If you leave your car off for 2 days (a weekend) without driving it, what's the average voltage of your battery after 2 days?

I also assume that your car has an alarm system and/or clock that consumes between 50 mA to 200 mA.

Thanks.

Eric

Never really did this myself but all things considered would question if not 12.2-12.5 volts. If not im that range might question my findings a little.

Be a little careful here. You are looking for data between 11.9 volts and 12.4 volts. The typical analog meter will not be accurate enough for this purpose.
Without a very good digital meter, the data isn't going to be valid.

I should add that it's not an issue with a good battery. I can start the SD after sitting for 60 days without a problem.

A good battery will show the same voltage for weeks, even in a car that is using a few mA for accessories.

That said, I'll do an actual test, but I'll need to find a few days when my car won't be driven! If we get some nice weather I'll be able to do that.

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

I've tested mine before, it was 12.56 when I parked it, and it was still at 12.56 about 3 days later, so no change at all essentially, its a 2 month old DieHard International. My old MB battery called it quits after several winter days of long-cranking, at its end it was only giving about 7-10 seconds of good cranking before it would slow way down.

__________________
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'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I've tested mine before, it was 12.56 when I parked it, and it was still at 12.56 about 3 days later, so no change at all essentially, its a 2 month old DieHard International. My old MB battery called it quits after several winter days of long-cranking, at its end it was only giving about 7-10 seconds of good cranking before it would slow way down. The new one I've cranked as long as 15-20+ seconds on a real cold day, it cranks a bit faster with the DieHard, so it also helps start it faster.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Doing this would be an inconclusive test. If you are having problems check the voltage across the battery with engine running and reved up a little. It should be within about 13.5 and 14.5 volts if the alternator is working. If it isn't check the brush pack, if it is, have the battery load tested. If both of these things are okay, do a voltage drop test on the starter circuit.

Good luck,

Something no one has mentioned, is this a so. Cal. car or nothern Maine in the winter. Batteries do not like cold and don't bounce back from discharges as easily. Just a thought
Rich

__________________
88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
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