[Supreme214]

Hi i need some help with battery replacement. My car is 07 335i (e90) and still has oem battery (90ah) and its time for a new battery. so i was thinking about duralast battery but i couldn't find ah on them and i also found some battery from (http://www.ntb.com/tires/Shop-Batteries.j) which shows ah 72ah 80ah and 100ah. is it ok to change battery ah from 90ah to 100ah or 90ah to 80ah?

[jadnashuanh]

While the vehicle can work with a smaller battery, you'll have less reserve as it gets colder (batteries lose a lot of cranking power when it gets cold), or as it ages. Bigger, if it fits, isn't a problem. But, if your vehicle is like the newer ones, you need to also have the dealer reprogram the computer so it knows the size and type of battery that is now installed...the computer adjusts the charging/max discharge scheme based on both the size, type, and age of the installed battery so it's not just throw a new one in...the computer will treat it more gently since it thinks it's an old one on its last legs, rather than a new one.

[gilly22]

Originally Posted by jadnashuanh

While the vehicle can work with a smaller battery, you'll have less reserve as it gets colder (batteries lose a lot of cranking power when it gets cold), or as it ages. Bigger, if it fits, isn't a problem. But, if your vehicle is like the newer ones, you need to also have the dealer reprogram the computer so it knows the size and type of battery that is now installed...the computer adjusts the charging/max discharge scheme based on both the size, type, and age of the installed battery so it's not just throw a new one in...the computer will treat it more gently since it thinks it's an old one on its last legs, rather than a new one.

^that pretty much sums things up right there. On a side note, I still wonder how the Optima battery line would work in our cars compared to other offerings (duralast, oem etc.). Most of the Optima's have much higher CCA ratings...wonder how well our cars would read/understand that info when they get programmed. Probably no issues at all I'm guessing.

[jhbrennan]

Originally Posted by gilly22

^that pretty much sums things up right there. On a side note, I still wonder how the Optima battery line would work in our cars compared to other offerings (duralast, oem etc.). Most of the Optima's have much higher CCA ratings...wonder how well our cars would read/understand that info when they get programmed. Probably no issues at all I'm guessing.

Optima's, while good batteries, are an odd size so you'll probably need a custom mount/bracket and the terminals aren't recessed so that may cause an install problem too - length of cable, etc.

[jadnashuanh]

I do not know when BMW started to use AGM batteries in their cars, but if you have an AGM, I highly suggest that you replace it with an AGM. IF the software does not offer that as an option, you should not, since an AGM needs higher voltage to become fully charged than other types generally available.

[ctuna]

Go bigger not smaller.

[djjasper]

I just replaced my 07 335i E92 battery. I had the original battery in my car too, which was the white (FLA) one. You should replace yours with an FLA if yours is white, otherwise you'll have to get it re-coded in addition to getting it registered if you go to an AGM battery. Check out my thread for the one I used:

http://www.e90post.com/forums/showthread.php?t=931443

[JacobT]

Just got a Duralast H8-AGM for my '08 e90 today. It's exactly the same size as oem. And it's AGM 90 AH, same as the original one. So the only thing I need to do after the installation is to register it with BMWLogger software.

[Supreme214]

Originally Posted by JacobT

Just got a Duralast H8-AGM for my '08 e90 today. It's exactly the same size as oem. And it's AGM 90 AH, same as the original one. So the only thing I need to do after the installation is to register it with BMWLogger software.

Was your battery agm oem? Or white non agm?
I saw duralast agm for about 170 with 92ah

[fun2drive]

My E93 had a 100AH white AGM battery. Key is if it is sealed or not. Sealed is AGM typically. If you have the right K+CAN cable you can register your battery yourself by visiting a thread in this forum by smooth. He has a free software that allows you to register your battery. I have used it and it works just fine.
Good advice to stay with the same AH and type (lead-acid vs absorbed glass mat (AGM)...

[E90_boostjunky]

I just went to auto zone told them I need a battery and the best and most expensive one for my car through it in and called it a day. No coding no programming. No problems its been 2 months.

