[Feanor]

Hi all, it's been a while! I've got a 2012 F30 320d and I've never replaced the battery since having it from new. It's very low mileage - about 35,000. I was away for over 6 weeks until last week and the solar trickle charger I connected to the OBD port doesn't seem to have worked; the computer was complaining about the battery being discharged when I started it up, and it's still not happy because I haven't done a run of more than 20 minutes in it yet.

Last time this happened it settled down after I'd driven for an hour or so - but I'm conscious the car is now only a few months away from being 7 years old. Will the computer tell me when the battery needs to be changed? Or does it need changing after a certain amount of time regardless? I don't want to swap it out prematurely but obvs also don't want to get stuck.

[obert]

I think they are usually good for 5 years and then it’s recommended to replace or at least be aware it’s getting old.

Once the battery discharges it needs to be put on a charger and not just jumped and driven. The alternator can only charge it back up so much and it does put strain on the alternator.

Seven years is pretty good on a battery so I would get it replaced. Unfortunately I have had mine replaced already.

[sspade]

Originally Posted by obert

I think they are usually good for 5 years and then it's recommended to replace or at least be aware it's getting old.

Once the battery discharges it needs to be put on a charger and not just jumped and driven. The alternator can only charge it back up so much and it does put strain on the alternator.

Seven years is pretty good on a battery so I would get it replaced. Unfortunately I have had mine replaced already.

How many years did yours last?

Any symptoms that led to replacement or was it voluntary?

Do you have part number of chosen replacement?

Did you register yourself?

[obert]

Originally Posted by sspade

How many years did yours last?

Any symptoms that led to replacement or was it voluntary?

Do you have part number of chosen replacement?

Did you register yourself?

I had mine replaced about a year ago due to a battery discharged warning. So about 5 years old. I just took it to the dealer and got robbed by them. It was in for something else I think and I just told them to take care of it as well.

[sspade]

Originally Posted by obert

I had mine replaced about a year ago due to a battery discharged warning. So about 5 years old. I just took it to the dealer and got robbed by them. It was in for something else I think and I just told them to take care of it as well.

LOL.

I'm approaching 5 years myself (May) so I know I'm about due. I guess I'll wait for the on dash warning then.

Planning to buy OEM replacement and register with BimmerCode.

[Hooded]

Originally Posted by sspade

LOL.

I'm approaching 5 years myself (May) so I know I'm about due. I guess I'll wait for the on dash warning then.

Planning to buy OEM replacement and register with BimmerCode.

Not necessarily, you could be good for a couple more years yet. I had a 10 year old car once that was still on its original battery!

[Soul_Glo]

Originally Posted by Hooded

Not necessarily, you could be good for a couple more years yet. I had a 10 year old car once that was still on its original battery!

All depends on how it is used. Twenty minute drives and the odd longer drive may not be able to drag it out. Low drain devices connected over a long time directly to the battery such as dash cams are not a good idea. Not using a battery tender etc. I also think quality of some brands has declined.

[Soul_Glo]

OP the straight answer is:

https://www.optimabatteries.com/en-u...mber-batteries

Whatever you do don't buy a Banner battery. They are shockingly bad and have a notoriously short lifespan. The quality varies so much from most lasting 2 years to a few making it 5 or more. I swear the quality has declined. OEM fit on many new BMW's is a Varta - which is a rebranded Bosch without full Bosch technology.

If you want to use a solar charger you need a minimum 40w. Many variables such as the panel being behind glass, hours of sunshine and, charger being unregulated etc. In fact it's safe to say an el cheapo solar charger without an MPC regulator will take more out the battery than it puts in or possibly overcharge and sulphate the battery.

[Pobsey]

I just replaced the battery in our e87 went with an Bmw one as managed to get a trade discount, the old one was 9 years old and was made by Banner! We noticed that the start stop had stopped working and the low voltage warning would come on after a short period with the radio on.

[330XDave]

OP give your car a good run before you buy a new one though you are probably ready. 32k in a battery heavy 320d in 7 years is nothing and it's probably had a lot more charging cycles than a higher mileage car.

[Watsey]

A low mileage car may also do lots of short journeys which do not sufficiently charge the battery. I'd recommend getting a good battery charger and running a full battery reconditioning cycle first.

Many Cetek chargers have a desulphication mode which can refresh the battery, plus bulk charge (to get the battery fully charged) and trickle charge.

I use this model :

CTEK MXS 5.0 Fully Automatic Battery Charger (Charges, Maintains and Reconditions Car and Motorcycle Batteries) 12V, 5 Amp - UK Plug https://www.amazon.co.uk/dp/B00FC42H..._W3mHCb68KWYWD

[Soul_Glo]

^ what he said. I have one of these and when the car hasn't been driven in two weeks then I stick it on charge. The key is to never let the battery drop below 12.4v. BMW actually have a charging schedule and calendar on when to tender your battery.

