Shop has recommended new battery. Thoughts? (Resolved - Battery is good!)

[codys21]

Originally Posted by Hoppyumr

Can I ask why the bolts, 2 pulleys and tensioner are part of the replacement? Did the tensioner give and screw stuff up, or are they wanting to replace it because they aren't bmw shiny? It's just odd to have to replace pulleys, but you did say you didn't see anything of when giving a look at the track and that the belts even appeared to be there. Have you been able to see further whether the bells are actually bad? Just seems like an odd parts list.

What's odd to me as well is that the energy recovery appeared to show charging when it actually wasn't for you. I'm wondering if that display is not truly based off of power flow actually going into the battery and based more off of the engine knowing it isn't being throttled so it must be coasting; it's all part of the MPG calculation, so it wouldn't really surprise me if they fake the information based on computed assumptions.

Yea they did send a video overview of my car and I did see at least one belt was definitely not in good shape. I think they had both next to each other so not sure if both were destroyed or just one. They said they were pretty far down so they weren't surprised I didn't notice the belts when I opened the hood. Unsure if the pulleys/tensioner actually need to be replaced, either, and I'd agree the bolts are probably fine unless there was just that much tension/torque that destroyed the belts and also bent the other pieces. Either way, I did take it to a different shop so the dealership isn't getting any of my money (other than the diagnosis fee) but I should probably check with the indy shop to see if they agree the pulleys, bolt, and tensioner need to be replaced.

And I totally agree with your assumption on the energy recovery. The computer thinks the battery should be recovering energy because the car is coasting or braking but the computer doesn't register that there is no belt actually charging the battery.

[codys21]

Originally Posted by SD ///M4

So what was the final outcome? Were you able to get the battery charged with a proper charger? Or did you have to buy a new battery?

Note that even though I had the CTEK Lithium battery charger, I had forgotten about the reset button, so I jumped my car to get it started and then went for an hour-long drive which got it above the 8V self-protection point . I put the CTEK charger on the car after that to get it fully reconditioned and recharged. The battery has been fine since the original incident.

Originally Posted by codys21

Not sure yet actually. I called the shop my car is at (no longer the BMW dealership) and told them the battery is dead but that it could be revived by being attached to a lithium (CTEK or similar) charger for an extended period of time. They actually said they didn't have a charger like that but one of the employees apparently did.

Unfortunately, there was a delay in my parts being shipped. Two arrived Thursday but the other five aren't arriving until Monday morning so my car isn't actually fixed yet.

I'll definitely update this post once my car gets fixed and the battery situation gets resolved one way or another.

Alright so I've finally got my car back (it was finished Thursday and I picked it up Saturday). What happened was apparently one of the bolts/pulleys bent/broke and then my belt(s) went with it. The shop had my car inside all week and had it on a charger for at least part of that (not entirely sure how long but I did inform them it can take hours or a full day on the charger to get back to normal). They fixed the belts and pulleys, took it for a test drive, and everything seemed good to them. I drove it back two hours home and it seemed normal as well. Hooked it up to my new CTEK charger at about 7pm and at 10pm it was still at stage 2. At 7am the next morning it was already to stage 7. I used it for autocross that day (yesterday) and it worked like a charm (and didn't throw a belt again haha).

So, in short, BMW recommended a new battery after my battery had been dead for about 1.5 days. My car finally got fixed about two weeks later and the battery seems to have fully recovered without needing a new battery.

[Hoppyumr]

Originally Posted by codys21

Alright so I've finally got my car back (it was finished Thursday and I picked it up Saturday). What happened was apparently one of the bolts/pulleys bent/broke and then my belt(s) went with it. The shop had my car inside all week and had it on a charger for at least part of that (not entirely sure how long but I did inform them it can take hours or a full day on the charger to get back to normal). They fixed the belts and pulleys, took it for a test drive, and everything seemed good to them. I drove it back two hours home and it seemed normal as well. Hooked it up to my new CTEK charger at about 7pm and at 10pm it was still at stage 2. At 7am the next morning it was already to stage 7. I used it for autocross that day (yesterday) and it worked like a charm (and didn't throw a belt again haha).

So, in short, BMW recommended a new battery after my battery had been dead for about 1.5 days. My car finally got fixed about two weeks later and the battery seems to have fully recovered without needing a new battery.

I would keep an eye on it with the charger when you can. I don't have the CTEK charger (I have the NOCO) but it's odd to me that it would be stuck at an intermediate stage for that long. However at the same time you said you've taken it to the track, etc. so it seems to be holding and actually getting a charge from the car, so that's a a good/near thing, at least. Fingers crossed for you that it stays healthy.

