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2000 540iA M Sport
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Discussion Starter · #1 ·
Car: 2000 540iA M Sport
Mileage: 231K
Work Done: What HASN'T been done? (I'll explain if need be)
Battery Date: The shocker...It's stamped 13/10 (Genuine BMW Battery)

I've been reading till my eyeballs were bleeding, and I was looking for a general consensus on my aged battery (or a "uhhh, replace it now"). The car has no problems starting, driving, electrical load bearing, or anything...honestly drives pretty solid. About 3 weeks ago, I got a "Engine Failsafe Prog" on my display (w/ High Cluster).while just driving around town. Car seemed completely normal as i scooted home. No battery light, nothing different (sound, driveability, etc.)...just increased blood pressure. When I got home, restarted the car, no message. So I took it for an hour "country road drive" (about 40-50mph) parked it without any message. (OBD/DME code scanned with Foxwell NT510 Elite...came with the car...no new codes)

Metered the battery at the terminals after the drive:
@ Idle (550-600RPMs): 14.24V
@ Ignition off: 12.45V
Test 09: 13.9/14.0V @ Idle (550-600RPMs) ... 14.1/14.2V @ 1800-2000RPMs in 5th gear (Auto)

The next day and following days (for 3 weeks), I've been monitoring the battery voltage (at the terminals) after sitting roughly 12 hours and it's always between 12.3 and 12.45. From what I read, 12.4-12.6 is 75% Charge and 12.2-12.4 is 50% Charge. Test 09 always yields posted numbers above while driving. Alternator replaced 8/2017. The previous owner was a BMW dealer tech that owned the car since 2013. I have a stack of receipts thicker than the owner's manual. I realized, that day I only drove the car for about 20min of runtime and start/stop 4 times in that period, maybe that was the problem? A sign that the battery is starting to have difficult recovery after a hard drain?

I guess, this long story short, should I just eat it and buy a new battery? I don't want it to take the alternator out. Also, from information here, my OEM black battery is AGM (OEM white is non-AGM). If I stay with an AGM, I shouldn't need to register it, correct? (Also read IBS was introduced in E60 models) If I have to, should I trickle charge the battery to 100% so the DME recognizes it's full potential on first system check?
 

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What Speed Limit?
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YES, replace it. Otherwise you'll wear out the alternator. And no, there's no registration for E39 batteries. Plug-n-play.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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20,697 Posts
YES, replace it. Otherwise you'll wear out the alternator. And no, there's no registration for E39 batteries. Plug-n-play.
Load does not wear any alternator. The maximum AGM battery charging rate is 4 Amps. A BMW alternator is probably rated at 180 Amps.

An Intelligent Alternator System only charges the battery on overrun - trailing throttle or alternator spin-down on its sprag clutch. AT ALL OTHER TIMES THE ALTERNATOR IS ONLY MAINTAINING ACCESSORY LOADS.

Get a proper AGM battery CHARGER and charge IAW the charger manual and your BMW owners manual frequently and regularly. I use a CTEK 4.3 MUS weekly for about 5 AH - 10 AmpereHours.
 
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I agree with Cookie Monster. An alternative could be to buy a battery charger and see how the battery behaves. One of the best automotive service purchases I've ever made.
 

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Why not just let it die, and put the car on a hook. That way, you'll have maximized the life of the battery. It won't be convenient, but, hey.
 
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I am not surprised by your battery life.
Keep the car out of extreme temps and keep it reasonably charged and 8 yrs is not unheard of.

I have battery life of 8 years twice with my non-AGM batteries.

I would get a new one, but I would not by an AGM battery. They are not bad, but are generally not worth the premium over wet batteries .
 

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Replace it, IMO. If you get one from BMW, it'll be about $500 or you can buy an AGM from RockAuto EXIDE MXH8L549 AGM; BCI Group: 49; CCA 850; 160 Reserve Capacity for $189.79 + shipping (they'll ship AGM ones) or a
DieHard Platinum AGM Battery, Group Size H8, 900 CCA from Advanced for $220. Don't get stranded waiting on the old one to go dead. It's cause other electrical issues with electronics
 

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AGM batteries require a higher voltage to fully charge them So I’d just but a conventional lead/acid flooded cell battery.
My last NAPA Legend battery lasted 12 years using a smart charger maybe once a week or when I thought of it.
 

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Napa Legend, best battery for the money. Bought one for $112.00 about 2 years ago.
That was a great price- even then.......today it is $150 + 18 core
I like the Everstart Maxx from Walmart...with a fresh date code.

I have seen Exide's at Home Depot (which are cheaper) with date codes more than a year old
 

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Could his $112 price be because the 528 uses a different group battery (lower CCA) than a 540?
I also paid about $150 for mine Last summer.
The HD I frequent has a large display rack of Exide batteries, I never see anyone buying or looking at them.
 

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It was Oct. 2019, $112.00 sale price, shopped around and found what I wanted.
Napa Legend wet cell battery
Group #49
900 CCA
Currently priced at $149.99 which I think was the same price 2 years ago (non-sale price) of course.
 

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Wow, big markup over the border. Are you close to the US, get one here.
 

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Home Depot Exide 94R is $129.00.
Great battery.
Walmart Battery is currently made by Exide.
Exide was an original mfg for BMW...
 

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What Speed Limit?
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Yeah the Exides at my local Home Depot have about an inch layer of dust on them lol.

I put a Autocraft AGM from Advance Auto in my M5 last April that was only 2 months old at the time. Not a single issue so far. Was just before Advance switched to Diehard, which are good batteries too.

I mean lets get real here. All batteries are made by 2 companies, so what you chose is not going to be a big issue. The only ones I ever had problems with was Walmarts batteries. They would always crap out after a year or so, hence the nickname "Neverstart" lol.
 

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2001 BMW E39 540i Automatic Sedan, 198 K milesmiles
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I second the "Napa Legend wet cell battery", at any price.
Most important, buy also a battery charge/maintainer if you do not already have one.
 

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Ship Captain of the Ever Given
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Full fielding can absolutely damage an alternator which is why repair instructions want a battery charged to full capacity before starting the vehicle the first time after replacement.
 
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