This is Susan's new old 850. There was a problem with the glove compartment light so the PO
just took out the fuse. Still after 4 days of not driving the battery is down.
Every other day is OK. I went over all the other fuses with my fuse with a small light
bulb across it and ONLY found an apparent leakage in the circuit for the glove box,
and the fuse is out of that circuit so it should not be a problem.
Battery is new. Any unfused circuits on these? Where else should I look?
First chance I get I'll test charging voltage and leakage across the battery cable
but have not had the opportunity yet.
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George Downs Bartlesville, Oklahoma

No circuits are unfused. Check the alternator output first, it should be around 14-14.5V

You might also want to check the trunk light, just pull down the center armrest and look through the pass through for a light.

Use a penny or a felt chair leg sticker to trip the glovebox door light.
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My name is Klaus and I am a V ♂ lv ♂ holic

Both the glovebox door light and the fuse that serves its circuit have been removed
so there should NOT be any leakage from it or other interior lights. Also the door latch.
I plan to try to fix up some kinda latch for it but probably will not replace the light.
If the trunk light is on the interior lights circuit, that is the fuse that we have removed.
But I will check it, also alternator voltage.
Many thanks.
Even the headlights are fused on this car? On most cars they are not.
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George Downs Bartlesville, Oklahoma

"Even the headlights are fused on this car? On most cars they are not."

Are you sure about this ???

I just pulled-up the wiring diagrams for a half-dozen cars produced in the last 15 years and did not find one that did not have it's headlights fused.

Can you give some examples?

How about the Volvo 122, 1800, 164, etc etc.?
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George Downs Bartlesville, Oklahoma

OK. I think you made my point for me.

Those are the cars I usually work on. The 850 may be out of my depth.
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George Downs Bartlesville, Oklahoma

I'm close to being an electronic illiterate, but isn't there a way to measure how much amperage is flowing through battery drainage when the car is at rest?

There is, but current-measuring meters are easily damaged because the whole current
flows through them. You can put an ordinary ammeter in series with the battery cable
but if you hit the starter while it is there you'll burn it up.
The beauty of the light bulb tester is that it is sensitive to fairly small current levels
but is not overpowered by the full 12 volts because of its inherent resistance.
An ammeter has little or no resistance.
If you can verify (like with the light bulb tester) that the current flow is small,
you can then more or less safely put an ammeter or multitester set for current in the circuit.
I have not done this yet, considering the time involved. It was pretty quick to check
all the fuse sockets with the light bulb tester. More time consuming to actually
measure small currents (if any).

Voltmeters are high-resistance devices and do not ever get much current.
Ammeters are essentially zero-resistance devices because you have to conduct
all the current to measure it.
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George Downs Bartlesville, Oklahoma

Thanks. You just doubled my knowledge of testing for amperage.

"...current-measuring meters are easily damaged because the whole current
flows through them..."

OK, so if the only method to measure the (possibly damaging) amperage level is by putting the meter in series with the battery cable, could you then put something like a rheostat in the loop and bring it up slowly, stopping short of the meter's limit?

Sorry, I know we're getting a bit off subject. I'm just trying to gain some smarts.

You probably could. Many meters have multiple ranges that do more or less the same thing.
You just have to be sure that the FIRST one is big enough to handle the current.
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George Downs Bartlesville, Oklahoma