How's your 12v battery health?

[DaveinOlyWA]

after 29 months, my battery is perpetually low (12.25-12.4) but it has never failed to start. If you drive frequently, I think you have little to worry about. My LEAF has probably sit more than 24 hours half a dozen times including one stint of 6 days last Summer and another stint of 5 days last Spring. So hopefully the battery will squeak by for the remaining 7 months on my lease...

Not to read like a broken record (?) but... how do you charge? My theory is that the Leaf was originally developed to spend hours a day on a charger, and that the software that keeps the accessory battery charged still 'assumes' that this is the case. Driving the car should also charge it, but does anyone know what the proportions are? In any event, batteries that *could* last for five years easily are being abused by being kept chronically below 90% SOC, for no good reason that I can see. I'm sure mine will easily last two years the way I'm charging and driving, but I think I'll top that battery off every week or two - out of pity if nothing else.

At home, I charge to 100% (this morning was first time in recent memory that I did not fully charge overnight) 95% of the time with EVSE upgrade 1.0 (charges at 12 amps, 240 volts) I also use public charging 80% fast charge, 20% 240 charging. 240 charging is generally to 100% or near it and happens 3-4 times a month. Fast charging only to 65% or less generally and done 1-4 times a week.

Rarely does the car sit more than 14 hours at the most without being driven which is probably the main contributing reason I am not having battery issues. Everyone I am aware of that had issues, it always happened during periods when the car was parked but for relatively short periods of time. One guy in the Seattle area who drives a lot (he has over 40,000 miles on his LEAF) had his car idle over New Years Eve weekend, just short of 4 days and that was enough to kill his battery. One thing that probably contributed to his issues is that he travels a lot for work and has family in Alaska so its common for his LEAF to sit 1-3 days at the airport. probably allows it to cycle just deep enough and with the parking structure of multi-story reinforced concrete, Carwings would be working twice as hard looking for a signal there and so on...

So question, when you guys are measuring the voltage of the battery resting if you are leaving the battery connected to the car will that bit in fact be a resting voltage and this will be lower than if it was resting and disconnected? So maybe the low SOCs being measured are not accurate and the real SOC is much higher?

yes, the battery should read lower when connected because there is always a call for power. Now that call for power can vary widely depending on whether or not Carwings is active or not. It is conceivable that you could be checking it when Carwings is using power to transmit or receive a signal but to minimize that option, i don't have my car locked and i "try" to go out and check the voltage without bringing the Fob near the car which could cause the car to wake up.

now, i have also had random measurements when the battery was 13.2 volts (fairly common) and when it was 12.8ish which is where a normally healthy battery should be but on the cases when i got readings under 12.4, i would recheck it in hourly intervals at least twice and the voltage did not change significantly so pretty sure it was just a normal voltage reading.

I actually took measurements diligently for a while trying to put together some sort theory on when and why the 12 volt battery would charge from the traction battery but simply did not get enough consistent readings to see a pattern.

 

[LeftieBiker]

I see a *possible* pattern, and that is one in which car charging is the primary source of recovery charging for the accessory battery. Driving seems to use enough juice to make it almost a wash with what the DC/DC converter provides the battery then, which would be why people who drive a lot can still see the battery go dead after a relatively short period of time. 12 volt storage batteries (especially sealed ones!) can't accept charge nearly as fast as lithium ion packs, so when the packs are fast charged the accessory battery lags behind in charge, and while driving it's providing almost as much power as it's receiving. That's how it looks to me, anyway...

 

[Stoaty]

I left the CTEK charger on the 12 volt battery for about 8 hours. Green light hasn't come on yet. Stopped charging, voltage measured about 13.3 volts (but didn't wait 30 minutes yet to see where voltage settles). Is this to be expected? I didn't think it would take this long. Thoughts?

