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Re: Keep a dying 12V battery going as long as possible

Posted: Tue Jan 25, 2022 1:29 pm
by LeftieBiker
jlv wrote: Tue Jan 25, 2022 8:02 am This makes sense as long as you are talking about doing this only while you wait for the replacement 12V battery (presumably 51R AGM) that you ordered to arrive, and it's not something you are suggesting people do all the time.
If this is stressing the battery enough to make a difference, then it makes sense to do it with a healthy battery - at least in Winter, when the seat heaters are often left On, and the HVAC blower is often set higher. In Summer, with fewer accessories left on, then just turning off the headlights before shutting the car off should suffice - if the battery is healthy.

Re: Keep a dying 12V battery going as long as possible

Posted: Tue Jan 25, 2022 1:33 pm
by nlspace
If her 2018 battery is really low capacity, then it might not complete a full 20 hr capacity test. But it would be interesting to hear how degraded it is.

FLA battery failures are really common these days with fewer trips and miles driven. Just last night i helped a neighbor with a jump start for this truck; he thought his alternator was bad, but it was putting out 68Amps into his weak 2 yr old battery. Sitting around without being driven or kept fully charged with a trickle charger, is a recipe for a dying 12V battery.

Re: Keep a dying 12V battery going as long as possible

Posted: Tue Jan 25, 2022 4:30 pm
by knightmb
nlspace wrote: Tue Jan 25, 2022 1:33 pm If her 2018 battery is really low capacity, then it might not complete a full 20 hr capacity test. But it would be interesting to hear how degraded it is.

FLA battery failures are really common these days with fewer trips and miles driven. Just last night i helped a neighbor with a jump start for this truck; he thought his alternator was bad, but it was putting out 68Amps into his weak 2 yr old battery. Sitting around without being driven or kept fully charged with a trickle charger, is a recipe for a dying 12V battery.
When the auto store does it's load test, the battery voltage will sag all the way down to 9V but it produces enough power in that short time that in theory, it would start a car according to them. Capacity wise, could you keep cranking on the battery if the car didn't start on the first or second try, probably not. I have tried to do a 20 hour test on it, it never makes it. Basically, it scores around 8AH of capacity, which is way below what the new battery rating gets (I don't remember if it was 31AH or 44AH for the OEM battery). I'm also running my test indoors where it's nice and warm, not freezing outside, so that probably offsets my numbers a little as well. I still keep the battery though, just in case it's needed for temporary service. :)

Re: Keep a dying 12V battery going as long as possible

Posted: Wed Jan 26, 2022 8:12 am
by gcrouse
I've still got the original 12v battery in my 2016 Leaf, should i be expecting it to start to die this year? Would it be worth asking the dealer to check it in April when I get my battery pack report?

Re: Keep a dying 12V battery going as long as possible

Posted: Wed Jan 26, 2022 8:17 am
by jlv
LeftieBiker wrote: Tue Jan 25, 2022 1:29 pm If this is stressing the battery enough to make a difference, then it makes sense to do it with a healthy battery
Sure. LOL.

Re: Keep a dying 12V battery going as long as possible

Posted: Wed Jan 26, 2022 8:23 am
by LeftieBiker
gcrouse wrote: Wed Jan 26, 2022 8:12 am I've still got the original 12v battery in my 2016 Leaf, should i be expecting it to start to die this year? Would it be worth asking the dealer to check it in April when I get my battery pack report?
5 years old is a good time to replace the 12 volt battery. You've gotten your money's worth from it, and the consequences of having it fail while driving, or when you have to have the car start for an important trip, outweigh any advantage from not replacing it. If you get a name brand AGM replacement, you will likely never have to do this again.