Solutions to 12 Volt Batteries and Chargers Posted Here

[RegGuheert]

Unfortunately, once lead sulfate has hardened from a soft paste to hard crystals, the capacity that it represents is lost. Normal charging will not ever recover that capacity.

Yes, I agree. But the key issue is what the minimum driving/charging-voltage/frequency is to avoid this problematic sulfate mode. It appears that your hypothesis is that there isn't any, for which as yet no data have been presented.

Lead sulfate can harden in as little as 24 hours in hot conditions. I have demonstrated that the LEAF does not return the battery to a full charge for as long as 21 days. Sulfation is not an all-or-nothing issue. It is a gradual degradation process by which a battery dies a slow death. The kind of charging done by the LEAF's charger greatly increases the rate of sulfation.

Furthermore, the data I presented up-stream, hardly robust, over the years indicates that battery maintenance charging between 13.0 and 13.5 will keep a 12V lead-acid in a reliable SOC, i.e. with near output Ahr and cold cranking amps as original for over five years.

That's hardly relevant here. The LEAF does not fully charge the 12V battery and then maintain that battery at a float (maintenance) voltage continuously. Rather, it discharges the battery over time and never fully recharges it. (Except in rather cold weather, it can't after three weeks without a full charge, even if it tries to.)

If data are available indicating the rate of the formation of sulfate over time and charging voltage, please provide it. Ideally one might expect a family of curves where the X-axis is time and the Y-axis is percent sulfate formation with each curve representing the maintenance charging voltage.

The lead sulfate forms during the discharge reaction. That is why holding a FULLY-CHARGED battery at a float (maintenance) voltage prevents sulfation. The real question is how long does it take for lead sulfate to harden. The answer is that it depends on the temperature:

Causes of battery sulfation:

- Batteries sit too long between charges. As little as 24 hours in hot weather and several days in cooler weather.
- Battery is stored without some type of energy input.
- Undercharging of a battery to only 90% of capacity will allow sulfation of the battery using the 10% of battery chemistry not reactivated by not completing the charging cycle.
- Low electrolyte level - battery plates exposed to air will immediately sulfate.
- Incorrect charging levels and settings. Rolls recommends a 3-phase charge cycle (Bulk, Absorption & Float). See State of Charge & charging information.
- The longer a battery sits and is not re-charged the more damaging sulfation build up there may be on the plates.

Studies have noted that nearly half of the L-16 battery capacity can be lost if the regulation voltage is too low and the time between finish-charges is too long.

In normal use, battery plates are getting sulfated all the time. When a battery is being discharged the lead active material on the plates will react with the sulfate from the electrolyte forming a lead sulfate on the plates. When there is no lead active material and or sulfate from the electrolyte remaining the battery then is completely discharged. After a battery reaches this state, it must be recharged. During recharge, the lead sulfate is reconverted into lead active material and the sulfate returned to the electrolyte.

When the sulfate is removed from the electrolyte the specific gravity is reduced and the reverse takes place when the sulfate is returned to the electrolyte. This is why the state of charge can be determined with the use of a hydrometer.

If a battery is left standing in a discharged condition the lead sulfate will become hard and have a high electrical resistance. This is what is normally called a sulfated battery. The lead sulfate may become so hard that normal recharging will not break it down. Most charging sources, engine alternators and battery chargers, are voltage regulated. Their charging current is controlled by the battery's state of charge. During charging, battery voltage rises until it meets the charger's regulated voltage, lowering the current output along the way.

When hard sulfate is present, the battery shows a false voltage, higher than it's true voltage, fooling the voltage regulator into thinking that the battery is fully charged. This causes the charger to prematurely lower it's current output, leaving the battery discharged. Charging at a higher than normal voltage and low current may be necessary to break down the hardened sulfate.

Hardened sulfate also forms in a battery that is constantly being cycled in the middle of its capacity range (somewhere between 80% charged and 80% discharged), and is never recharged to 100%. Over time, a portion of the plate's active materials turns into hard sulfate. If the battery is continually cycled in this manner, it will lose more and more of its capacity until it no longer has enough capacity to perform the task for which it was intended. An equalizing charge, applied routinely every three to four weeks, should prevent the sulfate from hardening.

In both cases, the fact that the battery "won't take a charge" is a result of improper charging procedures which allowed the sulfate to harden. In most instances, it is possible to salvage a battery with hardened sulfate. The battery should be charged from an outside source at 2.6 to 2.7 - volts per cell and a low current rate (approximately 5 Amps for small batteries and 10-Amps for larger ones) until the specific gravity of the electrolyte starts to rise. (This indicates that the sulfate is breaking down.) Be careful not to let the internal temperature of the battery rise above 125° F. If it does, turn the charger off and let the battery cool. Then, continue charging until each cell in the battery is brought up to full charge (nominal 1.265 specific gravity or higher).This time needed to complete this recharge depends on how long the battery has been discharged and how hard the sulfate has become.

