[Cebra]

Hello guys,

How should I go about installing my old battery back into my car?

I had drained my battery a few times and had a few rough starts. I thought maybe my battery was going bad so I swapped it and coded it with bimmerlink.

The battery I took out had almost no markings on it. So I didn't know what brand it was.




After running one of the codes on it (721112776446) I found this battery online Nationwide H8-720. Apparently it is rated for 760CCA.

I took my old battery to Canadian tire and got it tested, and apparently it is in pretty good health.

So, I want to install it back into my car. How should I go about it? If I just code it as a new H8-90 battery would that cause any problems. If yes, how else can I install this back to my car. I want to return the new battery I got and get a refund.

Thanks for your help!

[3PedalJake]

The coding only takes into account the battery ratings, it's condition is determined by the software algorithms. Just code it for it's AH rating.

[Cebra]

Thank you, I am imagining the capacity to be 90 Ah since it says h8-90 on the label. I couldn't find anything online. Any comments?

[3PedalJake]

Yes that's correct, size h8, 90 amps

[mainbearing]

I am not sure what 18/16 and Apr 17 on the bar code label mean. But that battery is old and has the white powder near the negative terminal. I would get a new Costco H8 AGM (95Ah) with 900 CCA. AFAIK, your car might not have the 95Ah-AGM option, if so code it to 90Ah. IIRC the BMW factory battery is 90Ah for the H8.

Costco's catalog shows 2006 330i uses H6. So I picked an 08 to find the H8 specs:
https://costco.interstatebatteries.c...option=2362318

[rararat4]

This is all fascinating to me. First off, I am aware that you cannot just plonk a new battery into an E90. You must do a battery reset. The purpose of the reset is that the car, ECU, or whatever feeds the right voltage to the battery, I guess, from the alternator. An old battery gets a higher voltage than a new battery. The computer changes the voltage based on the age of the battery. Failure to perform the reset fries the new battery because it cannot handle being charged by the higher voltage.

So, if what I said is correct, how would you then bring back the old battery? Can you resurrect the old battery state in the car's computer?

But in this thread there are a few other things I do not understand. First, coding the battery with bimmerlink. Second, getting an AGM battery. Just so happens that my car needs a new battery. I called an independent garage and they offered me an AGM battery. Because the capacity was not 90Ah I called BMW. Nope, my 2009 328i lci does not take an AGM battery but an old-fashioned lead-acid. Maybe it can take an AGM battery but BMW does not do that. Since it is a different type of battery, wouldn't that require a reset and some kind of programming to tell the car that the battery being installed, an AGM battery, is fundamentally different? So does bimmerlink allow for all that?

[marvinstockman]

First, as in most things, the Germans overcomplicate.

Second, the independent garage should be able to both sell you a battery and 'code' it to your car.

Or, and that's a big 'or', put in the exact same battery you're taking out, and you should be fine without programming. Your car will adjust to the new battery.

Finally, there's no magic to an AGM battery, as the old fashioned wet cell battery will work fine and certainly outlast your car.

Finally, finally, get something like what is shown in the below link and monitor your battery voltage.

https://www.amazon.com/s?k=cig+light..._ts-doa-p_7_13

[mainbearing]

I used a wet cell from Autozone before, but since Costco only carries AGM H8, that was what I have now. And the price is better than AZ's wet cell.