[N8N]

OK, so last week I mentioned that my cruise control wasn't working one day... then it was working again, then yesterday I stopped at a gas station to get some chemicals ending in "ine" and my radio reset when I restarted the car. I'm pretty sure I know what this means but I went ahead and dug out my ScanGauge... it's saying that on a cold start voltage is fluctuating between over 14V occasionally dropping to 13.6 then right back up again. After shutting off car voltage at jump terminals under hood is exactly 12.0 according to my old Simpson meter. I'm trying to look at the "magic eye" but I'll be damned if I've *ever* seen any color on any of them, they all look black to me (going all the way back to the Delco batteries of the 70s.)

So, questions.

I do not have a battery load tester, but I'm assuming given the above (and that the car is a 9/2008 production vehicle with original battery still installed, I probably just need a new one, yes?

My battery is marked 90Ah, 720CCA, and it has two part numbers on it, S: 61 21 8 381 764 and AW: 61 21 8 385 398. So it's obviously a 90Ah, 720CCA battery but I do not see any indication if it is Exide or Douglas made nor can I find either of those part numbers anywhere online. Does it matter, or should I just pick up whatever the dealer has in stock? Both are same price, about $190 from Tischer.

Next question: realoem lists 61 21 7 639 053 as a 92 Ah Exide-made AGM battery. $240 from Tischer. I know that I would have to have the battery coded if I installed it; is there any real advantage to doing so? Normally I would just suck it up and pay the extra money for the AGM battery (I hate leaks; had to replace battery cables in my Jeep due to a cheap parts store battery, ended up going with a military surplus yellow top so that never happens again) but the stock battery looks surprisingly leak free. So, worth the extra money and hassle? Or not so much?

Alternately, I can get a 3 yr. warranty Duracell AGM battery from Batteries Plus for $170; is that a good option? It is 850 CCA and no Ah rating listed but I assume just code the car for the factory 92 Ah AGM battery? Tempted to go with that so I can "upgrade" to AGM and get a longer warranty as I understand that BMW only warrants new batteries for 2 yrs?

I see Sears DieHard Gold AGM for $162 as well, also 3 year/850CCA

Thanks!

[John 070]

I let the dealer do it for $280, whatever, blah blah blah

Now at the time, the battery was like $179, you're saying it's now $240.

I asked about AGM, and they said the battery would be $50 more, however, the coding is $140 more. So I stuck with original.

My thing is the battery probably lasts 6-7 yrs., so changing it out early and wasting a year isn't the end of the world. My recommendation is OEM original, although many claim they get Ever Start from Walmart, don't code, and it's fine.

I know it's only a battery job, but on this car I let the dealer do it for $280.

[N8N]

If it were $280 I'd do it - my local dealer wants $250 for the 90 Ah wet battery cash and carry, no registration no nothin'. I'm looking at probably $4-500 installed at either dealership, hence my looking for alternatives... I've reached out to a couple guys to see if I can get my car coded for AGM, just looking for experiences on the various options. In the meantime I'm going to pull the car in the driveway and set up my charger...

Follow up: I spoke to a good local independent (Sigy) who I haven't used before but came with a good recommendation from a friend... he said to buy an OEM battery, that he used to sell Interstate but he will buy batteries from the dealer for the newer cars because they "cause less problems." He also said that the wet BMW brand batteries for the late model cars "almost never leak" which is the reason why I have a preference for AGM, looking in the trunk of my car I do not see ANY leakage or corrosion, so the man might have a point.

So at this point I'm tempted to get the $190 wet battery from Tischer and let Sigy do the registration, $4-500 is stupid but I can probably get that done for under $250 or thereabouts if I install the battery myself. $190 for a recommended battery vs. $160-170 for aftermarket and more hassle (need actual coding not just reg.) might be worth the extra ducats if there really isn't a big advantage to going AGM. I'll be pissed though if it craps out after a couple years and I don't have the 3 year warranty

[TittoBlunt]

Check with RRT. If I remember correctly, they did my battery for about $300. That included an AGM battery and coding.

