W221 battery question.

[G style]

Hi all,

Pretty sure I need to replace my battery well both batteries actually. Is there any way of checking which batteries should be fitted in from new? The reason I ask is that mine are both the same battery??? One under the bonnet and in the boot same numbers on same ah and same cca.

Is this right I would have thought that one would have been bigger than the other?
Thank you in advance.

 

[John Laidlaw]

My 230 had the same batteries

 

[G style]

Thanks for reply mate. When I've looked into new one that are non gen ones they seem to be taller by around 20mm not sure if the one in the boot will fit in the space I have? Anybody know what size will fit?

 

[davidsl500]

Should be an 019 battery I think - 190mm tall?

 

[G style]

Thank you fella. That's what the website's state when I look it up but the one that's fitted is 170mm and to get a 190mm in there would be a very tight squeeze lol if it will go in at all.

 

[G style]

Was thinking of giving a varta d52 a try? Anyone have any experience with these?
Cheers all.

 

[Botus]

If its an AGM one in there don't buy a new one. I did and its already given up. At 4 years old 10 k miles with regular recharging its given up. I may even put the 14 year old one back in as its in better condition.

Its the same on the bikes, it comes with almost nothing in it designed to reach 2 to 3 years and then give up. If you actually top it up enough to cope with the over charging modern vehicles force in, the battery it will be as good as new

Cut a bit around the sticker, peel off and unscrew the tops, put 150ml of distilled water in each cell and charge it. It will works just a well and a brand new one.

 

[G style]

Cheers I will give that a try and see how I get on. The batteries that are on are genuine merc ones and I think are standard wet ones. The varta d52 is indeed a agm one.

 

[Botus]

Std ones will say AGM and have a merc logo

depending on the age, what batteries you get changed. Early ones have a massive 25kg one in the boot and a normal one in the front. At some Point some went to just the front one.... if there was something in-between with a smaller rear I don't know

 

[G style]

Mine is a 56 plate and both batteries don't have AGM on that I can see and are both A0055411301. I like yourself thought one would have been a bigger one.

 

[Botus]

seems small, but if it has 2.... handbook is useless

 

[Rob76]

I just ordered a new one from MB Grangemouth, £147.5 delivered - cheaper than Halfords with a trade card

 

[Botus]

the same one the 221 takes, from the same place as above, that goes in the boot of my father's 211 is in the same place at just 18 months old...

they need to be topped up before you fit the brand new one....

 

[G style]

Thanks for the advice mate. I picked up some di water from halfords and topped up the front one today so will seehow that goes.
Cheers

 

[Botus]

as I said above in my 221 Genuine Merc AGM 25kg battery 4 years old 10k miles fully charged a week ago and tripped to maint mode and said its "weak". A week later went to put on charge as I wanted some support to scan diagnostics... 11.2v !!!

This is the same thing I had on the original, I limped on for a 18 months back them and thought OK, 11 year old battery buy a new one (the one above)....

So the old one, after a year doing nothing and half flat in the garage, I decided to throw it out and thought oh well lets see inside (as never seen inside an AGM one before), low and behold under the sticker 6 screw top lids... opened it up and found every cell had "bone dry tissue and black bits in-between". Topped it up and charged it. Comes back as "strong" and holds a charge.

That was 3 years ago, I've charged it once since and used as a slave to power 35w halogen lamp. Last used it for 9 hours without charge in the summer checked voltage still 12.6v !!!

6 months on after than and now four more winters on in a freezing garage, I'm thinking of topping up the one in the car... but the fight that is getting the lids off (due to some retarded tamper proof design) doesn't fill me with joy.

So I though I know the lids come out of the old one.... Oh yer !!! what a nasty design. Eventually got them unscrewed, and now second time round the lids are rather sorry to get out, but fully functional to screw back in. Yet again found 4 middle cells dry and the two outers, damper than I remember leaving them. Had some acid left from an old battery where I kept the stuff out of the non dead cells in a lead acid battery I was discarding, and now all gone topping up a third battery that's back to life.

So this 15 year old AGM battery not charged in six months, after a bit of acid added (100ml each in the middle ones) the tissue swells up covering the plates. Put the charger on and just like the BMW bike one I saved 2 months back, reported 13.2v straight away and tripped to maint mode after 5 seconds on charge...

Oh and the other day the GS 1200 AGM bike battery I topped up last winter, after it was suddenly dead ! is happy as it ever was and started the bike with gusto having not been on charge for 3 months this week.

 

[Rob76]

the same one the 221 takes, from the same place as above, that goes in the boot of my father's 211 is in the same place at just 18 months old...

they need to be topped up before you fit the brand new one....

So - said brand new battery went on to the CTEK for 24hrs. Upon coming home last night - i disconnected the charger, opened the cells and topped them off as advised. When i reconnected the charger 10 mins later the charger was back into bulk charge mode!!! The cells were dry looking and took maybe 50ml each until they all appeared wet: thanks for the heads up - it will be fitted later on