Forgot to run the car

(The later the model year, the more gadgetry now (burglar alarms from factory or 'listening for a key-clicker' to unlock, etc.) Got a non-toy volt-amps-resistance meter? 'VOM' that is.

Simple test re all the 'smart'-gadgetry added:
just disconnect (either battery cable) and put an ammeter in series. Ohm's Law tells you whether the nominal drain is *normal or unreasonably high; pinning that down is the tedious task of disconnecting things, as can turn into a nasty Bug-hunt.) A sick transistor or a capacitor can account for many of these drains.

* Under 30, 40 mA (milliamps) is upper limit for normal. You can do the arithmetic -vs- battery amp-hour rating; it's just algebra E=IR right? At "a tenth of an amp" say, you can see that it's not many days before No-go.

(Cable back on terminal) Couldn't hurt to note voltage at low up to medium RPM, thus eliminate alternator or its regulator not recharging well.. Lots of batteries are replaced via guessing rather than a few minutes sleuthing.
Over here that can kill most of a C-Note.

Luck

Post #417,511 by drook 3/24/17 6:13:28 PM 3/24/17 6:13:28 PM Reply	Forgot to run the car I haven't driven since before shoulder surgery on 1/31. I just went to get something out of my car and the battery is deader than a doornail. Balls. -- Drew
Post #417,515 by a6l6e6x 3/24/17 10:52:45 PM 3/24/17 10:52:45 PM Reply	So, what's discharging it? Parasitic loads like a clock shouldn't be enough. Alex "There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge." -- Isaac Asimov
Post #417,523 by drook 3/25/17 10:12:32 AM 3/25/17 10:12:32 AM Reply	Probably the bluetooth radio receiver I've got one of these that I forgot to unplug. -- Drew
Post #417,517 by crazy 3/25/17 4:34:28 AM 3/25/17 4:34:28 AM Reply	Does a jump "take"?
Post #417,518 by static 3/25/17 5:12:55 AM 3/25/17 5:12:55 AM Reply	New battery needed, methinks. Although car batteries do self-discharge, it's not at the rate! Wade.
Post #417,520 by pwhysall 3/25/17 8:15:59 AM 3/25/17 8:15:59 AM Reply	Re: Forgot to run the car Concur with the above. I left my old BMW 5er for a couple or three months without driving it, and it started on the first turn of the key.
Post #417,522 by Ashton 3/25/17 8:56:46 AM 3/25/17 8:56:46 AM Reply	A few numbers might save a C-note (The later the model year, the more gadgetry now (burglar alarms from factory or 'listening for a key-clicker' to unlock, etc.) Got a non-toy volt-amps-resistance meter? 'VOM' that is. Simple test re all the 'smart'-gadgetry added: just disconnect (either battery cable) and put an ammeter in series. Ohm's Law tells you whether the nominal drain is normal or unreasonably high; pinning that down is the tedious task of disconnecting things, as can turn into a nasty Bug-hunt.) A sick transistor or a capacitor can account for many of these drains. Under 30, 40 mA (milliamps) is upper limit for normal. You can do the arithmetic -vs- battery amp-hour rating; it's just algebra E=IR right? At "a tenth of an amp" say, you can see that it's not many days before No-go. (Cable back on terminal) Couldn't hurt to note voltage at low up to medium RPM, thus eliminate alternator or its regulator not recharging well.. Lots of batteries are replaced via guessing rather than a few minutes sleuthing. Over here that can kill most of a C-Note. Luck
Post #418,312 by drook 5/23/17 9:34:41 PM 5/23/17 9:34:41 PM Reply	Took a charge, all good now ... And now I own a charger -- Drew
Post #418,314 by pwhysall 5/23/17 11:59:14 PM 5/23/17 11:59:14 PM Reply	Your local garage should have a doodad that... ...measures the health of your battery.

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