850i battery options

[BCinPhx]

Ok, been gone a while but searched quite a bit on batteries. I want to get some additional info from you guys on alternatives and modifications done. I am tired of buying monster battries. Thanks guys!

[cartoonz]

Best batteries are also the best deal... Exide Grp49/H8 batteries from HomeDepot @$119ea
Highest capacity, best warranty, $100 less than the competition. I've bought 16 of these things over the last 2 years... and no, none for the same car.

[mikae31]

These cars don’t need two batteries. Problem with two batteries is that they are hardly ever fully charged and this is bad for any battery. One good battery is enough and it stays in better condition because it gets charged better than two batteries.

Many has done single battery modification with no problems. There is absolutely no need for two batteries. I see only benefits of going to single battery.

[Belgiumbarry]

don't know @mikae31 , perhaps one is limited in Ah with only 1 batterie in one of the OEM places ?

I placed 2 new Bosch S4 007 72Ah... but one was bad and pulls the other one also down.
New set now for a year and no problems so far.

But i assume 144 Ah total is no overkill for a car like the 850....

don't know what's the most Ah batterie one can place in one side ?

[rogbmw]

I have used several sets from Walmart with excellent results. Plus, if I remember correctly, they have a 3 year free replacement warranty.

[masbury]

I've been using "blems" from Interstate. They are cosmetic blemishes only and the huge H8 batteries are $89.95. I also get a military discount that knocks another 20% off that price, so (I think) they are the cheapest around. The Interstate shop near me told me that H8's are not that popular so they usually have "blems" on the shelf. Have bought 8 in the last 2 months. Tis the season...

[mikae31]

don't know @mikae31 , perhaps one is limited in Ah with only 1 batterie in one of the OEM places ?

I placed 2 new Bosch S4 007 72Ah... but one was bad and pulls the other one also down.
New set now for a year and no problems so far.

But i assume 144 Ah total is no overkill for a car like the 850....

don't know what's the most Ah batterie one can place in one side ?

There is nothing so special in 850, that it needs two batteries. For example e32 750 and e38 750 only uses single battery. So, why does e31 have two? My guess is, that it has something to do with weight distribution. The electrics in e31 works just fine with single 95-110 Ah battery and this also stays in much better shape.

If you have two batteries and they aren’t equally charged, the weeker one stresses the other and the result is bad batteries. You CAN use two batteries but you should make sure that they get charged equally and are charged full every once in a while. Still, no need to use two. Just money spent to something these doesn’t need.

[bdiefAZ]

H8 AGM single battery conversion

[Belgiumbarry]

There is nothing so special in 850, that it needs two batteries. For example e32 750 and e38 750 only uses single battery. So, why does e31 have two? My guess is, that it has something to do with weight distribution. The electrics in e31 works just fine with single 95-110 Ah battery and this also stays in much better shape.

If you have two batteries and they aren’t equally charged, the weeker one stresses the other and the result is bad batteries. You CAN use two batteries but you should make sure that they get charged equally and are charged full every once in a while. Still, no need to use two. Just money spent to something these doesn’t need.

perhaps also because the aux heating option.... (which i removed.)

[BCinPhx]

Thanks guys...fast response and good info. My last post disappeared...the additional discussion links vanished. Thanks again...Bill

[PabloRock]

I have used several sets from Walmart with excellent results. Plus, if I remember correctly, they have a 3 year free replacement warranty.

Yes, these will be my next batteries. I bought a cheap one for my 93 Saab and less than a year later it was dead (the brake light was stuck on and drained it dead). Back to Walmart, new battery, no questions asked. The size for the bimmer has a 3 year warranty. My plan is to return them every 2.9 years. (my walmart doesn't have an auto center, so they didn't check it. an auto center walmart may actually test).

[cartoonz]

I'm telling you, the Exide Grp49/H8 batteries are Home Depot are the best deal you'll find.

[acheson850i]

agreed no probs with "Wallmart" equivalent. I think they are Johnson Controls batteries good to know about the Homedepot batteries too....course if I had a bucket load of moohlah I wouldn't be on this forum posting about batteries!

[Stantz]

I went with a single AGM type battery from NAPA. I like the AGMs because I find they’re a little more forgiving when I forget to hook up my battery tender.
I had lead/acid batteries, one of which leaked and messed up my nice, clean battery compartment.
It looks like those Exides aren’t available everywhere: I’m outside Seattle and the website says “unavailable”. $119 is a pretty darn good deal.

[Dr. T]

Roger, which battery model from Walmart? Just look for H8?


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[idfotou]

I just converted to a single H8 AGM battery from Autozone last month. Works great (THANKS Brian!).

[PabloRock]

Roger, which battery model from Walmart? Just look for H8?

I'm not Roger, but yes, the H8 should fit just fine (plus it's Walmart, so they take anything back).

[ltbrett]

The discussion on which brand batteries to buy is somewhat irrelevant as most batteries in the US are made by Johnson Controls and rebranded. If not, they are made by Exide or East Penn. That's about it.

Oh, and I too went for a single H8 from some generic source after getting great results from two R34 Optima's.

Brett

[Dr. T]

The H8 does not fit on the drivers side. Seems like it’s too long and slightly too tall. I currently have BMW 61-21-7-567-182. They are smaller and less tall. What group is this?

[72tpik5]

I'm using a single H8 AGM from Walmart. Installed on the passenger side, I am planning to mount amplifiers on the left side.

[cartoonz]

The H8 does not fit on the drivers side. Seems like it’s too long and slightly too tall. I currently have BMW 61-21-7-567-182. They are smaller and less tall. What group is this?

It does fit... but you have to loosen the jack clamp to get it in there. It is absolutely not too long.
You may also find your battery tray does not have a nut already mounted on the hole for the clamp... find an appropriate nutsert and viola!

[Dr. T]

Yeah, but there was also a metal bracket in the way in the rearmost corner even though I did have the screwhole for the clamp.

Did some more research and returned the H8’s for 2 H6’s and they were a perfect match for the OEM’s that were dated 2010. The H6’s felt like they were 1/2 the weight of the H8’s...

[72tpik5]

It looks like an H6 weighs 39 lbs, while an H8 AGM weighs 61 lbs. So the H6 weighs about 2/3 of the H8 AGM. So the fun math states that by going to 1 H8, I gained 1.5 horsepower. And I saved $150.00. Works for me.