Solutions to 12 Volt Batteries and Chargers Posted Here

[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.)

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.

Like I said, if your battery is at a lower state-of-charge (and it normally is in the LEAF), it will accept some charge at 13.1V. But the battery will never get fully charged at that voltage.

Here is the plot 69800 provided earlier today, but plotted in Excel with gridlines etc.:

Note that after both the charging and the driving events, the battery voltage, and hence its state-of-charge, is lower or the same as it was before the event. No net charge was added. It was either lost or is the same. That is what happens when you have a full, or mostly full, 12V battery in the LEAF. Once it discharges it to around 60-70%, it can add a little each time and therefore maintain it there. Unfortunately, the lead sulfate is hardening all the while.

 

[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>12.40V

12.40V today. Another small voltage drop today...

 

[TimLee]

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."

I don't know the accuracy of the current monitor on the 12V battery negative cable.
But at the high end it can display 120 amps.
For a single monitor it would be unusual for the bottom end to be better than 0.5 %.
That would be 0.6 amps.
But top end of range is probably bit more than 120.
So resolution may be around 0.7 amps.

To do better than that they could use multiple current measurements.
But unlikely they did that.

So the charging approach is flawed by both measurement accuracy, current flows that occur when vehicle is Off, and loss of capacity that does not show up as current.

Why Nissan and Toyota thought keeping a 12V lead acid battery only charged to 70% was a good idea is baffling.
But that appears to be what they did.

 

[jpadc]

Why Nissan and Toyota thought keeping a 12V lead acid battery only charged to 70% was a good idea is baffling. But that appears to be what they did.

Would it seem too cynical if I said they figured that under most user driving conditions that would likely be sufficient to get it beyond 3yr/36,000mi warranty? But more to the point, I wonder if they believed more extended time at 14+ volts (which would be the voltage throughout the car) would be harder on other more sensitive electronic components in the vehicle and they were more concerned about protecting those components rather than the relatively cheap 12 volt battery. Way outside my expertise, but I assume that higher voltages sent to devices intended for ~12 volts would tend to produce more heat leading possibly to premature failure???

On a side note: Thanks RegGuheert and others here for all the data about this. Having had 12 battery issues in both my Prius and LEAF, I appreciate users who are identifying potential issues and working on finding ways to mitigate them.

 

[RegGuheert]

Would it seem too cynical if I said they figured that under most user driving conditions that would likely be sufficient to get it beyond 3yr/36,000mi warranty?

No, I think you are dead-on here. But I also think wasting $100+ batteries is bad for the environment, even if they are recycled.

But more to the point, I wonder if they believed more extended time at 14+ volts (which would be the voltage throughout the car) would be harder on other more sensitive electronic components in the vehicle and they were more concerned about protecting those components rather than the relatively cheap 12 volt battery.

I have a bit more trouble with this idea. Yes, the amount of sulfuric acid in the engine compartment would likely be higher, but ALL of my other vehicles live at 14.5V when on and I don't see anything corroding in there. OTOH, they DO use up all the water in at least one cell in about seven years.

The bigger issue the LEAF designers faced is that the car is ON about four times as long as a normal car when you include charging time. So if they had used a normal 14.5V-always charging system, they would have killed the batteries in less than about two years just from water loss. So that's no solution for the LEAF, either. (But it doesn't explain the Prius.)

That's why I say I like all the pieces they have provided and only think a software tweak is in order. Every week or every X charges, just leave the voltage at 14.5V during the entire time the traction battery is being charged. And they may even be doing this, as I sometimes see it at 14.5V near the end of a charging session. So perhaps only the frequency needs to change. I'm hopeful they will make adjustments over time to their algorithms, but I don't hold out much hope that they will reprogram our older cars.

Way outside my expertise, but I assume that higher voltages sent to devices intended for ~12 volts would tend to produce more heat leading possibly to premature failure???