[ctuna]

Typically you get 6 years out of these battery's if you have a standard
driving profile. Which means your battery should have lasted till 2015.
If you don't you should consider a battery tender/charger.

Do you have any aftermarket devices such as a big stereo or do you not
drive the car for weeks and or only on short drives . Then you need
a tender/charger such as a ctek 3300 or better.

I got a Interstate MTP 49/H8 to replace the 90ah stock battery it has a little more in AH than stock but I wouldn't sweat a 10% difference in amp hours
(well at least to the high side)
its not going to be that specific. This whole battery charging system is a
fiasco that goes along with no dipstick. My e 46 didn't have one an the battery lasted 8 years.

[GoRomeo]

man feel bad for all you with these AGM batteries.

All of us with Exide (white in color) acid lead batteies are headache free seems like... mine lasted 8 yrs.

[ctuna]

Op has a lead acid battery
Almost nobody gets the other type.
And there are tons of people that have early death with the regular
battery.

[bob.g]

i just had mine done at the dealer today for 360 installed. they were gonna change me 275$ for the battery or 311$ installed (plus taxes), so i had them do it.

if you want to save a few bucks you could buy the battery from the dealer, one with exact same specs, then buy the cheapo k+dcan ebay cable, and get the free software to register the battery yourself. I would have done that but the local prices were decent so it wasnt worth the hassle. http://www.e90post.com/forums/showth...ight=bmwlogger

[GoRomeo]

Originally Posted by ctuna

Op has a lead acid battery
Almost nobody gets the other type.
And there are tons of people that have early death with the regular
battery.

You are probably right but lately lot of AGM batteries have gone death from what Ive seen here.

[N8N]

I don't need a full coding setup to register the battery? awesome. I do have cable. Tried to set up two different laptops for coding, got each one to the point where I could connect to the car and was about to load the daten files, then the HDD died on each one of them! I am having no luck with technology this year...

it's just about 5 years since my car was produced. I bought it used so I don't know how owner treated it. I did buy a CTEK 7000 last year and have topped up the battery a couple times trying to get as much life as I could out of it.

Today I charged the battery for about 2 hrs. but it was still not done and I needed to run some errands. I hooked up my ScanGauge while I was driving and voltage was constantly 13.7 or 13.8 at all times. Now it's charging again. One would think that if the system voltage was staying at 13.7 that the battery would be close to full at all times...?

Anyway if I have any more trouble I'll investigate that program in the link and/or RRT (never been there, probably ought to check it out though, they are local to me) also got a PM from another forum member that could possibly help, so thanks again guys

[ctuna]

My driving voltage is more like 14.5
And it like this in my other car to.
Monitored with at elm327.
Also I do have lead acid batterys so maybe that
would explain voltage differences.

[N8N]

Charger finished up about an hour ago. Took it off and let car/battery rest. Checked voltage, now more like 12.7VDC (as opposed to 12.0 when I checked it before.) Wonder what it'll say in the morning?

Interesting, but in an annoying way.

[N8N]

As of right now, voltage at the jump terminals is 12.2V. Car has been sitting since last night. So it looks like I've either got parasitic drain or my battery really is dead. Will the car go to sleep if I lock it with the trunk open?

[tony20009]

http://www.e90post.com/forums/showth...hlight=battery
http://www.e90post.com/forums/showpo...11&postcount=7

All the best and good luck.

[ctuna]

Why are you leaving the trunk open?
If its for charging you should be doing it from
the Engine Bay at the points designated in the manual.

http://www.bawarec.ru/manuals/3er/e9...3er-e90-12.pdf

[N8N]

was asking before I checked for drain, am assuming the best way to do that would be on -ive terminal. I have as you say always used the jump points under hood for charging.

[N8N]

was asking before I checked for drain, am assuming the best way to do that would be on -ive terminal. I have as you say always used the jump points under hood for charging.