12.6 to 12.7 isn't bad, but it isn't as high as it should be for a properly charged deep cycle battery, either. These batteries are being kept in a constant partially-depleted state for no good reason. Mine reads about 12.85, and I'm barely satisfied with that. This reminds me to check it again, though, to make sure it isn't trending downwards...
How's your 12v battery health?
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LeftieBiker said:
12.6 to 12.7 is ideal in my 100+ degree F climate--that is actually about what the starting batteries in my ICE vehicles are at this time of year. I will agree it is a little low for cooler temperatures. The original battery in the LEAF is not a deep cycle, but I will replace it with a deep cycle when the time comes.
Gerry
atlleaf
Well-known member
i get 11.7v and 11.8v before a start. is this bad?
LEAFfan
Well-known member
atlleaf said:
It's not very good. It may fail below 11.5. At rest, a healthy one will be 12.7, maybe 12.8. Since I ran mine down two times, it is now 12.4-12.5 at rest.
atlleaf
Well-known member
ok checked again today.. its 12.5v after a drive.. but in the morning it was 11.8v or so.
JeremyW
Well-known member
Check your water level! Could probably use a good external charge. Sounds pretty weak though.atlleaf said:
RegGuheert
Well-known member
First, note that you need to measure the RESTING voltage of the battery to make a reasonable estimate of the SOC of the battery. The LEAF will draw a not-insignificant amount of current from the 12V battery for many minutes after you shut it off (or open the door to pop the hood). You really need to let the car sit for 30 minutes to an hour with the hood up before making a battery voltage measurment. At that time, the LEAF only draws about 15 to 20mA of current, so the battery voltage will be close to a resting state.mikefox said:
Still, a reading of 11.7V says that your battery is mostly depleted, even if there was a small load at the time. The reason this happens in the LEAF is that the car does not keep the charging voltage at 14.4V long enough to fully replace the charge that was previously removed from the battery. Instead, it drops down to 13.1V very soon after the vehicle is started (or charging is stated, which also activates the DC/DC converter). At 13.1V, the battery will only charge if the battery is very depleted, perhaps 50% or more. This voltage cannot be used to fully recharge the battery. It is only useful for holding the battery charge up once the battery is fully charged.
My speculation as to WHY Nissan designed it like this is that the 12V battery in the LEAF spends about 5X as much time under charge as another vehicle driven the same number of miles. Because of this, Nissan was probably rightly concerned that the LEAF battery might be overcharged by simply maintaining 14.4V while the car is on as most other vehicles do. But somehow they have undershot and the LEAF undercharges the battery.
Personally, I have simply resigned myself to putting the LEAF 12V battery onto a battery maintainer every week or so to try to help it have a reasonable lifetime. I think I will go do that now...
Nubo
Well-known member
mikefox said:
One of the main problems comes when the car is left plugged-in while parked.
Now, when the LEAF is actually charging, the 12V gets a charge too. But when the car is finished charging, that's it.
If the car is left UNPLUGGED, then the 12V battery will be topped off every 5 days. But if it is left PLUGGED, for some reason the 12V never gets topped off. So if the main pack is already charged, the 12V will gradually drain if the car is left plugged in.
On top of this, to add insult to injury the car uses a lot more power when it is plugged in. This drains the 12V even more quickly.
Lead-acid batteries prefer to have shallow discharge cycles. However the tendency of the LEAF to drain the battery in the plugged-in scenario, leads to deep cycles.
Moral of the story -- once your car is charged, unplug it. Don't let it sit plugged-in for extended periods if it's done charging.
I have a voltmeter plugged into the 12v accessory port which I use to monitor my battery's voltage ( however, it is disconnected as one would expect during "Off Mode"). I am wondering if it could prove useful in letting me know in advance if I need to replace the battery before it fails to reboot the car. So one question it might be useful to know is "What is the minimum voltage needed to operate the Leaf?". Anybody have some useful info towards this end?
TomT
Well-known member
The only time it is likely to give you any useful data is when the car is in ACC mode since the 12V inverter will be energized at all other times when the port is active...
MikeD said:
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atlleaf said:
TomT: Yes, I agree that initially checking the voltage in "Acc Mode" before going to "Ready Mode" is of somewhat limited usefulness (and the battery must have strong enough to operate the Leaf up to that point), but the battery is under a small "reference" load at that point (dropping about 0.2v from "Off Mode") which is more useful than the low load "Off Mode" voltage, I think, when looking for a sign of battery deterioration.
However, I also get an indication of how discharged the battery is by how long the voltage stays at ~14.4v before dropping to ~13.1v after switching to "Ready Mode". I often discharge the battery by listening to the radio in "Acc Mode" for an hour or so, but so far it takes no more than 10 to 15 minutes to recharge the battery in "Ready Mode" (i.e. getting back to 13.1v) when I have done that.