That depends on the device. It is certainly true for lights. Many electronic loads including many LEDs have their own power converters, so they draw approximately the same amount of power regardless of the voltage supplied. But as a previous poster pointed out earlier in this thread, operating halogen headlights designed for 14.5V at 13.1V greatly reduces their brightness, so there is certainly a trade-off there.

On a side note: Thanks RegGuheert and others here for all the data about this. Having had 12 battery issues in both my Prius and LEAF, I appreciate users who are identifying potential issues and working on finding ways to mitigate them.

You're welcome!

Personally, I'm not thrilled about charging the 12V battery every month or so. OTOH, I really appreciate learning about the BatteryMinder that another poster pointed out in a different thread. That thing is nothing short of amazing!

 

[lorenfb]

But I also think wasting $100+ batteries

Where is the evidence of this? This thread (over 150 posts) has not provided any data/proof of a reduced
12V battery longevity in the Leaf. Where are the reports from Leaf owners, media reports, or class action
suits of a high/abnormal replacement rate?

The only real data and/or conclusion that all Leaf owners can agree on is that the Leaf charges the 12V
battery to 13 volts! Where's the link between that and an actual reduced longevity other that speculation?

 

[lorenfb]

Why Nissan and Toyota thought keeping a 12V lead acid battery only charged to 70% was a good idea is baffling.
But that appears to be what they did.

So now we have two OEMs (major volume WW manufacturers) that fail to understand the proper 12V battery
charging, right?

 

[lorenfb]

Battery maintainer (external charger w/o special micro-controller type charger) battery voltage data for
various vehicles with access to for data measurements; vehicle, battery age, battery maintained voltage,
frequency of driving:

BMW 4 Dr, 4 yrs, 13.04, once/6 months
M/B Coupe, 6 yrs, 13.04, once/3 months
Mini Cooper S, 7 yrs, 12.61 once/6 months
Nissan Pathfinder, 3 yrs, 12.44, once/week (only solar panel with max. of 50-75 ma)
Suzuki GSX 1000, 11 yrs, 12.88, once/6 months

All the above are lead-acid batteries.

Above are my longevity data. My 12V lead acid batteries don't have shortened longevity or do they?

 

[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>12.40V>3C10D>12.48V

12.48V today. A slight gain during the last two days with 13 charging opportunities.

 

[69800]

RegGuheert is right.

I have checked the output voltage of all seven of my cars and my boats. Every one of them runs at about 14 Volts while they are running. I stopped into my electrical shop the other day. They rebuild generators and alternators all day long. I asked them if they had ever seen an alternator working correctly that put out only 13.1 Volts. They told me, as I already knew, that back in the 60s and may be early 70s when the cars were using mechanical voltage regulators they would find alternators charging in the mid-13 V range. Since the auto manufacturers have gone to electronic regulators all of them charge at around 14 V. If you go on to the websites of high quality battery manufacturers and/or high quality battery charger manufacturers, many of them provide the algorithm of the type of charge they want the batteries to have or the type of charge their chargers put out. Every single one of them is using the same method. They all slowly charge the battery up into the 14 V range. They all hold the batteries at 14 V for a period of time (sometimes hours) in order for the battery to fully absorb the charge. Then they all drop the voltage down to around 13.1 or 13.2 in order to hold the charge at full but so as to not gas the battery. Facts are facts. The leaf simply does not fully charge the battery. And of conversation.

 

[GlennD]

RegGuheert is right.

I have checked the output voltage of all seven of my cars and my boats. Every one of them runs at about 14 Volts while they are running. I stopped into my electrical shop the other day. They rebuild generators and alternators all day long. I asked them if they had ever seen an alternator working correctly that put out only 13.1 Volts. They told me, as I already knew, that back in the 60s and may be early 70s when the cars were using mechanical voltage regulators they would find alternators charging in the mid-13 V range. Since the auto manufacturers have gone to electronic regulators all of them charge at around 14 V. If you go on to the websites of high quality battery manufacturers and/or high quality battery charger manufacturers, many of them provide the algorithm of the type of charge they want the batteries to have or the type of charge their chargers put out. Every single one of them is using the same method. They all slowly charge the battery up into the 14 V range. They all hold the batteries at 14 V for a period of time (sometimes hours) in order for the battery to fully absorb the charge. Then they all drop the voltage down to around 13.1 or 13.2 in order to hold the charge at full but so as to not gas the battery. Facts are facts. The leaf simply does not fully charge the battery. And of conversation.

