Re: Dealer Experience (archive)

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: : Took my car to the local Annapolis, MD dealer (March 98 MZ3 and first time for any warranty work other that oil changes) due to the battery being dead each morning requiring a jump start. The dealer could find nothing wrong. I watched the tech work on it. First thing he did was open the hood, which I thought was kinda strange considering the battery is in the truck.

: : A few minutes later the service guy came to me, informing me that they could find nothing wrong. He asked if I kept my Valentine radar detector on overnight, which I never do. I told him that I had checked the battery in the morning with a voltmeter and found it to read 12.0 volts. I thought this was kinda low, should be around 12.6 volts or so. He then went out to the service tech, who connected a voltmeter to the battery (this was the first time the trunk was opened).

: : A few minutes later the service guy came back to me and said they had performed a load check on the battery and monitored the battery drain. Still they could find nothing wrong, and refused to replace the battery because "BMW would not pay for it unless they could find something wrong".

: : At that point I was getting a little upset. I then asked the service guy what a new battery would cost, and he told me about $200 installed. He refused to install the battery without labor charge. I thought that was very expensive for a 10 minute job, as the battery costs $115.

: : The next morning the battery was dead again. I then went to the dealership and got a battery and installed it my self. The car now starts.

: : My question is:
: : Can they tell everything about a batteries condition from under the hood with their gyzmo? They certainly didn't do anything else. They didn't even check the batteries water level.

: 1. Check the charging voltage. Should be about 14 V with engine at 2 or 3 K RPMs this time of year (40 or 50 F temp outside). Then turn on the headlights, radio, seat heaters, etc. It should drop less than 0.5 V. Culprits here are usually the alternator, voltage regulator, or the belt. (Although belts hardly ever loosen these days.)

: 2. Check the cranking voltage. Connect an analog voltmeter directly to the battery terminals. When cold starting, the voltage should not drop below 10 or 11 V. This is sort of a crude load test but it will give you a go/no go.

: 3. Check the battery's electrolyte with a hydrometer. If the specific gravity is too low, the battery is toast.

: 4. Check the power drain with the key off. Loosen the battery's ground connection. Connect a milliammeter to the minus battery post and the ground cable. The milliammeter should read 0, the current is still flowing through the cables. When you lift the ground cable the milliammeter should give a reading. This is kind of tricky, make sure you have your radio codes before you do this, if you cut the power you're going to need them! The reading you get depends on wether you have an alarm etc, but it should be no more than 100 mA at the most. I think mine was 50 mA or so with the BMW alarm. If you get a big current drain you need to start pulling fuses till you find it.

: Seems to me that if you do all the above steps, you should be able to find the culprit. Although with a new battery, and summer coming, I'll bet you have no problems till winter.

I do not have a battery problem but for future reference, if you have to replace the battery, what after market batteries are recommended if any over the OEM.

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