Should I replace the battery?

[luke42179]

2016 M4, 21,000 miles. New car to me. Brought it in for valvetronic but Dealer says battery got as low as 36%, and so it should be replaced. Never noticed a battery issue. I drive only 10 miles each way for work and just read the charging scheme is inadequate, so I'm suspicious of their recommendation.

They want $1800. Independent says $1200. Should I do it, is the battery dying? or just take it home and start using the proper charger to keep the battery up?

Car is under factory warranty and they're "checking into it". Should the battery be covered?

[G4BR13L]

The battery should last 10 years/150k miles. Imho they should replace it free of cost. Down to 36% of what? How did they measure? What is the measured output voltage? Can’t it just be reconditioned? Smells to me like they want to make a quick buck out of your pocket.

Update: i looked in the technical training and here is what it says about the life cycle of the battery (LiFePO4):

The number of available full cycles for li-ion battery is 14 times higher than for a conventional lead-acid battery.

Conventional lead-acid: 350 possible charging cycles
Li-ion battery: 5000 pissible charging cycles

If the voltage falls below 8 V and the battery isolating switch opens, this becomes noticeable by a vehicle electrical system without voltage. Electrical functions are therefore no longer available. In this case the battery should not be replaced straight away as an initial measure. It is generally sufficient to recharge the battery. As soon as the battery supervision circuits detect a voltage over 10 V for longer than 2 seconds, the battery supervision circuits close the battery isolating switch again. The vehicle electrical system is supplied with voltage again. All electrical functions are available again. The battery is then charged again.

The battery only has to be replaced if the battery isolating switch no longer closes or the energy diagnosis specifies a replacement.

Refer to SIB 04 06 14 for more information.”

[RickFLM4]

Sounds ridiculous to me. $50/mo. for a battery? I agree on pushing for warranty coverage if there is truly something wrong with it. Then start going to a different dealer for maintenance.

[luke42179]

Very helpful information G4!

All electrical systems that I'm aware of were operating normally when I dropped off the car, unless you count what sounds to me like the Valvetronic issue (intermittent noise below).

My only doubt about whether to replace the battery now has to do with this from your post: "The battery only has to be replaced if the . . . energy diagnosis specifies a replacement."

Here's is exactly what they sent me to approve:

"CUSTOMER STATES THERE IS AN INTERMITANT NOISE WHEN ULOCKING THE VEHICLE FIRST THING IN THE MORNING. PLEASE CHECK AND ADVISE.
Recommend replacing battery with registraion (860cca)
Observations:
Found voltage supply faults in the vehicle, performed energy diag and found a day ago battery state of charge was at 36%. Battery is also about 3.5ys old
$1,814.51"

[G4BR13L]

Imho the battery should be reconditioned instead of replaced. Buy a BMW CTEK charger (for li-ion batteries) and connect the charger if you know you are not going to use the car for a couple of days.

And if replaced they should do so free of charge or at least give you a serious discount but don’t pay full price! I would pay maximum 500 euro or the price of a new battery $1200 / 10 (years) * 3.5 (years) = $ 420. Your dealer should work this out with BMW. I cannot imagine that after 3.5 years the capacity is down to 36% which is totally unacceptable. Maybe after 10 years but still 36% is ridiculously low.

If the sound you hear is coming from the motor compartment then it could be the electrical fuel pump what you hear and this is perfectly normal.

[MrSmartyPants]

For almost 2G I'd be recharging that shit.

You're also still within factory warranty and as someone else stated, the battery life is longer than normal lead acid.

[danchee]

Those short drives will drain battery more since you won't have enough time to recharge during that drive. I'm going out on a limb that the 36% is how much charge is left on the battery. Charging it back up should do it for you.

[luke42179]

I just spoke to the service advisor and they replaced the battery under warranty!

Didn't elaborate as to why - just that it shouldn't have been so low and they think it's the cause of the under-hood noise.

Sounds like throwing parts at a problem that they haven't really diagnosed, but hey, it's not my money.

I think that I'll be buying/using a battery charger/maintainer and taking my sled to another dealer for service. Three full days to figure this out is ridiculous.

Thank you gents for your replies.

[dzvero]

36% means you could have listened to radio with engine off. Why replacing it? It could be because you started car so many times in short amount of time, etc... Doesnt mean battery is bad!