I transferred the cigarette lighter voltmeter from my Leaf to my B Class. Tesla does initially charge at 14.9V but it quickly backs down to 14.1V. I feel it properly charges my car.


Remember digital meters are at best plus or minus one digit. 14.9V could be 14.8V or 15V.

 

[QueenBee]

RegGuheert is right.

I have checked the output voltage of all seven of my cars and my boats. Every one of them runs at about 14 Volts while they are running. I stopped into my electrical shop the other day. They rebuild generators and alternators all day long. I asked them if they had ever seen an alternator working correctly that put out only 13.1 Volts. They told me, as I already knew, that back in the 60s and may be early 70s when the cars were using mechanical voltage regulators they would find alternators charging in the mid-13 V range. Since the auto manufacturers have gone to electronic regulators all of them charge at around 14 V. If you go on to the websites of high quality battery manufacturers and/or high quality battery charger manufacturers, many of them provide the algorithm of the type of charge they want the batteries to have or the type of charge their chargers put out. Every single one of them is using the same method. They all slowly charge the battery up into the 14 V range. They all hold the batteries at 14 V for a period of time (sometimes hours) in order for the battery to fully absorb the charge. Then they all drop the voltage down to around 13.1 or 13.2 in order to hold the charge at full but so as to not gas the battery. Facts are facts. The leaf simply does not fully charge the battery. And of conversation.

I transferred the cigarette lighter voltmeter from my Leaf to my B Class. Tesla does initially charge at 14.9V but it quickly backs down to 14.1V. I feel it properly charges my car.


Remember digital meters are at best plus or minus one digit. 14.9V could be 14.8V or 15V.

So the Tesla algorithm is alway at 14.1 or above when the DC to DC converter is on?

 

[GlennD]

14.1 indicated. it could be 14.0 or 14.2V.

 

[QueenBee]

14.1 indicated. it could be 14.0 or 14.2V.

That's really interesting information. So I'm really curious if it just this for a certain length of time or if it is literally always at that voltage or above including during charging of the traction battery.

 

[RegGuheert]

I transferred the cigarette lighter voltmeter from my Leaf to my B Class. Tesla does initially charge at 14.9V but it quickly backs down to 14.1V. I feel it properly charges my car.

Does the B-class come with a sealed AGM or a normal flooded battery? Those voltages sound like what you might use for an AGM like 69800 just bought.

That said, I'd be fine with those voltages for the LEAF, even with a flooded battery, as long as it did not remain at 14.9V too long. At least the 14.1V should fully charge the battery, given enough time.

 

[QueenBee]

I transferred the cigarette lighter voltmeter from my Leaf to my B Class. Tesla does initially charge at 14.9V but it quickly backs down to 14.1V. I feel it properly charges my car.

Does the B-class come with a sealed AGM or a normal flooded battery? Those voltages sound like what you might use for an AGM like 69800 just bought.

That said, I'd be fine with those voltages for the LEAF, even with a flooded battery, as long as it did not remain at 14.9V too long. At least the 14.1V should fully charge the battery, given enough time.

Looks like that's the case as presumably they would have used the same battery as the Model S. Obviously the reason for the failures is likely different but from the sounds of it we are doing a lot better with regards to 12 volt battery life than Model S owners. "They are seeing most last about a year to 1 and 1/2 years" Though the one thing I really like is that the car actually reports when the 12 volt battery needs to be replaced and at least some times prior to the owner evening knowing.

