Removing 12v battery to charge Leaf

[markrshort]

Hi all,

If I remove my 12-volt battery and charge/maintain it inside my flat, will the car lose any saved settings when I return the battery to the vehicle several hours later? Is this approach recommended?
I don't have access to main electricity as I am just using on street parking so using a trickle charger is not possible.
I'm wondering whether turning on/driving the vehicle everyday is enough to keep the 12v maintained or whether I need to invest in a battery maintainer.

Kind regards,
Mark

[LeftieBiker]

You will lose the settings, and that's a huge amount of work for the benefit! Your best bet is to replace the OEM 12 volt battery with a higher capacity AGM battery. The group number is 51R. The car should also do a better job of keeper the higher capacity battery charged. Fully charge it before installing it in the car. The cheaper, if less easy or likely to work fix, is to hardwire a good 12 volt solar battery maintainer to the 12 volt battery (the lighter socket is off when the car is off so you can't just plug it into that). This is assuming that you can park the car in the sun at least a few days a week.

[Learjet]

maybe you should look at a solar battery tender ....link...https://www.batterytender.com/solar-panels

[Nubo]

Given your circumstances, I'd just drive and see how you get on. Get a battery load tester that will show you the true health of the battery (not just voltage) and use it periodically so that you're aware of any degradation before it becomes a problem for the vehicle. If the battery does get weak I'd follow Leftie's advice and replace with an AGM. I think this approach is easier than repeatedly disconnecting the heavy battery and hauling it in and out of doors for charging episodes.

[GerryAZ]

Given your circumstances, I'd just drive and see how you get on. Get a battery load tester that will show you the true health of the battery (not just voltage) and use it periodically so that you're aware of any degradation before it becomes a problem for the vehicle. If the battery does get weak I'd follow Leftie's advice and replace with an AGM. I think this approach is easier than repeatedly disconnecting the heavy battery and hauling it in and out of doors for charging episodes.

+1

Just drive the Leaf and charge its traction battery as necessary. I drove my 2011 over 50,000 miles, 2015 over 80,000 miles, and 2019 over 17,000 miles so far. I have NEVER used an external 12V battery charger with them even though I routinely park for extended time at my office or the airport. When I replaced the OEM battery in the 2011 and later in the 2015 (with deep cycle AGM battery in each case), I installed the battery in the evening and plugged the car in to charge the traction battery overnight. The 12V battery is charged by the DC-DC converter whenever the traction battery is being charged, when the car is in "Ready" mode for normal driving, and periodically when the car is parked and completely turned off.

[LeftieBiker]

Just drive the Leaf and charge its traction battery as necessary. I drove my 2011 over 50,000 miles, 2015 over 80,000 miles, and 2019 over 17,000 miles so far. I have NEVER used an external 12V battery charger with them even though I routinely park for extended time at my office or the airport. When I replaced the OEM battery in the 2011 and later in the 2015 (with deep cycle AGM battery in each case), I installed the battery in the evening and plugged the car in to charge the traction battery overnight. The 12V battery is charged by the DC-DC converter whenever the traction battery is being charged, when the car is in "Ready" mode for normal driving, and periodically when the car is parked and completely turned off.

Your use case is common, Gerry, but it isn't the only common one. Some/many Leafs under some conditions don't do a good job of charging the battery. I guess it's possible that the OP is just being a bit OCD about this, but it's more likely that they have had trouble with a weak or dead accessory battery. Checking the rest voltage or getting a battery tester is the way to go if there is no problem now, but if there is one then it needs to be addressed.

[GerryAZ]

Hi all,

If I remove my 12-volt battery and charge/maintain it inside my flat, will the car lose any saved settings when I return the battery to the vehicle several hours later? Is this approach recommended?
I don't have access to main electricity as I am just using on street parking so using a trickle charger is not possible.
I'm wondering whether turning on/driving the vehicle everyday is enough to keep the 12v maintained or whether I need to invest in a battery maintainer.

Kind regards,
Mark

Mark,

If you are asking about the 12V battery just because there are numerous threads on this forum that note issues with the 12V battery charging algorithm, then I suggest you just use your car normally and test the 12V battery once in a while. As you can see from my previous post, there should be no need to routinely trickle charge your 12V battery unless there is a problem with your car or your use pattern does not keep the 12V battery charged.

If you think you have issues with your 12V battery now, then test it or get it tested and replace it if it is weak. If it is weak, then test the float voltage of the 12V system while the car is in "Ready" mode (ready to drive normally). The float voltage should be about 13 volts and will vary a little with ambient temperature (higher if it is cold). It should be between 14 and 14.5 volts immediately after turning the car on and will remain high until the 12V battery charging current drops below a threshold which causes it to drop back to the normal float voltage of about 13.

[gncndad]

markrshort: Without posting the model year, mileage, your location, and WHAT your problem is with the current 12V battery, the experts here are shooting in the dark.

How about some details?

[LeftieBiker]

If you think you have issues with your 12V battery now, then test it or get it tested and replace it if it is weak. If it is weak, then test the float voltage of the 12V system while the car is in "Ready" mode (ready to drive normally). The float voltage should be about 13 volts and will vary a little with ambient temperature (higher if it is cold). It should be between 14 and 14.5 volts immediately after turning the car on and will remain high until the 12V battery charging current drops below a threshold which causes it to drop back to the normal float voltage of about 13.

Have we ever seen a Leaf that has abnormal accessory system voltages while in Ready Mode? The issue seems to be mainly that when you plug the car in, the voltage will drop too soon from the bulk charge voltage of 14+ volts, and will quickly settle into the float mode of about 13 volts, thus not really recharging the accessory battery. Then, if you leave the car plugged in after charging ends, the accessory battery eventually gets drained. The test that will identify both chronic undercharging and an abnormal vampire drain is the rest voltage measurement, with the car sitting undisturbed, hood open, door closed, for at least 15 minutes. Anything under 12.4 volts indicates that the accessory battery is not even nearly close enough to 100% charge.

[markrshort]

Hi all,

Thanks for all this very helpful information. I've just got the car back from an independent specialist and he said the 12v was at 74% capacity when he put it on charge so it seems that my usage of the car(during lockdown) is leading to 12v drainage.
Will Leafs fault on startup with a battery that only kicks out under 13volts on float voltage?

In order to rule out a weak battery, I've ordered a cigarette lighter voltmeter so I will be able to monitor the volts to see if the float voltage drops below 13. If it does then I guess I will have to get an AGM battery(kicking myself I didn't do this when I last replaced the battery).
Can anyone recommend a specific battery in this case?

Thanks again,
Mark