Follow-up on my use of the CTEK charger. After I posted, went out and saw the green light on. Unplugged the CTEK, waited 30 minutes and checked the voltage - 12.95. Put the Leaf back on the CTEK for about 18 hours, unplugged it, waited an hour, checked voltage - 12.85. Let the Leaf sit overnite, checked the voltage - 12.53. I don't know if this means the Leaf used a bit of charge overnight, or if 12.53 (about what I got before using the CTEK) is the best my battery can do.

PS How often should one check the fluid levels in the 12 volt battery? So far, I have checked it... zero times. I assume the caps just unscrew; couldn't take them off with bare hands, haven't used a wrench yet.

 

[DaveEV]

PS How often should one check the fluid levels in the 12 volt battery? So far, I have checked it... zero times. I assume the caps just unscrew; couldn't take them off with bare hands, haven't used a wrench yet.

You can check fluid levels by shining a flashlight at the front of the case. No need to open the caps unless the water is low (marked on the side of the battery). Be careful and use distilled water if topping up!

 

[Ingineer]

I left the CTEK charger on the 12 volt battery for about 8 hours. Green light hasn't come on yet. Stopped charging, voltage measured about 13.3 volts (but didn't wait 30 minutes yet to see where voltage settles). Is this to be expected? I didn't think it would take this long. Thoughts?

Did you disconnect the LEAF from the battery? It may be the parasitic loads are stopping it from entering the absorption phase.

-Phil

 

[RegGuheert]

Follow-up on my use of the CTEK charger. After I posted, went out and saw the green light on. Unplugged the CTEK, waited 30 minutes and checked the voltage - 12.95. Put the Leaf back on the CTEK for about 18 hours, unplugged it, waited an hour, checked voltage - 12.85. Let the Leaf sit overnite, checked the voltage - 12.53. I don't know if this means the Leaf used a bit of charge overnight, or if 12.53 (about what I got before using the CTEK) is the best my battery can do.

I've charged the LEAF battery twice within the last week or so. Here are a few data points:

- One hour after first charge: 12.75V
- One day after first charge: 12.65V
- Two days after first charge: 12.53V

- One hour after second charge: 12.86V
- After overnight following second charge: 12.68V

Note that these results were obtained with the EVSE unplugged from the LEAF. Were you plugged or unplugged for your test?

 

[Stoaty]

I've charged the LEAF battery twice within the last week or so. Here are a few data points:

- One hour after first charge: 12.75V
- One day after first charge: 12.65V
- Two days after first charge: 12.53V

- One hour after second charge: 12.86V
- After overnight following second charge: 12.68V

Note that these results were obtained with the EVSE unplugged from the LEAF. Were you plugged or unplugged for your test?

EVSE was not plugged in, but in response to Phil's inquiry, battery was not disconnected from the Leaf.

 

[RegGuheert]

EVSE was not plugged in, but in response to Phil's inquiry, battery was not disconnected from the Leaf.

Neither was mine disconnected from the LEAF. I suspect the Schumacher SEM-1562A charger that I use may have a higher current threshold to determine when to terminate the absorption phase of the charge. (Certainly, it must be somewhat higher than the 15 to 25mA that I have measured the LEAF drawing while sitting and not plugged in.)

 

[thimel]

Phil,

The CTEK charger you recommend (with 0.8 in the model number) has a big brother, model 3300, which can charge at a higher rate. That would be useful for charging my RV battery. Do you prefer the 0.8 simply because it is cheaper or is there some other reason like it having 6 charging modes instead of 4?

Also, is it correct that using the CTEK at the same time the EVSE is charging the car would be a very bad idea?

Thanks

 

[Ingineer]

Phil,

The CTEK charger you recommend (with 0.8 in the model number) has a big brother, model 3300, which can charge at a higher rate. That would be useful for charging my RV battery. Do you prefer the 0.8 simply because it is cheaper or is there some other reason like it having 6 charging modes instead of 4?

Also, is it correct that using the CTEK at the same time the EVSE is charging the car would be a very bad idea?

Thanks

All their units have at least 3 stages. The large units should be able to get the LEAF into absorption even with a load, so that's a plus. It won't hurt anything to use it while the LEAF is charging with an EVSE.

