Battery draining with the ignition off

[JimmyUp]

2000 Astro AWD drains the battery while nothing is on. Is this the security system? Is it the FOB circuitry monitoring button press?
While disconnecting the positive battery terminal, sparks can be seen. When the van sits parked for a few months it has to be jump started.
One could assume that while the ignition is off and the door is opened to deactivate accessory power that battery power would not be draining.

[Leeann_93]

The PCM draws some power to keep the settings in its memory, but if it's draining that badly, you have a draw somewhere you shouldn't.

You'll have to use a meter at the fuse box to find out which circuit is drawing when it shouldn't be - and how much.

[stent]

when i first got my van it needed a new battery - the previous owner wasn't using it and it had been sitting for a long time.
i got a new battery and it ran down several times while i took my turn letting the van sit.
my battery drain came from the light inside the console glove box not turning off.

[ptysiek]

Maybe the radio was changed and badly connected after +

[Leeann_93]

my battery drain came from the light inside the console glove box not turning off.

This is the most common cause.

[Mmusicman]

As mentioned... there are several things that have a nominal draw:

* ECM
* Security System
* Key FOB receiver
* Stereo (memory & clock)
(I think that's it.. but there could be more)

All these are nominal.. drawing only minimal milliamps of current.
But a weak battery can certainly be drained even by "normal nominal draw" over a typical period of time.

You can actually test for current draw (with a volt-ohm meter) to see if all is normal.
If memory serves.. you should see less than about .010 amp draw (max.. but I might be off).

Yes.. the glove-box light may not draw enough to kill overnight, but certainly over a few days.
Of course ANYTHING plugged into a cigarette lighter plug can be a draw too.

A slightly faulty alternator can draw some minor current too (bad rectifier/diode) while still working.

The initial spark you see is actually mostly an inrush of current charging capacitors.. but not a steady draw.

If you are not aware... once a good car battery has been drained dead, it loses some of it's storage strength.
Kill a battery a few times, and it will be somewhat permanently weakened.

Even a strong battery will only last so long with nominal current draws.

I always unhook the battery in my 92 knowing it may be parked for weeks, or lately months.
I weakened/killed the previous battery letting it drain dead.. but now I'm running a fresh new one again.
This time recently, it sat for about 6 months.. and then reconnected and started right up.

You can have the battery load tested (which might give a clue)... but this test may not necessarily show the battery's amp/hour storage ability over time.

They make a variety of battery switches.. I'm considering installing one myself.
But for now, I disconnect one battery terminal (when I know it's going to sit a while), exercising care not to over-tighten the battery bolt reconnecting which can strip the battery post.

Cheers...

[tungtide]

I installed a (red) positive disconnect on the negative terminal. My 2002 awd had the same problem. Now problem solved. By installing on negative side no real current passes through the switch. I have the advantage of the van living in the shop so I leave the hood open. Also it’s two seconds to disconnect the negative terminal while affecting repairs.

[Mmusicman]

By installing on negative side no real current passes through the switch..

Not true. For argument sake: what ever flows though the positive side, returns though the negative side.

That negative cable (you have AFTER the switch) feeds high current to the engine block (for the starter and numerous circuits hooked to the block), as well as connects to chassis ground that feeds the rest of the van.

It may however, be possible to separate the current to the starter from all the rest of the 12v system (on the positive side) routed though a switch .. but I believe it may require some wiring mods.

[Devonian]

I had a battery drain which turned out to be:

USB charger left plugged into power point; nothing connected - constant 60mA.
OB2 reader left connected - supposed 10mA after gone to sleep.

Dual relay on trailer wiring for fridge and leisure battery supposed to switch off when engine not running but did not - constant 100mA.

170mA is not much but 2W all the time is enough after a few days.

So, finding the cause is better than clever ways to put up with it.

[AstroWill]

I had a battery drain which turned out to be:

USB charger left plugged into power point; nothing connected - constant 60mA.
OB2 reader left connected - supposed 10mA after gone to sleep.

Dual relay on trailer wiring for fridge and leisure battery supposed to switch off when engine not running but did not - constant 100mA.

170mA is not much but 2W all the time is enough after a few days.

So, finding the cause is better than clever ways to put up with it.

x2, it's usually something common, and once you get a little bit comfortable with a meter it should be easy to find.

[Big_kid]

...A slightly faulty alternator can draw some minor current too (bad rectifier/diode) while still working....

This was my problem, in addition to sitting for long periods. The alternator would charge the battery, but then drain it when not running. A new alternator took care of that.