[codys21]

Originally Posted by Hoppyumr

I would keep an eye on it with the charger when you can. I don't have the CTEK charger (I have the NOCO) but it's odd to me that it would be stuck at an intermediate stage for that long. However at the same time you said you've taken it to the track, etc. so it seems to be holding and actually getting a charge from the car, so that's a a good/near thing, at least. Fingers crossed for you that it stays healthy.

This is the first I've used a CTEK charger so maybe others know more, but I think it's supposed to be at stage 2 for a while. CTEK calls stage 2 the "bulk" stage and has the description of "charging with maximum current until approximately 90% battery capacity" and should be on this stage for a max of 10 hours. So, I think it's quite possible and normal for this specific charger to be on stage 2 for a while, especially if the battery was low when initially plugged in.

[TideMD]

Originally Posted by Hoppyumr

I would keep an eye on it with the charger when you can. I don't have the CTEK charger (I have the NOCO) but it's odd to me that it would be stuck at an intermediate stage for that long. However at the same time you said you've taken it to the track, etc. so it seems to be holding and actually getting a charge from the car, so that's a a good/near thing, at least. Fingers crossed for you that it stays healthy.

My CTEK charger does the same thing - takes a while to progress through the stages and reach level 7/8. Still have the original battery in 2016 M4 and never had issues with it.
The CTEK manual gives a nice breakdown of how long each stage can take to reach completion.

As far as the energy recovery aspect during coasting/braking - I think that system is separate from the alternator circuit, considering the point of the recovery is to allow a method of charging that reduces the overall work needed from the alternator. With that in mind, it would make sense for the iDrive display to indicate the recovery system is sending a charge back to the battery, even if the alternator isn't doing its job.

[codys21]

Originally Posted by TideMD

My CTEK charger does the same thing - takes a while to progress through the stages and reach level 7/8. Still have the original battery in 2016 M4 and never had issues with it.
The CTEK manual gives a nice breakdown of how long each stage can take to reach completion.

As far as the energy recovery aspect during coasting/braking - I think that system is separate from the alternator circuit, considering the point of the recovery is to allow a method of charging that reduces the overall work needed from the alternator. With that in mind, it would make sense for the iDrive display to indicate the recovery system is sending a charge back to the battery, even if the alternator isn't doing its job.

Thanks for attaching that image; I probably should've done that in my response haha.

But you think when I was doing those "slow" laps with coasting and braking that my battery was actually getting recharged? Because that system does not depend on the alternator/alternator belts like you mentioned? I guess that does make sense. I just don't know enough about cars and their energy recovery to know how that would work.

[TideMD]

Originally Posted by codys21

Thanks for attaching that image; I probably should've done that in my response haha.

But you think when I was doing those "slow" laps with coasting and braking that my battery was actually getting recharged? Because that system does not depend on the alternator/alternator belts like you mentioned? I guess that does make sense. I just don't know enough about cars and their energy recovery to know how that would work.

It was likely providing /some/ level of charge, but I can't imagine it would be enough to keep the battery at a healthy level. Likely only delayed the inevitable.

[SCS55]

Congrats on avoiding a new battery. Moving forward , your goal should be to get the Ctek to the float charge and let it sit there for a full day. Probably easier said then done, but that's what is needed to avoid any more issues. That, or take it for long highway cruises. (As noted in the manual)

[codys21]

Originally Posted by SCS55

Congrats on avoiding a new battery. Moving forward , your goal should be to get the Ctek to the float charge and let it sit there for a full day. Probably easier said then done, but that's what is needed to avoid any more issues. That, or take it for long highway cruises. (As noted in the manual)

Thanks. I haven't actually plugged the battery back in since I got it to stage 7 and ran the autocross event, but I can probably plug it in today since I'll be gone this weekend (taking the other car). It's fine to leave it plugged in for ~3 days, right? The manual says it'll stay at stage 7 (float) for a max of 10 days so I don't see a problem.

[TideMD]

Originally Posted by codys21

Thanks. I haven't actually plugged the battery back in since I got it to stage 7 and ran the autocross event, but I can probably plug it in today since I'll be gone this weekend (taking the other car). It's fine to leave it plugged in for ~3 days, right? The manual says it'll stay at stage 7 (float) for a max of 10 days so I don't see a problem.

I've left mine hooked up for over a week while out of the country. Also know of a few guys that have been away from home for months at a time and leave their CTEK unit connected.

One thing to watch out for is where the unit is positioned, as it can get fairly hot.

[SCS55]

Originally Posted by TideMD

I've left mine hooked up for over a week while out of the country. Also know of a few guys that have been away from home for months at at a time and leave their CTEK unit connected.

One thing to watch out for is where the unit is positioned, as it can get fairly hot.

Good point on the unit heating up, especially during the conditioning stage. I've left mine hooked up for 15 days once. No issues. I did notice when it finally gets to the 8th (last) stage, it's not nearly as hot as the initial stages.