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Wednesday, December 6, 2023

Doug's Domain

Doug Vetter, ATP/CFI

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Tuesday, October 5, 2010

Battery Failure

And so it begins. With a bit over 8000 miles on the odometer the E46 experienced its first maintenance issue.

Last Sunday, just after I finished washing the E36, I decided to take the E46 out for lunch. I disconnected the battery tender, hopped in and turned the key. I waited a few seconds after turning the key to position two just to give the systems and pressures time to stabilize. While in this position the gauge cluster came alive as expected, the second I turned the key to the start position I heard a click from under the hood and the entire vehicle went "cold and dark".

(Image: First E46 Battery Failure)I'd seen this movie before, so I immediately got out of the vehicle and popped the trunk to take a look at the battery. The first thing I noticed were the faintly glowing trunk lights. This and the fact that the battery was almost five years old gave me all the information I needed to diagnose the problem as a failed battery. So, instead of reaching for a VOM, I reached for my ratchet set to remove the battery.

Pulling the cover off of the battery proved to be more annoying than in the E36. The trick is to remove the two plastic screw fasteners holding the inner portion of the cover down, pivot the inner portion upward sufficiently to get a hand under the center portion of the cover facing the exterior of the vehicle. Then a good push straight upward will release the cover from a tab formed into the body. There is no reason to move the trunk liner though I admit I was tempted to do so after a few frustrating moments trying to figure out what was holding the cover to the body.

WIth the cover removed I used a 13mm socket to remove the two bolts holding the battery clamp to the vehicle, and then used a 10 mm socket to remove the positive terminal followed by the negative. Upon removal I noticed that the battery indicator was clear, meaning that no electrolyte was touching it. I shook the battery a bit and saw a green indication appear briefly. This told me that the electrolyte was present but too low for normal operation. I'm not sure if that's what caused the failure, but it did give me pause as to whether it resulted from constant charging by a battery tender. After all, contrary to popular belief, these batteries are not sealed and will off-gas as required during charging. Still, four and a half years is an acceptable (or at least typical) lifespan for this type of battery, so I'm not exactly complaining. I have no plans to discontinue using a battery tender, if that means anything to you.

Given that it was Sunday and the dealer was closed, I simply stuck the old battery in the E36 and figured I'd trade it in first thing Monday morning. I arrived at the dealer that morning to discover the old dealership building being demolished to make way for a new BMW center (yes, that same $15M building the prior owners refused to build). I knew the new owners were planning to do this for some time but I have to admit it was kind of odd to arrive on the property to find the building at which I'd bought two BMWs gone. I had to walk around a bit before I found the parts department in a temporary location, but soon spotted familiar faces. Unfortunately, as it turned out, the battery was not in stock but they promised to put it on order and give me 20% off on delivery.

Today I picked up the battery (a new part number of 61-21-7-586-961) and installed it with little fanfare. As soon as the negative terminal touched the battery the trunk lit up brightly. That and a quick check of the gauge cluster with the key in position two confirmed I'd fixed the problem.

The battery retailed for $196 (!) and I walked out the door with a bill for $153 with tax. Because of the chaos I didn't think to ask one of the service advisors what the dealer now gets for a battery change but some searching revealed a total price in the neighborhood of $350-400, depending on the vehicle. Considering that most dealers charge a diagnostic fee of between $80 and $100 for any electrical faults along with 0.5 hours labor to install the unit, that doesn't seem too far off...hence the $185 in the labor saved column.

Mileage: 8100, Parts: $153, Labor Saved: $185