[razfrankel]

I was at Costco today for my battery the salesman said H8 battery will that work for my car? I have 105AH AGM battery will I have to code it a different size?

[ctcarbonari]

You will have to CODE a different Ah rated battery.
You will have to REGISTER a new battery.

If your BMW originally had a 105 Ah Battery then I wouldn't downsize. It may work (even after coding & registering) but it begs the question: "Why install a weaker, different sized battery?"

I know the Costco near me doesn't keep the H9 AGM Batteries in stock.
The Dealership Parts Department is actually a good deal in my area. Their prices are very competitive and always have the 105 AGMs in stock for pickup. Plus you'll get the vent tube & plug.

Qsilver7 has made a lot of good responses to posts on this forum with pictures, explanations, etc.

Also, pay close attention if you end up buying an aftermarket H9 Battery as many of them do not carry a 105 Ah rating (they're 100 Ah) and would need to be coded as well.

[Surly73]

Originally Posted by razfrankel

I was at Costco today for my battery the salesman said H8 battery will that work for my car? I have 105AH AGM battery will I have to code it a different size?

So... I know this isn't the question that you asked, but...

Your screenshot shows a 27% state of charge. CHARGE, not health.

Why is your battery nearly fully discharged? Why are you purchasing a new one? "Discharging while stopped" message? "Startability limit reached?" Neither one of those calls for replacing the battery without further investigation.

For a long service life and for top performance, batteries like to be kept "fully" (>80%) charged at all times. At any state of charge <80% they are sulfating to some degree.

If this state of charge you show here isn't a fluke or special situation, I wager that there may be something about your usage habits, your charging system or a parasitic drain while the vehicle is off that is preventing your battery from being fully charged.

The Internet is full of BMW owners replacing batteries at the drop of a hat who don't need to, only to discover that nothing has changed after they forked over the cash for a replacement battery. You could be better off using the funds to buy a CTEK or NOCO Genius charger instead, depending on what's going on.

Just checking...

[razfrankel]

I am asking should I replace the battery to a different size and capacity H8 instead of H9. Interstate website said it’s the battery fits my car? When I start the car sometimes I have to hold the key next to the key on the wheel than start the car with the brake.

[Trian]

"Fits your car" means the dimensions of the battery, and usually the locations of the posts, will fit into your existing car battery compartment. Capacity is another question.

[ctcarbonari]

Originally Posted by razfrankel

I am asking should I replace the battery to a different size and capacity H8 instead of H9. Interstate website said it’s the battery fits my car?

Short Answer: NO, you should NOT.

As others have said in both the threads you've asked this question, you should not downgrade your battery. If your BMW originally came with a 105 Ah battery then you should replace it "in kind" with another one.

Check out www.realoem.com and you will see that there are various battery sizes originally provided for your car. The original size that your BMW came with depends upon the build & options. So, when you go to a third party application and it says an H8 will "fit", then technically they're correct; however, it is not the properly sized battery & capacity for which the electrical components of your vehicle was designed to work with. Will an H8 battery work? Probably. For how long tho & will you have any issues?

Without addressing any of the other comments regarding your 27% soc and diagnosing the state of health/startability of your existing battery (all of which I agree with, btw. Members are providing you good feedback) the simpliest and most straight forward approach to replacing your battery is to get one from your local Dealer Parts Department. They're usually very competitively priced.

Your existing OE Battery has lasted 11 years!!! Why not stick with OE for future? or at the very least replace with an aftermarket of the same size/capacity.

[Surly73]

Originally Posted by razfrankel

I am asking should I replace the battery to a different size and capacity H8 instead of H9. Interstate website said it’s the battery fits my car? When I start the car sometimes I have to hold the key next to the key on the wheel than start the car with the brake.

And I'm asking questions which might reveal that you don't need a new battery at all. And that whatever problems you're having are unrelated to your battery (and would still be present, even after paying to replace your battery).

Needing to hold your key against the steering column is NOT directly related to your vehicle battery. That function exists for the case where your KEY REMOTE battery goes dead.

If, for example, you are having a serious issue with your comfort access / keyless remote system in the vehicle, it may be causing your battery drain and your issues with starting.

You've already been given some advice not to downgrade the size of your battery below what was originally equipped. Furthermore if conditions are such that your larger H9 battery is at 27% state of charge, if you had a smaller H8 in the same usage conditions it might be dead already.