because my I felt tingling between my knee and license plate while using my battery minder 12248. Tested a friends batterytender brand and saw the same thing. Probably rare that anyone else would ever experience this as I was barefoot, wearing shorts, and have an all metal bracket for the plate that mounts to the tow hook. You also have to just barely touch it so the current is concentrated to just a little bit of sensitive skin. Thanks for confirming that mine isn't defective.

 

[RegGuheert]

I noticed because my I felt tingling between my knee and license plate while using my battery minder 12248.

Oh! I was wondering why you measured that.

Tested a friends batterytender brand and saw the same thing. Probably rare that anyone else would ever experience this as I was barefoot, wearing shorts, and have an all metal bracket for the plate that mounts to the tow hook. You also have to just barely touch it so the current is concentrated to just a little bit of sensitive skin. Thanks for confirming that mine isn't defective.

Well, the signal is definitely there. While the DC impedance is certainly very high on my unit, it sounds like the AC impedance may be quite a bit lower.

I'm glad you weren't injured!

 

[69800]

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V

Wednesday's voltage was 12.44V: It's back down to what it was on Monday when I had the ELM-327 plugged in.

buy the way may wife is going on vacation so the leaf will be parked for 4 days. Do you want me to record anything specific? I was thinking about 5 min interval for 4 days while plugged in.

That might be interesting, although I do not tend to keep the LEAF plugged in. I disabled the timers about a year ago and we simply plug it in when we want to charge.

What would you like to see?

I'd be most interested in seeing a 24-hour (or less) plot with the samples at 10-second intervals including at least one charge and one driving cycle. Thanks!

you got it. I will do it this week

 

[RegGuheert]

you got it. I will do it this week

Thanks!

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V>3C15D>12.57V>12.43V>12.40V>3C7D>12.49V

The car sat untouched for about 18 hours before this reading, so it is a decent value. SOC is up a bit from Sunday morning.

 

[RegGuheert]

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V>3C15D>12.57V>12.43V>12.40V>3C7D>12.49V>12.43V

12.43V today. Should be down to where it was on Sunday tomorrow.

 

[69800]

Here is a one day charge profile. True absorbsion charging takes place at 14.3 volts and float voltage of 13.1 volt only hold the charge where it currently is at. In one day using a 10 second recording interval the 12v battery got a grand total of 120 seconds of charging at 14.3v

 

[Nubo]

Here is a one day charge profile. True absorbsion charging takes place at 14.3 volts and float voltage of 13.1 volt only hold the charge where it currently is at. In one day using a 10 second recording interval the 12v battery got a grand total of 120 seconds of charging at 14.3v

We can't draw any conclusions on whether that absorption charge was adequate, since the amperage is unknown.

 

[RegGuheert]

Here is a one day charge profile. True absorbsion charging takes place at 14.3 volts and float voltage of 13.1 volt only hold the charge where it currently is at. In one day using a 10 second recording interval the 12v battery got a grand total of 120 seconds of charging at 14.3v

We can't draw any conclusions on whether that absorption charge was adequate, since the amperage is unknown.

Yes, we can. It doesn't matter what the current is. Lead-acid batteries CANNOT absorb the charge instantly due to the thickness of the material on the plates. If you do not dwell at the absorption voltage for many hours, there will be lead sulfate which does not get recharged back into lead and sulfuric acid. What you get with a brief absorption phase as is done in the LEAF is known as a surface charge.

 

[RegGuheert]

12.87V>12.78V>12.71V>12.64V>2C4D>1C2D>12.57V>1C5D>12.44V>12.47V>12.44V>3C15D>12.57V>12.43V>12.40V>3C7D>12.49V>12.43V>12.42V

12.42V today. That's a very small voltage drop for a single day of sitting. Lower than I have ever recorded before...

 

[QueenBee]

Here is a one day charge profile. True absorbsion charging takes place at 14.3 volts and float voltage of 13.1 volt only hold the charge where it currently is at. In one day using a 10 second recording interval the 12v battery got a grand total of 120 seconds of charging at 14.3v

We can't draw any conclusions on whether that absorption charge was adequate, since the amperage is unknown.

Does putting in roughly 10 watts of power at 13.1 volts into the battery really not charge it?

 

[RegGuheert]

Does putting in roughly 10 watts of power at 13.1 volts into the battery really not charge it?

It really doesn't, not to full. (And if it IS putting in ~10W, then the battery is nowhere near full. If the LEAF OEM battery is close to full, the power flow at 13.1V will be significantly less than 1W.) In the case of OP's battery, 13.1V is LOWER than the resting voltage of the fully-charged battery, which was measured to be 13.3V.

But even in the case of the LEAF OEM battery which has a resting voltage of 12.9V or lower when fully charged, the battery will NOT charge to full at 13.1V. (It will charge up to about 70% or perhaps a bit more if it is below that level.)

 

[QueenBee]

Does putting in roughly 10 watts of power at 13.1 volts into the battery really not charge it?

It really doesn't, not to full. (And if it IS putting in ~10W, then the battery is nowhere near full. If the LEAF OEM battery is close to full, the power flow at 13.1V will be significantly less than 1W.) In the case of OP's battery, 13.1V is LOWER than the resting voltage of the fully-charged battery, which was measured to be 13.3V.

But even in the case of the LEAF OEM battery which has a resting voltage of 12.9V or lower when fully charged, the battery will NOT charge to full at 13.1V. (It will charge up to about 70% or perhaps a bit more if it is below that level.)

I guess it was a big assumption to assume that Nissan's measurement was accurate but my LEAFSpy always reports about 13 volts and flips between just above 1 amp and just below 1 amp.