Once your battery has seen 12v or less it is as good as useless. It won't be as efficient or effective as once was and could leave you stranded.

You don't need an actual calendar to tender your battery but it's very thoughtful of BMW to have created one:

https://www.newtis.info/tisv2/a/en/f...ery/1VnYn17suS

I replace mine every 5 years as a rule. If a Bosch S5 is guaranteed for 5 years. I see no point being out of warranty at year 7 on the same battery.

[Isow]

I sold my 328i when it was 7 years 2 months old.
It was on its original battery.

[Hooded]

Originally Posted by Chelsea_Tractor

I replace mine every 5 years as a rule. If a Bosch S5 is guaranteed for 5 years. I see no point being out of warranty at year 7 on the same battery.

You must have money to waste? Why change a working battery at 5 years just because the guarantee is up, when it's possible it could last for a few more years yet.

[Soul_Glo]

Originally Posted by Hooded

You must have money to waste? Why change a working battery at 5 years just because the guarantee is up, when it's possible it could last for a few more years yet.

Brother Hooded. At the 5 year mark it is losing more of it's charge capacity. It's a risk I am not willing to take.

https://www.warrantywise.co.uk/blog/...ur-car-battery

For me it's about reliability.

[teaston]

Originally Posted by Chelsea_Tractor

Brother Hooded. At the 5 year mark it is losing more of it's charge capacity. It's a risk I am not willing to take.

https://www.warrantywise.co.uk/blog/...ur-car-battery

For me it's about reliability.

Don't you test it first though!? If it's still holding good charge then there's no need to replace it whatsoever!

[Soul_Glo]

Originally Posted by teaston

Don't you test it first though!? If it's still holding good charge then there's no need to replace it whatsoever!

For me. I load test it. I have a lot aftermarket kit on. Sub woofers, dash cams, tracker and, additional alarm... my battery has never lasted more than 5. The old man has always been caught out in year 7-8 and I think well if you had routinely replaced it at 5 then you probably wouldn't have had that problem. May be it needs to be a routine thing and BMW say every 5-6 years replace it. We have delicate cars with sensitive charge systems. It doesn't take much to throw things off kilter because the battery was worn. Nothing more embarrassing than being at Ascot and not having your battery able to start. Happened to me. Wife wasn't happy.

[Hooded]

Originally Posted by teaston

Don't you test it first though!? If it's still holding good charge then there's no need to replace it whatsoever!

This^

[teaston]

Originally Posted by Chelsea_Tractor

For me. I load test it. I have a lot aftermarket kit on. Sub woofers, dash cams, tracker and, additional alarm... my battery has never lasted more than 5. The old man has always been caught out in year 7-8 and I think well if you had routinely replaced it at 5 then you probably wouldn't have had that problem. May be it needs to be a routine thing and BMW say every 5-6 years replace it. We have delicate cars with sensitive charge systems. It doesn't take much to throw things off kilter because the battery was worn. Nothing more embarrassing than being at Ascot and not having your battery able to start. Happened to me. Wife wasn't happy.

Yes I understand if it has started to decrease in performance, but if it's still 12.6v or more then it's working just as well as a new battery.

[Soul_Glo]

Originally Posted by teaston

Yes I understand if it has started to decrease in performance, but if it's still 12.6v or more then it's working just as well as a new battery.

I wonder how many batteries at that age are even close to 12.6v

Resting voltage is not everything though:
https://batteryuniversity.com/index....id_batteries/2




Feel a forum poll coming on...

[Feanor]

Originally Posted by Chelsea_Tractor

Nothing more embarrassing than being at Ascot and not having your battery able to start. Happened to me. Wife wasn't happy.

Yes I can see that must have been awkward. Must have money to burn if you go to Ascot though!


Thanks for all the excellent replies everyone, very helpful. For those who keep their batteries for longer before replacing, what prompts you to replace them? I'd have thought modern cars would measure the battery's performance and have the computer provide a prompt.

The trouble with charging the battery is I have no driveway, only on street parking over the road, so connecting to a charger is difficult. I'm thinking of getting a jump start battery and tyre pump combination device and charging the battery from that - longer term it'd mean I don't need to faff around connecting the pump I have to the cigarette lighter, and it'd also mean I'm forced to regularly top up the jump start battery rather than forget about it in the boot and find it's self discharged when I need it.

The only thing that's making me hesitate is that the two I've found on Amazon don't look ideal - one is a dodgy looking Chinese thing and the other doesn't have a digital pressure display with pressure preset & auto shut off, which is a downgrade from what I have. The others I've found elsewhere don't have a USB charge input - I know I'll just lose a non-standard wall charger.

[Soul_Glo]

Side note. It was a wedding we were invited to where the bride burned through her parents pension pot.