Battery voltage with engine off / on? 95 E320
 

For several years we have experienced some type of a minor battery drain: don't drive the car for a few days, maybe a week, and it needs a jump to get going. However, since we usually drive it every day it always starts even on zero-degree days. The car has the original Bosch 90A alternator but we have gone through 2 Interstate batteries in four years.

The car has sat for the last year due to needing repairs and us having other cars available to drive. I have tried to start the car every couple of weeks and drive it up and down the street a couple of times to keep everything free. However, since it sat virtually the whole year, a fully charged battery would only start the car for about three days, before it would go so flat it wouldn't even have the power to run the radio anti-theft LED. Recently we changed the headgasket to fix the oil leak and installed new suspension accumulators to fix the bouncy ride. We are going to run it daily again starting in December. Something has changed though...the battery after a full charge will not start the car without help from a jump-pack, but it will run the headlights, interior lights, tailgate closing assists, etc...for weeks without running. So I think the battery junked out (again) but the drain has disappeared (due to moving the wiring harness around?).

So I replaced the battery with a new Mercedes-Benz battery. It is much larger than the Interstate batteries, needing every millimeter of the battery box just to fit in. However, the Interstate batteries weren't too small as they were matched out of the catalog to our car model. And the new battery was ordered by the dealer after matching it to our VIN. So what gives? The new battery was about $158 and seems to be the nicest battery I have ever seen. I don't want to wreck it with a little electrical drain so I'm trying to find out what the average E320 has for a sitting battery voltage with engine off, and to verify the alternator is working what is the charging voltage with all accessories off?

I think the drain has disappeared but want to be sure...this battery starts the car quicker than it has ever started before. Any '94-'95 E320 owners to help me out here?

Thanks

Just my $0.02

Does this car have a replaced wiring harness?

It would seem to me that an intermittent short may discharge a battery, but, unless you have fixed the problem, it very well may just come back when the wiring moves again - at which point, you'll be deep-cycling the battery again. It certainly sounds like the easy starting right now is a byproduct of having a brand new, fresh battery.

My battery is at 12.49V when off, and 14.10V at idle.

If you have a small current leak, you might not see it directly at the battery in terms of voltage. Perhaps closer inspection of the fuses may help you isolate where it might be. OTOH, maybe your leak is large enough to be more obvious.

if u have a drain, u can use an led test light, disconnect the postive wire, and put the test light on the negative, if theres a draw the light will illuminate, if it does, pull fuses until it goes out, theres your draw.....