Lead-acid battery sulfation is a well-known phenomenon and proper charging techniques to minimize the hardening of lead sulfate are well-understood. The LEAF battery charger violates many of these well-known principles and the result is premature failure of the 12V battery due to sulfation.

 

[lorenfb]

As was said before, still waiting for a robust and more scientific approach before drawing a conclusion.
Let's not get into the typical back-and-forth semantic posts found in other threads to obfuscate
a valid conclusion. So why do a disservice to the Leaf owners by recommending a change in one's
behavior based on anecdotal data.

 

[DaveEV]

I'm not sure what other data you need.

There's already plenty of data showing that the LEAF does not adequately charge the 12v battery.

Do you need a data logger logging at 1 second intervals at a year to convince you? If so, please feel free to gather that data yourself.

I can tell you that right now my 12V is resting at 12.5V and that was after pumping 10Ah into it last night with a basic 12V charger. Resting voltage was worse yesterday, before I charged it, below 12V.

I started charging it to see what the car would do and it put 14.5V into the battery for less than a minute before ramping down to 13.0V. Usually if I watch the 12V when driving off in the morning it stays up for at least a few minutes.

It's clear that topping off the 12V battery with a good lead-acid charger every now and then will prolong the life of it.

 

[RegGuheert]

I can tell you that right now my 12V is resting at 12.5V and that was after pumping 10Ah into it last night with a basic 12V charger.

At least your battery is still accepting *some* charge. But 10Ah starting from below 12V is way down from new, which I would expect to be over 20Ah for such a charge.

Resting voltage was worse yesterday, before I charged it, below 12V.

I don't think I've ever seen a voltage below 12V in our LEAF. Once I found out (a couple of years ago) that my battery was spending much of its life around 12.2V, that's when I decided to start charging it occasionally. Unfortunately, the basic three-stage charger/maintainer I had (and still have) could not get the battery to accept a full charge. This was evidenced by the resting voltage quickly dropping back to ~12.3V after a full charge cycle.

That's when I decided to purchase the BatteryMinder 1500 on the recommendation of another forum member. If a battery is sulfated, the difference between my two chargers is like night and day, even though they both charge at 1.5A during the bulk phase and use roughly the same absorption voltage. With the old charger, the voltage will steadily rise to ~14.5V and then it will it will drop back to float after just a few minutes. If I let the same battery sit overnight and then put it on the BatteryMinder, the voltage will rise up, sometimes to around 14.0V and then it will stabilize and then start to fall as the sulfate begins to be removed. I've seen the voltage drop by as much as 0.5V during the bulk phase of charging. It will often charge a battery for 10 or even 20 hours after the other charger dropped to float within about 30 minutes.

As you have seen in my posts, the battery in my LEAF can now achieve a resting voltage of 12.87V after being charged using the new charger. It has been charged intermittently over the past year, including a multi-week desulfation (which is mostly done at a float voltage) during vacation last spring.

 

[TimLee]

...I'm interested to learn under what conditions the charging system in the LEAF triggers the long-term 14.5V charge that occurs infrequently. Does anyone have data about that?

It has to be based on the net current loss the LEAF has measured.
I don't think it is based on voltage like a battery maintainer true charger.
For example, when I killed the 12V by forgetting it was sitting in garage and traction battery shut off and the 12V drained down to extremely low.

But to start the LEAF had to jump with ICE.
So if LEAF did check 12V voltage before it started it would have seen a normal voltage.
But even so it knew the 12V was extremely low because it had observed a huge net discharge so it held 14.5V initially at 120 amps for a very long time.

But it does not know about the drain when the LEAF is off, in my case a large % of that being the ELM Bluetooth adapter.

The LEAF approach with only two voltages might be good if it was able to monitor battery net current all the time.
But it does not.

 

[lorenfb]

I'm not sure what other data you need.

Where are the documented reports, i.e. exclusive of this forum, that indicates an abnormal failure rate
for the 12V battery in the Leaf? Have the media reported on this? How about some comparative the data
that relates ICE versus Leaf 12V failure rates on average? If there's an inadequate Leaf 12V charging,
why hasn't Nissan done a simple firmware re-flash of the Leaf VCM/PDM ECUs?

