[TurboWeasel]

Originally Posted by Eddamoo

Hmm interesting... I also got an Exide EK950 from Scamazon in June 2023. It felt sluggish to start this morning after only being sat 2 days, and its -3C outside. I also had the 'Discharging when stationary' warning.

What is going on!?

Hmmmmm. That went away with my new Varta from Tayna. Cranks like a champ at -3.

This is why I sacked Scamazon Prime off last year. Not only because of the advert injection, but also because all of the top results are sponsored chinese crap now. I switched to ebay and get better products and service now, ironically, as it used to be ebay that was scam central!

There is definitely something about the genuine batteries isn't there. Fit and forget. Aftermarket ones don't seem to last.

[TurboWeasel]

Just had a look and the genuine 90AH AGM is coming in at £230 currently. It was closer to £300 when I looked last year, so maybe prices are stabilising. I don't think that is too bad tbh. Think I paid £180ish for the Varta using Number27s 5% discount code.

[Watsey]

I've deliberately held-off triggering a warranty claim on my battery, pending more testing.

Two days ago I completely disconnected the battery, and charged it again overnight with my CTEK.

Immediately tested the battery voltage => 12.78V.
Let the battery rest for three hours, and tested the voltage again => 12.49. Not too bad, but not the minimum of 12.6V that I understand equates to a healthy and fully charged battery.
Cleaned the battery terminals with wire wool and reconnected to the car.
BimmerLink shows the battery SoC as 99%.
Left the car unused on the drive for two days.
BimmerLink shows the SoC as 53% (which has been pretty typical). The dash cam is the only third party device which draws any current when the car is parked.
Started the engine, but it had an initial slow crank and just for a moment it felt like it wasn't going to start.
I've now ordered a battery test mater from Mr Bezos as it has some functionality which my multimeter doesn't provide i.e. min-max voltage when cranking, CCA analysis of actual versus specification, and charging ripple analysis (although I'm not expecting to see a problem here).

I still suspect that the battery health is degraded but would rather spend £40 to get a clearer understanding of the likelihood of this (plus having the benefit of the tester for future use) rather than immediately forking out, say, £200 but ending up with two batteries (if Tayna tests my battery as says that it's OK).

[xenon]

Does sound like a flaky battery.

[TurboWeasel]

Yeah it's the current that's key. A tired battery can still achieve the target voltages, but it's usually the heavy load current draw where it suffers first. Which typically isn't noticable over summer.

[xenon]

Originally Posted by TurboWeasel

Yeah it's the current that's key. A tired battery can still achieve the target voltages, but it's usually the heavy load current draw where it suffers first. Which typically isn't noticable over summer.

Absolutely - voltage can be misleading, as you say, but you can see a dead cell. But you're right - a voltage of 12.6V does not necessarily mean all is well.

[PG325]

I had a warranty claim with Tayna last year, they did pick and deliver a replacement with 4 days, luckily this was on a a classic E30 that sits in the garage 360 days of the year!

[Watsey]

I bought a dedicated battery testing unit, charged the battery fully with my CTEK (battery disconnected from car), let it rest for three hours, reconnected the battery, and then tested it.

The pictures speak for themselves, plus the fact that the engine wouldn’t even start a second a second time s few hours later. Not sure why a reading of 18% SoC equates to “good battery”.

I’m satisfied that the battery is FUBAR. New battery ordered today, and the existing one will be returned for testing and warranty replacement.

[TurboWeasel]

That looks like a good tool to have, and yep, it's over 30% down on grunt.

One thing I didn't check for on my new Varta is a production date. You get dates on genuine batteries but I don't recall ever seeing one on an aftermarket battery?

Makes me wonder if they sit around in a warehouse for months/years before they get shipped to customers?

The new battery is showing 82% state of charge after a 2 hour journey. That can't be right?!? Do these IBS modules just report nonsense?

[xenon]

Originally Posted by TurboWeasel

The new battery is showing 82% state of charge after a 2 hour journey. That can't be right?!? Do these IBS modules just report nonsense?

I would say that is fine. The BMS will not routinely charge to 100%, it's not good for the battery. It will level out at around 80% and then trickle, so I understand.

[TurboWeasel]

Originally Posted by xenon

I would say that is fine. The BMS will not routinely charge to 100%, it's not good for the battery. It will level out at around 80% and then trickle, so I understand.

OK thanks mate. Thinking about it, the only time I've ever seen 99% is just after registering a new battery.

[ade555]

Originally Posted by Watsey

BimmerLink only provides the option to Register a new battery. As per the comment from bishbosh I thought that coding a new battery would only be required if the type of battery was different, i.e. going from AGM to lead acid or lithium.

I just registered new battery from 90 to 95 and no problem since fitting but when bought mine hooked up to 10amp smart charge and been honest took well over 24h to finish. Start/stop is pernametly disable.