After the early batch of batteries in early 2013, Tesla went with a 33 Ah absorbed glass mat lead-acid (sealed gel cell) DCS-33RIT and updated all early cars to this battery.

http://www.cdtechno.com/pdf/lit/dcs_33.pdf" onclick="window.open(this.href);return false;

They may have more than one source, so I doubt this is the only battery in the wild.

http://my.teslamotors.com/forum/forums/ok-here-latest-12v-battery" onclick="window.open(this.href);return false;

 

[lorenfb]

I transferred the cigarette lighter voltmeter from my Leaf to my B Class. Tesla does initially charge at 14.9V but it quickly backs down to 14.1V. I feel it properly charges my car.

So, that's just anecdotal!

Do Tesla 12V lead-acid batteries have a lower replacement rate and thus a better longevity than the Leaf's
12V lead-acid battery, given the value of the Leaf's charging voltage?

That's the issue!

 

[RegGuheert]

After the early batch of batteries in early 2013, Tesla went with a 33 Ah absorbed glass mat lead-acid (sealed gel cell) DCS-33RIT and updated all early cars to this battery.

http://www.cdtechno.com/pdf/lit/dcs_33.pdf" onclick="window.open(this.href);return false;

They may have more than one source, so I doubt this is the only battery in the wild.

http://my.teslamotors.com/forum/forums/ok-here-latest-12v-battery" onclick="window.open(this.href);return false;

Thanks for the link. So the Tesla Model S trashes a $150 12V lead-acid battery about every 12 months (and it takes about 90 minutes to replace it). There is nothing environmentally friendly about that!

I suspect Tesla will have an uphill battle to get this issue resolved, since they probably simply have too much of a nighttime load on that little battery.

But we don't know what is causing the Model S 12V failures. It could be sulfation issues like in the LEAF or overcharging issues or even both. I don't see data on the Tesla 12V battery like we have here to be able to tell.

With the LEAF it is clear: The batteries are rarely, if ever overcharged, so they do not suffer from water usage. At the same time, they are rarely, if ever, fully charged, which leads to early death due to sulfation. Because there is almost no water usage today, they can trade that against the sulfation issue to achieve better overall 12V battery life (just as some of us owners are doing manually). Whether they choose to do that or not is up to them.

 

[essaunders]

I've read a bunch of the posts but not found an answer to my question: What is a recommended 12V battery replacement?


What I've found:

My local dealer wants $95 for the battery ($164 installed) but that only has a "12/12" warranty.

The local Interstate shop will sell me a "NP51R" for $118 (installed or not).

It looks like I can order an Optima YellowTop (YELD51R) from my local PepBosy for $190 for installation tomorrow.

Walmart has a MAXX_51R for $107 with 3 year warranty

AAA will come out and (supposedly) sell me a new installed battery for no more than ~$163. (LEAF isn't listed on their quote system, but a Nissan GT-R which also uses a 51R quotes out at $116)



Is it worth getting an AGM? I did spring for an yellowtop in my '07 prius.

 

[RegGuheert]

I've read a bunch of the posts but not found an answer to my question: What is a recommended 12V battery replacement?

I did provide this post which details the different suggestions which have been provided by various posters.

What I've found:

My local dealer wants $95 for the battery ($164 installed) but that only has a "12/12" warranty.

The local Interstate shop will sell me a "NP51R" for $118 (installed or not).

It looks like I can order an Optima YellowTop (YELD51R) from my local PepBosy for $190 for installation tomorrow.

Walmart has a MAXX_51R for $107 with 3 year warranty

AAA will come out and (supposedly) sell me a new installed battery for no more than ~$163. (LEAF isn't listed on their quote system, but a Nissan GT-R which also uses a 51R quotes out at $116)



Is it worth getting an AGM? I did spring for an yellowtop in my '07 prius.

Personally, I recommend purchasing a normal, flooded 51R from Costco. I purchased one of those for my Mom's Honda Civic Hybrid about 6 months ago and paid about $73 for it with a 36-month warranty (IIRC). This link indicates that Costco's fitment code 11 is the 51R.

But I don't recommend replacing it unless it is dead or mostly dead. Is yours having issues?