Most ICE batteries are located in the engine compartment where they is subjected to high heat and vibration, so the Leaf battery should be at an advantage in this regard. I am interested if the typical Leaf battery failure will occur relatively slowly in a way that can be detected in advance (by my voltage monitoring) and allow me to replace the battery accordingly.
However, I also get an indication of how discharged the battery is by how long the voltage stays at ~14.4v before dropping to ~13.1v after switching to "Ready Mode". I often discharge the battery by listening to the radio in "Acc Mode" for an hour or so, but so far it takes no more than 10 to 15 minutes to recharge the battery in "Ready Mode" (i.e. getting back to 13.1v) when I have done that.
Most ICE batteries are located in the engine compartment where they is subjected to high heat and vibration, so the Leaf battery should be at an advantage in this regard. I am interested if the typical Leaf battery failure will occur relatively slowly in a way that can be detected in advance (by my voltage monitoring) and allow me to replace the battery accordingly.
RegGuheert
Well-known member
Just one detail here: I will say that the LEAF almost never "tops off" the 12V battery. Perhaps a better word to use here is that it "charges" the battery every five days. You can see this happening at day 19 in the plot in this post. Notice that the resting voltage increased from 12.4V to 12.5V and within two days the resting voltage had dropped below the level it was at before the five-day charge occurred. It did not increase to the ~12.7V one would expect to see if the battery had been fully charged.Nubo said:
Could it be that Nissan expected the car to be used for lots of short (2-5 mi) trips? Thus, they engineered for a short charge and expected that to happen 5-10 times per day? This is how I typically use my car and it works great. My July average is 2.6 mi/trip :lol: and my June average is 3.2 (I had a long 100 mi day in there :shockRegGuheert said:
. All of this even with bicycling to work. Unfortunately, I haven't checked my battery so I don't know if the voltage is any higher than others have reported. Pretty embarrassing.
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Perhaps someone thought that it was a good idea to apply the 80% long-life mode to lead acid batteries as well? ;-)
RegGuheert
Well-known member
I disagree. While testing the battery with a small load will tell you if it is already dead, You should note that letting a lead-acid battery sit around not fully charged will result in the lead sulfate hardening and the capacity being reduced. Put another way, if you want to see if your battery is deteriorating, then you want to see if it is sitting around not fully charged. If you want to see if it is already dead, then you can find that out by simply trying to start the LEAF.MikeD said:
If I thought the charging system in the LEAF were properly designed, I would agree with this statement. But since the LEAF virtually never charges the 12V battery to full, noting how long it remains at 14.4V only tells you how long the LEAF decided to charge the battery and nothing more.MikeD said:
Contrast that 15 minutes with the ~60 minutes that our battery charger holds the LEAF battery at 14.8V to charge it to full from where the LEAF often leaves it (which is often around 12.2V resting).MikeD said:
Agreed. The heat, in particular, is bad in many ways.MikeD said:
Your measurements of 11.7 tell you that your 12V battery is deteriorating due to hardening of the lead sulfate. This hardening happens faster in hot weather.MikeD said:
For comparison, I suggest you go out and measure the resting voltage of any other car in your driveway. Pop the hood and let it sit for 30 minutes to an hour befor testing. If your vehicles are like mine, they will all measure ~12.7V.
RegGuheert
Well-known member
Exactly!surfingslovak said:
Nissan's approach seems to be to charge the Li-ion battery to a higher SOC than is prudent for long life and the 12V battery to a lower SOC than is prudent.
Clearly there is an anti-battery conspiracy here!
RegGuheert: Thank you for your comments! I agree that it appears the Leaf's battery is not being charged in a manner to maximize its life. BTW I personally would be happy if the battery lasts 4 or 5 years (we shall see), but only 3 years I would be less so. Do you have a sense for how long the battery might last on average if it were optimally charged?
Do you think there may be other considerations, such as trying to reduce electrolyte depletion together with hydrogen gas generation? I don't recall checking electrolyte level being one of the periodic maintenance checks, so do you think if the Leaf were optimally charged it would likely require distilled water be added at some point?
Finally, do you see battery deterioration being a more or less gradual process of declining voltage at start-up (until it is eventually insufficient), or is there a significant chance of a sudden decline (like if a cell shorts out) which might not be anticipated in time by battery replacement?
Do you think there may be other considerations, such as trying to reduce electrolyte depletion together with hydrogen gas generation? I don't recall checking electrolyte level being one of the periodic maintenance checks, so do you think if the Leaf were optimally charged it would likely require distilled water be added at some point?
Finally, do you see battery deterioration being a more or less gradual process of declining voltage at start-up (until it is eventually insufficient), or is there a significant chance of a sudden decline (like if a cell shorts out) which might not be anticipated in time by battery replacement?
TomT
Well-known member
Very true. It charges for 5 minutes every 5 days... The 5 watt solar panel actually does a better job of topping off the battery...
RegGuheert said:
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