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Old 09-19-2011, 04:09 AM
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bluebee bluebee is offline
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Location: San Jose, California
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Mein Auto: 02 BMW 525i M54 auto 130K
Pictorial discussion of charging, testing, removing, & replacing the BMW E39 battery

This is intended to be a pictorial thread, showing the steps to remove, test, charge, and replace the BMW E39 battery.

[WARNING] This may be too detailed for some for such a simple task! [ / WARNING ]

Note: For how to actually perform an exhaustive battery test, see detailed procedures here:
- DIY how to test a BMW E39 battery & alternator

For one reason WHY you'd want to test your battery, see details here:
- Warning: I charged my battery today & apparently killed my instrument cluster & MID

Even the MID lost it's clock:

So, today, after Autozone tested the battery, in situ, and found the following:
1. The charging system was good
2. The starting system was good
3. The battery was bad

I decided to remove the battery and charge it OUTSIDE the vehicle (far far far away from the vehicle!) ... and then to test out the procedures listed in the how-to-test-a-battery thread, one by one, in exhaustive detail (for the team).

The first step is to loosen the 10mm nut on the negative battery cable & pull the cable loose; then do the same for the positive cable:

Next step is to remove the 13mm bolt that holds the cross brace to the fender well, and the 13mm bolt that holds it to the floor of the trunk.

Notice I used the brace to short the 'cables' and 'almost' shorted the terminals! That would be a very bad thing!

Then remove the 10mm hold-down clamp bolt from the tail end of the battery.

HINDSIGHT WARNING: At this point, I had completely forgotten about the vent!

So, what I did was try to lift up on the battery handles:

Yeah, right! That thing is HEAVY!

I could not, for the life of me, lift the battery directly upward! So I tilted it to the rear and tried to nudge it up, ever so slowly one end at a time.

Eventually, I had tipped the entire thing on its end!

I don't think this is the proper way to remove it, but, it was the only way I could!

Note: I didn't realize it at the time, but the vent, still attached, must have had something to do with the problems I was having!

Eventually, I muscled the thing out of the vehicle!
Note: Reading "1 Stuck Piece" on the BMW label gave me a laugh!

With the battery out of the vehicle, for the first time, I could 'see' the green hydrometer in cell #2, and I could see there was no date stamp on the negative terminal (after brushing off the oxidation with a wire brush).

Looking below, I happened to notice the washer that was under the hold-down clamp bolt ...

So as not to forget it, I placed the washer back on the hold-down clamp bolt:

And, I replaced the hold-down clamp in its original position (as I lose bolts if I don't put 'em back right away).

I looked for the six cell caps, but didn't see any on the top:

The side view told me the manufacturer was "DBMC, Winston - Salem, North Carolina", which turns out to be Douglas' consumer line, which was (apparently) purchased by East Penn Batteries (details here).

Looking all over, I couldn't find a date stamp. Maybe this engraving is the date, hidden in battery code?
  • DB0412160806

Getting to the hidden caps was as simple as peeling up the sticker ...

Even with a green hydrometer, the battery tested at around 10.5 volts, so I put the battery charger on. Guess what. It pegged (again) at something higher than 6 amps.

Yet, the DC voltage was only 11.40 volts, with the charger running (I expected higher).

Suddenly I had the bright idea of checking amperage (maybe the gauge was wrong on the 25-year old charger) ... so I pulled out my Radio Shack ammeter ...

But, I soon realized that ammeter probe was only for AC current, so, after about a half hour, the amperage on the charger meter lowered somewhat and I felt I could risk the Fluke 75 on the 10amp setting.

By now, the charger was reading about 6 amps, which jived with the Fluke DC amperage reading.

At some point, the VOLTAGE on the fluke wouldn't read; it just showed as overloaded. I wasn't sure what that meant (and I didn't snap a picture because I didn't believe the reading)... but ... maybe ... just maybe ... the charger has an intermittent high-voltage spike???

Anyway ... this picture shows why a sharp awl was a 'bad idea'. Do not use a sharp awl to twist the caps out!

For one, the caps don't twist out. For another, you'll puncture the super-thin plastic of the head of the cap, and, well, I'm sure that would allow electrolyte to evaporate out in the wrong way.

Giving up on spinning the caps out (they don't spin out), and on the sharp awl (I punctured the cap head), I used an 1/8th inch screwdriver. I really needed something thinner, but that was all I had.

No matter how careful I tried to be, the cap chipped at the edges.

With all six caps off, I checked the fluid levels and noticed some were below the plastic L-shaped level indicators:

So I got the bright idea of using a 1ml eyedropper to fill but after fifteen of those, I gave up and moved on to a 10ml graduated cylinder to measure how much water was being poured in.

The amount of fluid added was:
  • Cell #1 = 15ml
  • Cell #2 = 15ml
  • Cell #3 = 15ml
  • Cell #4 = 60ml
  • Cell #5 = 20ml
  • Cell #6 = 30ml
I wonder if tipping the battery on one end had anything to do with the top end needing more water than the bottom?
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Last edited by bluebee; 09-19-2011 at 11:02 PM.
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