atmoicmiata
Posts: 4
Joined: Mon Aug 19, 2019 9:46 am

Re: Changing the 12 Volt Battery

Mon Aug 19, 2019 4:27 pm

With the car off, my 12v battery measures 13v.
I'm good for now, right?
-stevei3

robthebold
Posts: 93
Joined: Sat May 11, 2019 5:09 pm

Re: Changing the 12 Volt Battery

Mon Aug 19, 2019 5:36 pm

atmoicmiata wrote:
Mon Aug 19, 2019 4:27 pm
With the car off, my 12v battery measures 13v.
I'm good for now, right?
With no load, all but the deadest of lead acid batteries appear fine.

alohart
Posts: 1920
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Changing the 12 Volt Battery

Tue Aug 20, 2019 1:58 am

atmoicmiata wrote:
Mon Aug 19, 2019 4:27 pm
With the car off, my 12v battery measures 13v.
I'm good for now, right?
13.0 V is higher than the resting voltage of a fully-charged AGM battery. If you measured this voltage shortly after shutting down your car, the battery's voltage was likely not the resting voltage and was slowly declining to its resting voltage.

As suggested, the resting voltage isn't a definitive determination of the health of a lead-acid battery.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

atmoicmiata
Posts: 4
Joined: Mon Aug 19, 2019 9:46 am

Re: Changing the 12 Volt Battery

Tue Aug 20, 2019 4:26 am

Good to know. Thanks all.
-stevei3

MoreliaViridis
Posts: 5
Joined: Wed Jun 28, 2017 11:14 am

Re: Changing the 12 Volt Battery

Tue Aug 20, 2019 10:26 am

So the 175 dollars when the dealer puts the battery in for 440 dollars is for registering. LOL what a rip off. My battery diminished because of the car sitting in non-use for a couple weeks, brought up a bunch of errors, locked the back wheels in the garage, locked the charge door, used the manual door opener, manual opener broke the brittle blue line, pulled the wheel well liner by removing a few screws, pulled the end of the blue deal which opens the door, plugged in the charger, charger got error message. Certified Pre Owned BMW got the car to the dealer but required a flat bed with skates under the wheels to get it on and off. News flash, CPO warranty doesn't cover much and no battery warranty. If anyone would like to see a list of other things you'd imagine the CPO dealer purchased warranty might cover and doesn't, here's the link. So when you're at the dealer and the sales guys are telling you how everything is covered, ah.......no it's not. https://cpo.bmwusa.com/Content/docs/BMW ... overed.pdf

User avatar
MKH
Gold Member
Posts: 523
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Changing the 12 Volt Battery

Wed Aug 21, 2019 6:20 am

As suggested, the resting voltage isn't a definitive determination of the health of a lead-acid battery.
To do a battery health test, you need to use a conductance tester.

https://www.youtube.com/watch?v=UIdDeQfaoSY
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

alohart
Posts: 1920
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Changing the 12 Volt Battery

Wed Aug 21, 2019 8:13 am

MKH wrote:
Wed Aug 21, 2019 6:20 am
To do a battery health test, you need to use a conductance tester.
Would that provide the same health determination as a battery load test?
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

User avatar
MKH
Gold Member
Posts: 523
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Changing the 12 Volt Battery

Wed Aug 21, 2019 9:12 am

Would that provide the same health determination as a battery load test?
Pretty much - both check the condition of the plates in the battery - though with load testing you normally get a "pass/fail", with conductance testing you get more of a 'current health-remaining service life' number.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

Return to “Problems / Troubleshooting”