Hello everyone. I have a '90 420SEL that has been a second car for a few years, so that means it doesn't get driven much.

I do use a Battery Tender(r) a few times a month to top off the newish MB battery, that I have load tested with an old Snap-On AVR machine. The battery checkes out ok and the alternator seems to output around 45amps or so.

Here are the other symptoms:

I have a high amount of ripple showing when under a high amp load.

The battery goes dead after a few days. When I bought the car it had been jumpstarted/quickcharged many times by the slimeball who owned it. Mostly becaue the battery had a bad cell.

Being "frugal", I replaced just the OVP relay that was bruned out, the battery, and the voltage regulator right after buying it.

In hindisght the alternator probably has a bad diode and is discharging the battery, and I'm probably answering my own question.

I just bought the Snap On machine and couldn't help playimg with it, it's just like the one most shops used in the mid to late '80s. When I used to be a shop rat, I would drool over them.

Anyways, anyone have any thoughts? Am I being too much of a nerd? Should I just find a good alternator and stfu?

Thanks.