-Phil

 

[TimLee]

The 12V battery is covered for 100% replacement at no cost under the 3 year / 36,000 mile warranty.
Found this quote from Billy Hayes:
"Of the approximately 20,000 LEAFs on U.S. roads, Nissan dealers have replaced fewer than one percent of the 12V batteries both nationally AND in AZ, which I consider to be very low for both the nation and for Arizona.

And just to clarify, Nissan covers 100% of the cost of parts and labor for replacing the original 12 volt battery for all model year 2011 and newer Nissan vehicles for the entire term of the basic Nissan New Vehicle Limited Warranty, 3 years/36,000 miles, whichever comes first. Recently I read a post on mynissanleaf.com that suggests otherwise, but our policy is to cover 100% of the warranty repair cost for original equipment 12 volt batteries for the entire basic warranty period for MY11 and MY12 vehicles.

Separately, Nissan provides a warranty covering genuine Nissan replacement 12V batteries, which is also described in your warranty booklet. It provides that if your genuine replacement 12V battery becomes unserviceable during the first 24 months of service, it will be replaced without charge, including labor, provided it was originally installed in your vehicle by an authorized Nissan dealer. After 24 months, a replacement battery is provided at a reduced pro rata price that varies based on the age of the battery through 84 months, and the vehicle owner is responsible for labor charges.

I appreciate this opportunity to respond, and I will continue to keep an eye on this as my team and I do all other facets of LEAF ownership.

Billy Hayes"

http://www.mynissanleaf.com/viewtopic.php?f=4&t=11136&start=60#p265592" onclick="window.open(this.href);return false;

 

[thimel]

Many people have noted that the LEAF does not keep their 12V battery fully charged. As far as I know, no one has informed Nissan of the problem. Hence, I decided to carefully document the problem and inform Nissan so they can fix it. Below is the note I plan to give to my Nissan dealer. If anyone cares to suggest any improvements or some better way of informing Nissan, please comment.

My 12V lead acid battery never shows fully charged. I had you check the battery and it tested OK. It appears the charging system simply leaves it partially charged. This is bad for the 12V battery and will lead to its early demise from sulfation. As I explain below, the problem appears to be common to most LEAFs and hence is presumably a design problem. I would appreciate your confirming the problem in whatever way you see fit and then if a way to fix it is not clear, contacting Nissan about it.

I started by measuring the 12V battery voltage periodically. This was typically done the morning after it had charged to 80% during the night after being driven 30-45 miles during the day. It normally read between 12.04 and 12.15 V. A fully charged battery should read 12.6 V. To be sure it wasn’t just being discharged over night, I measured it two hours after driving (without charging). The voltage was 12.13 V. This indicates the battery was about 40% charged. I then measured it with a hydrometer. It read 1210 on one cell and 1220 on the 5 others. This corresponds to about 70% charged. I checked the hydrometer on my wife’s car and it read fully charged. I checked the DVM on a precision voltage source and it was reading 1.4% low, so all the numbers I give are corrected for that.

As a final check, I charged the LEAFs 12V battery with a battery charger. It started charging at a voltage of 13.8 V and a current of 4 amps. The current had dropped to two amps after 10 minutes and dropped to 1.5 amps after 50 minutes. It then kept charging at 1.5 amps until I turned it off after 1.5 hours of charging. I waited an hour and measured the voltage. It was now 12.70 V and the hydrometer reading was 1230.

Conclusion: the 12V battery is capable of being fully charged, but the LEAF does not fully charge it. I then waited a few days to let the battery get back to its normal, undercharged, condition. I monitored the voltage at the battery when the car was started. The voltage went up to 14.4 V, but in less than a minute had dropped down to 13.0 V. This is less than the float charge that chargers typically use. That is, it does very little to charge the battery. After a 15 mile drive, the voltage at the battery read the same 13.0 V while the car was still on.