[dzvero]

Do you replace your phone battery everytime the battery meter goes below 35% ? WT....f are thy doing with customers.

[G4BR13L]

We are mixing things here. A charge level of 36% is not the same as a capacity of 36%. Assume your new iphone lasts for 10 hours on full charge, after 5 years the capacity is 50% which means that a full charge now only lasts fir 5 hours.

[luke42179]

Correction: the dealer replaced the battery not under warranty, but under 'goodwill'. They said BMW warranty would not cover it. The SA couldn't tell me what was wrong with it, but they wouldn't have paid to replace it if it was ok and just needed to be recharged.

After they replaced it and I got the car back (heh) I told them that I drive only 10 miles each way to work. They told me that my driving habits will discharge the battery! Really, 10 miles isn't enough? It is for regular cars. Seems like a design flaw to me.

I bought the BMW trickle charger and hard wired the pig tails to the battery. SA and parts guy said that's fine - despite the fact that the battery instruction manual says charging the battery directly (vs through the points under the hood) will throw a code.

Anyone know about that?

[G4BR13L]

10 miles is more than enough for the battery but you might take your car for a longer drive on a sunday for example. Disable auto start/stop if it is enabled.

About charging the battery, this is from the manual and I would stick by it:

In the vehicle, only charge the battery via the starting aid terminals, refer to page 201, in the engine compartment with the engine off.

[Mendoteach]

I've charged mine with pigtails in the back a few times. No problems. Not sure why using the front locations would make any difference.

[danchee]

Originally Posted by Mendoteach

I've charged mine with pigtails in the back a few times. No problems. Not sure why using the front locations would make any difference.

It bypasses the computer tracking battery charge levels and lifespan calculator? If the battery is full and the computer thinks it needs charging, you'll end up over charging it thus shortening the life of the battery.

[Mendoteach]

Interesting. If I understand you correctly, when the battery charges on the charger–and doesn't overcharge (assuming you are using a battery charger made for the li-ion battery)–then when you drive the car and the computer thinks the battery needs charging and ends up overcharging the battery? Not that I don't believe you , but I find it hard to believe that the car doesn't check the battery voltage on start-up.

[FlyingLow78]

Originally Posted by luke42179

I just spoke to the service advisor and they replaced the battery under warranty!

Didn't elaborate as to why - just that it shouldn't have been so low and they think it's the cause of the under-hood noise.

Sounds like throwing parts at a problem that they haven't really diagnosed, but hey, it's not my money.

I think that I'll be buying/using a battery charger/maintainer and taking my sled to another dealer for service. Three full days to figure this out is ridiculous.

Thank you gents for your replies.

They think the low battery SOC is the cause for the Valvetronic motor ticking? I have a similar problem that started a month after I took delivery, and I drive my car at least an hour per day. I’m taking my car to the dealer this morning with 11 videos of the problem to see if they can dupe it. I’m highly skeptical of their assumption. Check out YouTube for other examples.

[danchee]

Originally Posted by Mendoteach

Interesting. If I understand you correctly, when the battery charges on the charger–and doesn't overcharge (assuming you are using a battery charger made for the li-ion battery)–then when you drive the car and the computer thinks the battery needs charging and ends up overcharging the battery? Not that I don't believe you , but I find it hard to believe that the car doesn't check the battery voltage on start-up.

The sensor keeps track of the number of times the battery is charged and all the relevant data points. These data points are used to determine how much voltage to use to charge the battery etc... That's what BMW says. Is it true? Who knows. Do you want to risk $1200 to find out? I don't, but if you're willing, I think everyone would like to know for sure!

[hellokitty]

Per my Bimmerlink, my battery now has 70% capacity. This number is after the CTEK has been left on the car overnight and shows fully charged.

At what point would I need to replace the battery? I am at the 5 year mark now.

[SCS55]

Originally Posted by danchee

It bypasses the computer tracking battery charge levels and lifespan calculator? If the battery is full and the computer thinks it needs charging, you'll end up over charging it thus shortening the life of the battery.

Originally Posted by danchee

It bypasses the computer tracking battery charge levels and lifespan calculator? If the battery is full and the computer thinks it needs charging, you'll end up over charging it thus shortening the life of the battery.

^^^This +1^^^

[instalher]

where is the battery in the f83?