This past week I replaced my battery, and I thought I would post up a DIY and some lessons learned from the experience. This is not a hard job to do at all, and probably well worth your while to do yourself. More on that later. In addition to what I am writing here, YouTube is your friend.
I have a 2011 535i base model, with a manual transmission. Also of note, I have the factory rear seat entertainment center. This is one of the very early build cars, with a build date of July 23, 2010. I have just over 71,000 miles on that car. As near as I can tell, this is the original battery. It is a BMW battery, and it is marked for 80Ah and 800 Cold Crank Amps (CCA) (see pics). My current service adviser says there is no record of a battery change. It has been ailing for several months. Symptoms include:
- a lot of slow starts this winter, when it was really cold. The car sits in the driveway, and overnight temps down in the 20s did not make it happy.
- a couple of no starts after being away for Christmas, and another time after sitting for a week after 13" of snow.
- Fuel economy was down probably 3-4mpg?
- after changing the battery, it is now obvious the car was running less smoothly (not rough though)
BMW wanted $300+ for a new battery, my local indy wanted about $280 for a battery. Then installation and coding on top of that. So, final price probably near $500. F that. So I also shopped the auto parts stores. There are only so many factories producing car batteries in the US. An "OEM BMW" battery at the dealer is just a regular battery with a BMW sticker on it. In the end, I bought a Autocraft Platinum AGM battery from Advance Auto Parts online. I did a little google-age, and came up with a 30% off code, too. They will deliver free to your door, or you can pick up at your nearest store. Price was $182, including a $22 core charge, so my final price is going to be $160 for the battery.
LESSON LEARNED: All the online sources I looked at showed a H9 battery as being a viable alternative. I initially bought one for the higher Ah and CCA, because of the rear seat entertainment center that gets run sometimes well after I have turned off the car. AN H9 BATTERY WILL NOT FIT IN A 535I. (see pics) I can't speak for a 528i or a 550i, but I assume they have the same floor as the 535i. Maybe the battery in the 550i is oriented differently? The manager at AAP, when I was returning/swapping the H9 for an H8 said his wife has a 7 series, and the H9 fits in a 7 series. Dunno.
To get at the battery, there are 2x 10mm nuts at the base of the flap that covers the little storage compartment. Lift the whole trunk floor up by the flap, then pull to the rear, and the whole ting comes out. For the remaining little storage compartment, lift the front end off the 2 bolts, the pull the whole thing towards the front of the car. The rear edge will slide out from under the trunk trim and you can lift it out.
Take a look at the picture below to see the battery with all the lining out of the way. There is a tie down bracket, which has 2x 11mm nuts. On the left edge of the battery is a metal bracket, on the right is a black plastic block with a 13mm bolt though it. On top of the battery, the two terminals are 10mm. The positive (red) terminal has a little plastic flap over it. There is also a plastic flap over the power distribution chunk in the middle. It covers another 13mm nut. There is also a metal band that clips onto the front and back of the battery. Reassembly with the new battery is the reverse. Personally, I was careful disassembling this stuff, and I wore rubber gloves.
Once the battery is out, you can see that there are three bolt holes for the black plastic hold down block on the right side of the battery (pic below, rotated 90deg left). My original battery (H7?) was in the middle hole. The H8 battery I ended up with is in the outboard (right) hole. Presumably you could fit an H6 battery?
The second important step to a battery change is registering the battery to the car. I found a Foxwell NT510 scanner on sale for $145. As far as I can tell, this is the same as the Schwaben scanner you might also see. Since that was probably about what I was going to pay the dealer to register my battery, seemed like a deal. And I should also be able to reset my service interval, read SES lights, etc. Works for my e46, too.
LESSON LEARNED: As you go through the battery registration process, the registration options are "I am replacing my battery with one of the same capacity" or "I am replacing my battery with one of lower/higher capacity". I assumed it would allow me to put in the new capacity (95Ah and 900CCA), but no. So then I made arrangments with my indy for them to put that info in on their system. Turns out, they can't/don't have any way to put that info in either. According to them, by telling the car it has different capacity, it will then figure it out. Whatever, my car is running better now.
Other side effects of this were my sun roof went wonky, but there is a thread on fixing that. Takes about 1min.
http://f10.5post.com/forums/showthread.php?t=730393
It also zeroed out my trip computer info, and the time and date. By the time I put the time in, it was already updating the date off GPS (I assume).
If you don't buy the wrong battery, then have to drive another car to Advance Auto Parts in the middle of the job, and you don't drive to the dealer for no reason, because they can't put in capacity data either, then the whole job is easily less than an hour. Total cost to me including scanner and battery is ~$315.
Picture 1 - a comparison of the H9 battery I initially bought to the OEM battery. Also an overview of the bolts and fittings
Picture 2 - a look at the hold down block on the right side of the battery
Picture 3 - the three holes you can use for the hold down block (rotated 90deg)
Picture 4 - a comparison the the H8 battery I installed to the original battery