[fazman]

Originally Posted by JinLee09

Hi i need some help with battery replacement. My car is 07 335i (e90) and still has oem battery (90ah) and its time for a new battery. so i was thinking about duralast battery but i couldn't find ah on them and i also found some battery from (http://www.ntb.com/tires/Shop-Batteries.j) which shows ah 72ah 80ah and 100ah. is it ok to change battery ah from 90ah to 100ah or 90ah to 80ah?

Check out the AAP or AZ website and look at the recommended batteries they suggest for your car. Once u find a battery u like, click on the specs tab to get more details about the RC and AH rating.

[Needbmwpartzz]

Originally Posted by E90_boostjunky

I just went to auto zone told them I need a battery and the best and most expensive one for my car through it in and called it a day. No coding no programming. No problems its been 2 months.

I'm confused!
I thought bmws battery needs to be coded to the car......can someone explain this
If someone buys a oem battery does that need to be coded or not.....or just different spec'd or brands need to be coded?? :

[Supreme214]

Originally Posted by fazman

Check out the AAP or AZ website and look at the recommended batteries they suggest for your car. Once u find a battery u like, click on the specs tab to get more details about the RC and AH rating.

Ya i did check az web and most of the battery don't provide ah.....

[djjasper]

They need to be REGISTERED, not coded if you buy an FLA to replace an FLA, or an AGM to replace an AGM. If you don't register it, the battery will still work but your car is not going to know that a new battery is in and will not take advantage of the capabilities of a new battery versus your old worn-out one.

[PichaDis11]

Originally Posted by Needbmwpartzz

I'm confused!
I thought bmws battery needs to be coded to the car......can someone explain this
If someone buys a oem battery does that need to be coded or not.....or just different spec'd or brands need to be coded?? :

Any battery will work with the car once its fits and is provided the proper voltage. Coding just helps the car to understand what battery it is and how to long cycles to charge/ discharge to help the battery last longer.

For a switch from a FLA (White casing) to an AGM (black) it is customary to have the car coded properly.

[JacobT]

Originally Posted by JinLee09

Was your battery agm oem? Or white non agm?
I saw duralast agm for about 170 with 92ah

I used the D-CAN cable to read the original setup. It showed AGM 90 AH even thought its a white FLA one. So I don't know how the factory setting was set before.

Yes, I paid $169.99 for the Duralast.

[Teufel_Hunden]

Bought an AutoCraft Gold Battery, 49H8 at Advanced Auto Parts. Seems to be working perfectly. Also had it registered at a local Indy for $45. Battery was $110 - bought it online with store pick up using a 30% off coupon code. I think it was TRT30.

[fazman]

Originally Posted by JinLee09

Ya i did check az web and most of the battery don't provide ah.....

More important than AH is the RC (Reserve Capacity)... i gurantee that both AZ and AAP both list the RC for their batteries in the "specs" tab. I personally prefer using the AAP website since it shows more useful info.

Formula for calculating AH

AH = (RC / 2) + 16

My car is coded for a 90AH charging profile and my original bmw battery has an RC of 160. Using the formula above i get the following:
(160 / 2) = 80 + 16 = 96 AH (so the car being set at a 90AH profile makes more sense to use rather than the 80AH profile or the 110AH profile). Makes sense??

[rotarypower101]

What are the eligible capacities for both a flooded and a AGM cell?
I cant seem to relocate a thread that specifies which are eligible via coding.

[Supreme214]

Originally Posted by fazman

More important than AH is the RC (Reserve Capacity)... i gurantee that both AZ and AAP both list the RC for their batteries in the "specs" tab. I personally prefer using the AAP website since it shows more useful info.

Formula for calculating AH

AH = (RC / 2) + 16

My car is coded for a 90AH charging profile and my original bmw battery has an RC of 160. Using the formula above i get the following:
(160 / 2) = 80 + 16 = 96 AH (so the car being set at a 90AH profile makes more sense to use rather than the 80AH profile or the 110AH profile). Makes sense??

Thanks for the formula! but how did you find out your oem battery had 160 rc? i thought it only provide ah for oem battery..

[NGEE]

I went to the dealer yesterday and bought an OEM replacement battery - $179. Register and done, no coding, no worries.