Finally, at a meeting of the BayLEAFs user group, I measured the 12V battery voltage of 12 LEAFs which had been sitting for about two hours since last being driven. The voltages were: 12.3, 12.41, 12.31, 12.29, 12.34, 12.41, 12.40, 12.48, 12.28, 12.27, 12.09 and 12.27. While they vary, none of them indicates a full charge. This is why I think it is a design problem rather than a problem with my particular vehicle. It is highly unlikely that swapping parts will fix anything. This is why I respectfully suggest first confirming the problem with your own instruments and then asking Nissan for help.

 

[QueenBee]

Many people have noted that the LEAF does not keep their 12V battery fully charged. As far as I know, no one has informed Nissan of the problem. Hence, I decided to carefully document the problem and inform Nissan so they can fix it. Below is the note I plan to give to my Nissan dealer. If anyone cares to suggest any improvements or some better way of informing Nissan, please comment.

My 12V lead acid battery never shows fully charged. I had you check the battery and it tested OK. It appears the charging system simply leaves it partially charged. This is bad for the 12V battery and will lead to its early demise from sulfation. As I explain below, the problem appears to be common to most LEAFs and hence is presumably a design problem. I would appreciate your confirming the problem in whatever way you see fit and then if a way to fix it is not clear, contacting Nissan about it.

I started by measuring the 12V battery voltage periodically. This was typically done the morning after it had charged to 80% during the night after being driven 30-45 miles during the day. It normally read between 12.04 and 12.15 V. A fully charged battery should read 12.6 V. To be sure it wasn’t just being discharged over night, I measured it two hours after driving (without charging). The voltage was 12.13 V. This indicates the battery was about 40% charged. I then measured it with a hydrometer. It read 1210 on one cell and 1220 on the 5 others. This corresponds to about 70% charged. I checked the hydrometer on my wife’s car and it read fully charged. I checked the DVM on a precision voltage source and it was reading 1.4% low, so all the numbers I give are corrected for that.

As a final check, I charged the LEAFs 12V battery with a battery charger. It started charging at a voltage of 13.8 V and a current of 4 amps. The current had dropped to two amps after 10 minutes and dropped to 1.5 amps after 50 minutes. It then kept charging at 1.5 amps until I turned it off after 1.5 hours of charging. I waited an hour and measured the voltage. It was now 12.70 V and the hydrometer reading was 1230.

Conclusion: the 12V battery is capable of being fully charged, but the LEAF does not fully charge it. I then waited a few days to let the battery get back to its normal, undercharged, condition. I monitored the voltage at the battery when the car was started. The voltage went up to 14.4 V, but in less than a minute had dropped down to 13.0 V. This is less than the float charge that chargers typically use. That is, it does very little to charge the battery. After a 15 mile drive, the voltage at the battery read the same 13.0 V while the car was still on.

Finally, at a meeting of the BayLEAFs user group, I measured the 12V battery voltage of 12 LEAFs which had been sitting for about two hours since last being driven. The voltages were: 12.3, 12.41, 12.31, 12.29, 12.34, 12.41, 12.40, 12.48, 12.28, 12.27, 12.09 and 12.27. While they vary, none of them indicates a full charge. This is why I think it is a design problem rather than a problem with my particular vehicle. It is highly unlikely that swapping parts will fix anything. This is why I respectfully suggest first confirming the problem with your own instruments and then asking Nissan for help.

I think you may need to repeat your test with the batteries after they have rested with no load on them, so disconnect the negative terminal wait x hours and then measure voltage. After you charged the battery you only waited an hour, it takes much longer than that for the battery to settle into its resting state right? I'm not an expert at measuring lead acid batteries but I think this might be one reason for the low voltages, the batteries aren't actually resting when they are hooked up to the car.

 

[TimLee]

Many people have noted that the LEAF does not keep their 12V battery fully charged. As far as I know, no one has informed Nissan of the problem. Hence, I decided to carefully document the problem and inform Nissan so they can fix it. Below is the note I plan to give to my Nissan dealer. If anyone cares to suggest any improvements or some better way of informing Nissan, please comment.

