I'm having an issue with my R60 not starting occasionally, usually after taking multiple short trips. I replaced the battery a couple months ago with an Optima YellowTop DH6, which is 72Ah vs. the 70Ah OEM battery I took out. I went through the registration process via BimmerLink, but did not code a new battery size because 72Ah was not an option (only 70 or 80). Could this be part of the issue? Should I code it as 80Ah since it exceeds 70Ah, or is it close enough to 70Ah that this wouldn't matter?

Also, there is a squeal that seems to be coming from the alternator after the car starts in cold weather (approx. 45F or lower). It goes away after driving off or just a slight rev of the engine. I suspected the alternator might be on its way out as a result, so I took it to AutoZone for a test. The tech said it was only putting out about 12v and that he would expect 13-14v. I just want to confirm that this is what others would expect as well, before I go down the path of replacing the alternator. But it seems like with the squealing and low voltage this would be the part to replace.

Just looking to get feedback from anyone who may have experienced a similar issue or has more knowledge on the subject of the electrical system in these cars. Thanks in advance!

 

14v is healthy.

https://www.elreg.com/blog/how-to-te...the-right-way/

Cheers,

Charlie

 

So alternators in the R60 are computer controlled. They have a LIN connection (like a serial cable), and the computer will turn the alternator on and off.

So, 12v is not necessarily wrong. Do you have something like Carly where you can monitor the voltage while driving?

I'm also not 100% sure how AutoZone tests it, perhaps they have a computer connection?

That all said, wouldn't surprise me if it's dying, don't get it from the dealer. It's one of those parts that is stupid expensive. I went aftermarket.

 

Thanks for the replies. I stopped at the dealer for an oil change yesterday and had them check things out while they had the car. Wanted to wait until I had that info before posting back here.

When I went to AutoZone for the test, they just clamped right on to the battery terminals while the car was running. So there was no computerized test per se. That is where they were reading the 12v from the alternator. As suggested, I monitored the voltage from my phone via BimmerLink while driving. All of the readings I was getting were over 14v, which seems normal.

At the dealer, they initially couldn't reproduce the issue so I authorized an hour of diagnostics at $130/hr... They ran an initial test, which stated that the battery was about 75% charged, 12.36V, and only 649CCA (vs. the rated 800CCA). The test tool recommended charging and re-testing. They left it on the charger while doing the oil change, and then re-tested. This time it was closer to 80% charged, 12.39V, and 937CCA. So the battery tested "good", but the recommendation was still to recharge. They also said there was no issue with the alternator, as that tested out at over 14v both with and without load. The only issue they could see was the radio occasionally waking while the car was off, but they said that was within the norm, and to just make sure we don't leave the radio/dome lights on with the car off.

I should also mention that the car has a remote start installed. It is a "NuStart" (apparently similar to CompuStar as they share the same manuals) with a Drone Mobile module installed for phone-based controls. The dealer said my car is maybe one of three that they have seen with a remote start, but that it was installed correctly and is not causing any issues. This was one of my early concerns after getting it installed, and one of the reasons I chose the slightly larger Optima battery over the OEM.

So the theory now is that this battery sat around for a while before I bought it, and that it has never had the opportunity to reach full charge since it was installed. The recommendation from the dealer was just to fully charge the battery, so I went to AutoZone after and bought a 15A charger, which got it up to 100% in about 90 min. At this point, it's just a matter of waiting and hoping it doesn't die again. I'll also continue to monitor the voltages and battery charge level for a while, until my fear of a dead battery dissipates...

PS: In case anyone was wondering about coding the battery size, the dealer said that 70Ah vs. 80 Ah would make no difference in my situation (that is with a 72Ah AGM battery replacing an OEM 70Ah AGM battery). I explained that I changed it to 80Ah to test if that would solve my issue, and asked if I should change it back to 70Ah. They said I could just leave it and it wouldn't matter.

 

So, after fully charging the battery 2 weeks ago there were no issues with the car starting until today. The car sat all night and started perfectly fine in the morning. It was driven about 15 minutes and then sat in a parking lot locked and turned off for another 20 minutes or so. Upon re-entering the car, it would not start.

After jumping it and bringing it back home, I decided to do some further testing for parasitic draw but didn't notice anything unusual. I also figured that if the issue were parasitic draw, the battery would have been dead after sitting all night and not after sitting for a few minutes in the parking lot.

I am going to take it to a euro specialist shop this coming week to see what they think. Logically, to me it has to be either:

1. Some sort of sporadic parasitic draw that I was unable to detect
2. Something wrong with the alternator that the dealer somehow missed (or perhaps the alternator itself is not accurately reporting the voltage it is producing)
3. Some sort of issue between the alternator and battery, which results in the battery not being charged properly

 

The Euro specialist took all of about 10 minutes to diagnose the issue as an unstable battery. The battery is an Optima YellowTop DH6 AGM, and he said he has seen many issues with Optima batteries. He recommended I not only get the battery replaced under warranty, but also swap to a different brand.

So I went right to Autozone, where the battery was purchased, and asked for an exchange. They willingly gave me a Duralast Platinum H6 AGM as the replacement, which is also about $100 cheaper than the Optima.

I will see how things go with the Duralast and update this thread when I have more information.