Sics Consolidated Faded Moderns Thread - 2004 BMW Z4 2.2 & 2005 BMW 330i

[paulplom]

I'm not fiddling with the alternator output power.

Bottler!

[SiC]

Back again

Diagnostic tool said this was the voltage so the battery computer definitely can see it but is very low.

 
Checking that the battery computer is reading sensibly.

 
So it appears the auxiliary battery is dieing. I'm not entirely sure why yesterday it was showing 12.7v. Maybe because I had started it at that point and the battery computer started charging it. So it knew it was dead already but still made an attempt to be usable. It's starting to get near freezing now so presumably that and it sitting the last week was its final straw. 

Need to find a reasonably priced aux battery now. Possibly even main battery too. I'd rather have waited for the MOT to change these but that auxiliary battery is especially important with an SBC brake system as it provides emergency power for the braking pump if the main battery suddenly died. Kinda handy to have. 

[Eddie Honda]

Box of Swans, sir?

[SiC]

Box of Swans, sir?

Just because it needs a new battery?!

[SiC]

Found these on the internet. Interesting read. Confirms main battery should be AGM. 
I think originally from this document?
https://www.scribd.com/doc/54283365/Mercedes-Dual-Bat-System
 

[SiC]

This is currently the cheapest big named brand I can find that should fit:
https://www.ebay.co.uk/itm/223964856775

Main spec of interest is 12AH, 12V, AGM.
I think the magic size to search for is a YTX14-BS - but need to double check it's AGM as some appear to be Gel in that size too.

Other specs are similar, even CCA. Despite that not being important for this job. However this says the plates should be of similar construction - high discharge over high depletion.
AGM ready apparently means you just don't need to add acid to use.

Not marked as auxiliary but I think it should be fine for this job. Exide do a EK131 that is marked as for auxiliary battery use but appears to be far more expensive on what essentially seems the same thing. The cheaper AGM12-12 is marketed for motorcycles, the EK131 is marketed for an auxiliary battery on cars.

Going to order it and give it a go as I think it'll be fine. Much less ridiculous than £120 for a genuine Mercedes aux battery. Crazy expensive for such a small battery.

[Hooli]

I was going to say that sounds like the battery model in my HD, but you've spotted motorbike batteries already.

[SiC]

This is my current favourite now is this mingebag choice:
https://www.ebay.co.uk/itm/360848349225

Preferred over the previous one not because I prefer the brand, but because I prefer the retailer. Might get it Saturday if I'm really lucky with the courier.

CCA is lower at 150A than OEM 170A, but I think it'll make sweet feck all difference in this application. If anything it has a greater AH capacity. Not that any of these numbers could be entirely true either (who ever really checks?)

[Eddie Honda]

Main spec of interest is 12AH, 12V, AGM.

My spidey senses are tingling at the phrase "AGM READY"

It sounds like "HD Ready" on shite telly sets that were 720p

[SiC]

As I said above, AGM ready apparently means you just don't need to add acid to use.

From their booklet:

Screenshot_20231116-233651.jpg (53.4 KiB) Viewed 5701 times

I've ordered the cheapy Powerline now.