I think Nissan is aware of the concern, but I'm not sure how many have formally documented the concern to them. Chelsea Sexton did raise the issue towards the end of the January 8th town hall meeting in AZ. The link I gave was the Nissan MNL response back to the question.
But they didn't really respond to the fundamental issue of the LEAF software not doing a proper job of maintaining the 12V battery. Just basically said failure rate of the 12V battery has been less than 1%. I think your write-up is well done. Voltage readings may be more definitive if all done a couple hours after disconnecting from the LEAF and being in a pure resting state.
You may want to review the advisory group thread, I haven't kept up with it, or possibly PM Chelsea Sexton (evchels) on how Nissan is addressing the issue.
As far as I know they haven't done anything to fix the problem yet.
May be something as simple as calibration problem with the 12V battery voltage monitoring that needs to be corrected. The discussions about the Android app for monitoring the LEAF seems to indicate that the 12V battery voltage reading is quite a bit off what you get with an accurate meter. I haven't bought the adapter yet, so I haven't done any monitoring.

 

[QueenBee]

The discussions about the Android app for monitoring the LEAF seems to indicate that the 12V battery voltage reading is quite a bit off what you get with an accurate meter. I haven't bought the adapter yet, so I haven't done any monitoring.

It's my understanding that this voltage is actually being read by the bluetooth dongle itself. From my experience with mine it's not even possible to calibrate my dongle because it jumps all over the place.

 

[JeremyW]

Hydrometer readings are the best, followed by open circuit voltage. Of course I agree with your findings. I've only seen one battery somewhat fully charged, the rest were not so good... :?

 

[Stanton]

My 12v battery sits at about 13.2v most of the time.
No, it's not the original lead-acid battery: I replaced it with a LiFePO a few months ago.

 

[LEAFfan]

The discussions about the Android app for monitoring the LEAF seems to indicate that the 12V battery voltage reading is quite a bit off what you get with an accurate meter. I haven't bought the adapter yet, so I haven't done any monitoring.

It's my understanding that this voltage is actually being read by the bluetooth dongle itself. From my experience with mine it's not even possible to calibrate my dongle because it jumps all over the place.

That's true, but I discovered that when using the EV dongle, it read the 12V exactly the same as my meter...12.6V with car off and 13.2V while running. I have no idea why the CAR CAN dongle is always a few tenths lower.

 

[ebill3]

NOCO Genius G750 - I don't know anything about it, but sounds pretty good for 17 bucks.

http://www.amazon.com/dp/B004LX3AS6...e=asn&creative=395093&creativeASIN=B004LX3AS6

 

[GerryAZ]

My 12-volt battery is doing fine and appears to be properly charged by the DC-DC converter. At rest, my battery typically reads 12.6 to 12.7 volts. I get these readings by releasing the hood when I start charging the car so I can measure the 12-volt battery voltage without opening the doors in the morning. If I unlock and open the door, the battery voltage will drop to between 12.1 and 12.4 volts due to the power draw of the dome lights and control modules that wake up. It takes several minutes after closing the door before all of the control modules go dormant and the 12-volt battery recovers to 12.6 volts. The float voltage is between 13.0 and 13.6 volts when the car is in Ready mode or charging, depending upon ambient temperature. The charging voltage is between 14.0 and 14.5 volts (depending upon temperature) for a few seconds after first placing the car in Ready mode or plugging in the EVSE before dropping back to the normal float voltage, much like a triple-rate marine battery charger.

My LEAF sometimes sits at the airport or my office for extended periods of time (over 3 weeks one time) and I have never had an issue--it is always ready when I return. I have never used a separate charger on the LEAF's 12-volt battery in the two years I have driven it and never had indication of low voltage. As others noted, the 12-volt battery voltage reading from the Bluetooth dongle and Android App fluctuates so much that it is of no use.

Gerry