Again:

If data are available indicating the rate of the formation of sulfate over time and charging voltage,
please provide it. Ideally one might expect a family of curves where the X-axis is time and the Y-axis
is percent sulfate formation with each curve representing the maintenance charging voltage.

 

[RegGuheert]

After a full charge with an external charger there have been eight days, four traction-battery charges and eleven drive cycles. The battery voltage indicates a continued drop in SOC:

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

 

[lorenfb]

After a full charge with an external charger there have been eight days, four traction-battery charges and eleven drive cycles. The battery voltage indicates a continued drop in SOC:

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

A conclusion about a population is unscientific/irrational based on data from one sample in a population!

Start here with a sample size of 25 lead-acid batteries for a general population:

If data are available indicating the rate of the formation of sulfate over time and charging voltage,
please provide it. Ideally one might expect a family of curves where the X-axis is time and the Y-axis
is percent sulfate formation with each curve representing the maintenance charging voltage.

This then would be followed by a sample of 25 Leaf lead-acid batteries to establish a possible
correlation/fit to the previous sample of the general lead-acid battery population.

 

[DaveEV]

I don't think I've ever seen a voltage below 12V in our LEAF.

You know, I may be going off LeafDD voltage readings so the battery may have been under some extra load due to opening a door recently or something. I did just check the voltage again an it's down to 12.45V from 12.50V yesterday as one would expect based on your data-logging.

If there's an inadequate Leaf 12V charging,
why hasn't Nissan done a simple firmware re-flash of the Leaf VCM/PDM ECUs?

Because it's adequate to achieve a "normal" battery life in the LEAF, 3+ years as long as you don't further abuse it given the easy life the battery generally has other than the continuous under-charging.

But if you want the battery to last a long time - you need to keep it charged higher.

It's the same excuse Nissan would give if you complained about lack of regen as the battery degrades - "well gee, no-one's seen the brakes wearing out, so who cares?"

Start here with a sample size of 25 lead-acid batteries

:lol: Never going to happen. Because most people simply don't care as they are turning in their LEAF after their 2-3 year lease is up and the battery will make it 2-3 years without issue in most cases.

 

[lorenfb]

If there's an inadequate Leaf 12V charging,
why hasn't Nissan done a simple firmware re-flash of the Leaf VCM/PDM ECUs?

Because it's adequate to achieve a "normal" battery life in the LEAF, 3+ years as long as you don't further abuse it given the easy life the battery generally has other than the continuous under-charging.

Logical, but why would Nissan engineering not set a little higher voltage, e.g. 14.0 volts initially, if that would
reduce any potential Leaf battery problems? With all the OEM recalls, why would an OEM (Nissan) design-in
an inadequate charging algorithm. Surely they're aware of a potential sulfate problem if one were to occur
based on too low of a charging voltage. Nissan really has nothing to gain but a lot to lose from a bad
media report indicating Leaf owners having to replace the lead-acid batteries at an abnormal rate.

 

[Nubo]

If data are available indicating the rate of the formation of sulfate over time and charging voltage, please provide it. Ideally one might expect a family of curves where the X-axis is time and the Y-axis
is percent sulfate formation with each curve representing the maintenance charging voltage.

I haven't found anything like that, but I've come across a number of sources that seem to agree that sulfation begins to be a problem at below 80% state of charge.

 

[BrockWI]

My guess is Nissan initially counted on people charging at L1 or L2 3.3 rates most of the time, which would in turn lengthen out the charge time on the 12v battery as well. I believe they don't have a long absorb time at the higher voltage during normal driving conditions to consume power from the traction pack charging the 12v battery and let the grid do that when charging the traction pack.

In a way they did help the situation, inadvertently or not by eliminating the 80% charge rate. This gives the 12v aux battery a longer time to absorb while the main battery is being charge, which is what I think was intended from the get go.

As I noted before I have much less of an issue with the 12v battery when we were charging to 100% over the winter because we needed the range. Now that we are back to 80% charging, last weekend it took about 10 hours at 1.25 amps to bring the battery back to float on the battery tender.

 

[RegGuheert]

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

It went UP today! The reason is that I forgot to unplug the ELM327 last time I drove it, so there was a bit higher load on it for the 12.44V reading yesterday.

 

[lorenfb]

My guess is Nissan initially counted on people charging at L1 or L2 3.3 rates most of the time, which would in turn lengthen out the charge time on the 12v battery as well. I believe they don't have a long absorb time at the higher voltage during normal driving conditions to consume power from the traction pack charging the 12v battery and let the grid do that when charging the traction pack.

In a way they did help the situation, inadvertently or not by eliminating the 80% charge rate. This gives the 12v aux battery a longer time to absorb while the main battery is being charge, which is what I think was intended from the get go.

