Changing the 12 Volt Battery

A good how-to:

https://youtu.be/lKRj8gLcsfI?fbclid=IwAR1WuvjLUO7P3SCErXg-hIkaSZ-zp3_rcOnAs8O9HUK3JTD4MaseJOhHuxg

Thanks for sharing! I might need it soon, battery is 40 months old now!

At 1.40, any idea what is Vent hose for ?

Secondly, would the car turn on after installing the new battery or does it have be registered first.

The vent hose is for the AGM battery to vent any gases on overheating of the battery during charging and such. My Camry Hybrid and Prius Hybrid have the hose as well.

I am also curious to hear from the OP if the car would start before registering. Also, could registration be avoided if a backup battery is connected to the terminals making sure battery power is always there thru the switchout, assuming the battery being replaced is weak but isn't completely dead.

Also, on the Toyota hybrids, the 12V does the minimal task of connecting the HV battery to the rest of the system on startup, apart from running some ancillaries while the car is off. Does the i3 battery do this (connection of the HV battery) as well?

Srivenkat said:

I am also curious to hear from the OP if the car would start before registering. Also, could registration be avoided if a backup battery is connected to the terminals making sure battery power is always there thru the switchout, assuming the battery being replaced is weak but isn't completely dead.

Click to expand...

I have disconnected our i3's 12 V battery 3 times for periods of 6 - 9 months each time. After reconnecting the battery, our i3 has always entered drive readiness state and performed normally, so I would expect the same when I install our new 12 V battery before registering it. I will decide whether to pay an independent BMW mechanic to register our new battery or whether to buy a tool that can register it.

Srivenkat said:

Also, on the Toyota hybrids, the 12V does the minimal task of connecting the HV battery to the rest of the system on startup, apart from running some ancillaries while the car is off. Does the i3 battery do this (connection of the HV battery) as well?

Click to expand...

Yes

WHen you register a battery in a modern BMW, there are two things:
- the type and size
- the age counter that needs to get reset when you add a new one

So, if you are just disconnecting the old battery for maintenance, when you reinstall it, there's no need to change any of those programmable items. But, when you install a new one, or the type or capacity changes, it will not get charged properly and its life will be shortened as a result. The computer adjusts the charging regime based on those parameters, so it would think it had an old battery in there, and adjust itself accordingly.

If you have a BMW battery, all of that can be done by entering the battery serial number, if I remember correctly. The BMW computer seems to just read the bar code, so it's easy for the tech.

Here is the Battery Registration process:

https://www.youcanic.com/wiki/register-bmw-battery

(note that the example shows a couple of registration processes, one using Carly - however the Carly App battery registration does not work with the i3)

Thanks Mark, Jim!!

Hi,
Does anyone know if the BimmerLink app will register an i3 battery?
(I sent a message to the developer, but have not heard back...)
Thanks

atmoicmiata said:

Does anyone know if the BimmerLink app will register an i3 battery?

Click to expand...

Apparently not.

I bought a Foxwell NT520 Pro that has been reported by other i3 owners to be able to register a replacement battery of the same type (i.e., AGM) and capacity (i.e., 20 Ah) but is not able to register a replacement battery of a different type (e.g., flooded cell) or capacity (e.g., 40 Ah).

Thank s Art.

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

atmoicmiata said:

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

Click to expand...

With no load, all but the deadest of lead acid batteries appear fine.

atmoicmiata said:

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

Click to expand...

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.

Good to know. Thanks all.

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/BMWCPOWhatIsNotCovered.pdf

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

Click to expand...

To do a battery health test, you need to use a conductance tester.

https://www.youtube.com/watch?v=UIdDeQfaoSY

MKH said:

To do a battery health test, you need to use a conductance tester.

Click to expand...

Would that provide the same health determination as a battery load test?

Would that provide the same health determination as a battery load test?

Click to expand...

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.