[sarithf]

Hi all,

I changed my battery last week and I replaced it with a new Bosch one which had the stop/start logo on it. Therefore I assume it is a AGM type battery. However after driving short trips the last week I noticed that the stop/start doesn't work at all.

The old battery was a 80ah, but the one I replaced is a 75ah. Could that be the reason?
Please help.

Car is e90 318i 2011

[AM330i]

Did you get the battery registered after you installed it, was the old battery an agm type. You have to make sure you register and code to the battery you put in, otherwise it may not charge properly. looks like you installed a slightly larger battery so if it is coded for a smaller battery It may not charge your new battery correctly.

[sarithf]

Hi thanks for the reply. Yes it was registered after install
Also the old battery was an agm one.
The old battery was 80ah and new one is 75ah

[Bluewater328iT]

Not a good idea to put a new battery in with less ah, but that probably is not the issue. It should work OK if it is registered, so it must be some other issue with the stop start.

[sarithf]

I have a broken window warning light. Could this be the cause for stop start not working. Prob a stupid question but..

[mweisdorfer]

Originally Posted by AM330i

Did you get the battery registered after you installed it, was the old battery an agm type. You have to make sure you register and code to the battery you put in, otherwise it may not charge properly. looks like you installed a slightly larger battery so if it is coded for a smaller battery It may not charge your new battery correctly.

If your car never had start/ stop to begin with, it won't get this feature with a new battery that is made for cars with the start stop feature. E90's do not have start/ stop mode. F series do.

As far as your window? Is it the drivers side rear ? That's common for e90's. You can put a bandaid on it by resetting the window or replace the regulator.

Where did you get a Bosch battery? They are sort of hard to come by...

[david in germany]

Originally Posted by mweisdorfer

E90's do not have start/ stop mode. F series do.

European E90s do have start stop, Might check the location before you say things like that.

To OP, the start stop need the higher AH. Your battery may be to small. BMW recommends replacing with the same size or larger in this case. Also has the temperature dropped in your area? Was the car fully warmed up when the start stop didn't work? It could also be that the battery just isn't charged up enough for the start stop to work. Give it a few days of driving and see if it does end up working.

[sarithf]

Thanks guys. Yeah I'm in the UK and have stop/start.
Tempreture wise not a massive drop it's still autum.
I did a 2 hours long drive but still hasn't worked. Does being 5ah lower really affect this function? Maybe I should stick it to a battery charger and check.

[Sayek]

I have 2010 E92 320i with start stop. Its got a same battery as your old battery AGM 80AH 800CCA.
The start/stop function is very sensitive if battery charge is below certain level. I am in London and it still works after about 15min drive but i disable it as it does not really save much fuel but put wear/tear on the starter.

I am really scratching my head why you went for a smaller battery. People normally increase the battery capacity.
80AH is the smallest AGM used on E90. My friends car with idrive has 90AH. I have seen larger engines with idrive fitted with 110AH

I have not come across a BOSCH 75AH AGM before. I have seen 70 & 80
If that battery is 70AH and registered as 80AH well the car will think battery below minimum level for Start/Stop

[sarithf]

Originally Posted by Sayek

I have 2010 E92 320i with start stop. Its got a same battery as your old battery AGM 80AH 800CCA.
The start/stop function is very sensitive if battery charge is below certain level. I am in London and it still works after about 15min drive but i disable it as it does not really save much fuel but put wear/tear on the starter.

I am really scratching my head why you went for a smaller battery. People normally increase the battery capacity.
80AH is the smallest AGM used on E90. My friends car with idrive has 90AH. I have seen larger engines with idrive fitted with 110AH

I have not come across a BOSCH 75AH AGM before. I have seen 70 & 80
If that battery is 70AH and registered as 80AH well the car will think battery below minimum level for Start/Stop

Thanks for this..I'm going to try and get it replaced to a 80ah 800cca battery tomorrow. Will post the result.

[sarithf]

I just installed a BOSCH S5 A11 800A 80AH battery. The provider didn't make a fuss to swap with the old battery and boom stop/start just started working after running about 2 miles. Looks like the size of the battery was wrong in the end. Thanks for all your help to resolve this issue.

[david in germany]

Originally Posted by sarithf

I just installed a BOSCH S5 A11 800A 80AH battery. The provider didn't make a fuss to swap with the old battery and boom stop/start just started working after running about 2 miles. Looks like the size of the battery was wrong in the end. Thanks for all your help to resolve this issue.

Sweet! Thanks for the follow up as well. Someone may have the same issue one day and we can share this thread.

[Sayek]

Glad you got it sorted.Hopefully that battery should last you a few years.
My 2010 is still on original 80AH AGM battery. This winter will be the test
But I disable the start/stop so that may prolong the life.

[sarithf]

Originally Posted by Sayek

Glad you got it sorted.Hopefully that battery should last you a few years.
My 2010 is still on original 80AH AGM battery. This winter will be the test
But I disable the start/stop so that may prolong the life.

Everything is looking fine mate..thanks..my old battery survived 5 years and 35k miles :-)