As I noted before I have much less of an issue with the 12v battery when we were charging to 100% over the winter because we needed the range. Now that we are back to 80% charging, last weekend it took about 10 hours at 1.25 amps to bring the battery back to float on the battery tender.

Thanks. Good insight.

 

[69800]

RegGuheert

do you realize how much time you just spent convincing one person that the charging rate on the leaf is not adequate? Let them do their own searching through all of the data on this site and figure it out for themselves. It is way to time consuming to convince one person that the earth is not flat. They can buy all of the batteries they want.

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. What would you like to see?

 

[lorenfb]

Still waiting for valid longitudinal data to resolve these issues:

1. Whether the Leaf provides an inadequate charging voltage (13.1) resulting in reduced battery longevity,
and if so what is an appropriate charging voltage for long term non-use of a lead-acid battery.
2. Whether the Leaf requires supplemental lead-acid battery charging and at what frequency.

Furthermore, most key to any conclusion being arrived at is whether any data presented in this
thread is representative of the Leaf population as a whole, i.e. by a few Leaf owners.

After a full charge with an external charger there have been eight days, four traction-battery charges and eleven drive cycles. The battery voltage indicates a continued drop in SOC:

Why is voltage used as a measure of SOC for a lead-acid battery? In the automotive industry, a load test
is performed as a measure of SOC/condition. A marginal battery, for example, may indicate 14.25 volts
shortly after removal of a battery charger, but when load tested the voltage my drop to less than 10 volts.
A load test is always performed once charging is completed while measuring the voltage.

Yes, SOC of capacity is a relative measure of a battery's present state to its maximum possible state
(not its original new state) at a point in time, but doesn't really provide data on the battery's actual
state/condition relative to a new battery or its functionality under loaded conditions. Using voltage SOC
versus Ahr SOC as a measure of battery's charge level has marginal utility in evaluating a battery's
relative condition. A lead-acid battery without a maintaining charger will always exhibit a negative slope
relative to its output voltage over time.

With a lithium battery, e.g. the Leaf's, one doesn't monitor the battery's voltage when measuring SOC,
but one uses the Ahr values to calculate SOC. Using actual Leaf data;

SOC - 62%, Voltage - 386, Ahr - 36
SOC - 45%, Voltage - 375, Ahr - 27

As can be noted, the Lithium battery's output voltage changes little as its Ahr SOC declines. Although,
a lead-acid battery's voltage decreases more than a Lithium battery as it's capacity decreases or with
time, using its voltage as a measure of SOC is misleading and of minimal value, especially when one's
data points are just voltage changes in hundreds of millivolts of a 12 volt battery.

 

[RegGuheert]

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!

 

[dhanson865]

As can be noted, the Lithium battery's output voltage changes little as its Ahr SOC declines. Although,
a lead-acid battery's voltage decreases more than a Lithium battery as it's capacity decreases or with
time, using its voltage as a measure of SOC is misleading and of minimal value, especially when one's
data points are just voltage changes in hundreds of millivolts of a 12 volt battery.

I'm still trying to decide if you are trolling this thread on purpose or just don't understand battery technology.

 

[lorenfb]

I'm still trying to decide if you are trolling this thread on purpose or just don't understand battery technology.

And what is your profound battery knowledge? Maybe another one that allowed his Leaf battery to fully
discharge a few times and now claims that the Leaf has inadequate charging because his battery is
now marginal, right? Are you also measuring a lead-acid battery's SOC by tracking miilivolts too? That'll
yield some significant inference about the Leaf's battery population, right?

And here's one of your thread posts, but like most just anecdotal:

If you aren't testing your 12v battery and aren't charging it outside the cars built in charging I guarantee you it is below OptimaVisit the Optima Foruml. You just don't know it yet. Unlike an ICE vehicle the with starter drag there is no in the face of the user kind of warning that your battery is low. Your car may not start one day or the electronics might go and do random things but you won't know what it is for sure until you test the 12v battery.

"I guarantee you", really? And where are your well researched data, please?

Imagine a battery is fully charged at 13.0 and useless for starting the car at 11.0 just for round numbers, now imagine that every time you drive to the car it charges +0.1 and drains -0.2. The net change per trip would be -0.1 and it would take 20 trips to hit the one where you couldn't start the car. Obviously not happening that quickly but it's very close to what happens for some drivers.

Profound!

Again, why aren't load tests being performed on the potentially inadequately charged Leaf 12V lead-acid
batteries as a measure of capacity loss?

 

[RegGuheert]

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

So, after a total of 18 12V charging opportunities over the past two days, the net charge lost in the previous four days has been replaced.