Within the last 90 days I replaced the battery in my 1990 300 SL. I did it mostly as a precaution since the battery was over 5 years old . Now the battery is going dead after sitting for a few days. If I put it on a trickle charger it will start ok for the next couple of days. I had the car tested and the report was that the charging system was operating properly and there wasn't an unusual current draw. The new battery is an Interstate. Could that be the problem, or what should I be looking at?

Bob

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BobH 90 R129

My guess is the shop checked the circuits controlled thru the primary fuse box. They likely pulled each fuse, then connected a ammeter to look for current draw.

You may be dealing with something "aftermarket" in nature such as an alarm system, or sound system.

Interstate batteries are OK, but it's entirely possible the battery is flawed. Did they load test it?

Mike, I don't know if they did a load test. I was relying on the shop to have some expertise in an area where I have none. I may have overestimated their capabilities.
Bob

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BobH 90 R129

I would try an optimat battery personally.

but definately want to check your car for any electricity drains.

The first thing I would do is hook up a volt meter to the battery and let it sit for a few hours, then check the voltage again and see if it is lower than when initially hooked up.

The next thing would be to test the battery the same way but not hooked up to anything.

It could be the incorrect interstate battery was used, but that shouldn;t make too much difference.

Personally I am a big fan of optima batteries. I've had mine for 4 years now, and never had a problem with it.

I use the blue top deep cycle marine one, but the red top reversepost is what I have put into many cars.

I have put the red top reverse post in porsches, ferraris, vw's, benzes, bmws, etc, and never had a problem with any of them.

I like interstae batteries. I think they have one that is a nice euro replacement, I think it is the mtp91, which is the smae size as most bmw and benz batteries.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

You mentioned that you replaced the battery as a precautionary; did you have the problem with the old battery?

If you did not have the problem, you may have a bum new battery on your hands.

I'm curious as to how one can use a deep cycle battery successfully in an automobile?

Do these deep cycle batteries actually last longer in cars than std. auto batteries?

It would seem that if this were the case, everyone would be doing it?