Normal Current Draw on Parked Car?

[TheGr8Schlotzky]

I plugged my car into a manual charger on friday and unplugged it sunday night. Went to start the car today (tuesday) and it had enough juice to unlock with the fob and turn on my interior lights (LED) and chimes and such, but wouldn't even try to turn the starter, just clicked.

The current draw with the doors closed and alarm not armed is 160 mA, and with the system armed is 170-180mA. What is normal? That doesn't seem high enough to deplete a car battery in less than two days.

[Mogobs30th]

Re: Normal Current Draw on Parked Car?

A battery is going to run on 180 mA for awhile, but Ohm's law is going to dictate that because of the insane amount of amps needed to turn the starter, your battery needs everything it has to turn it. Surprisingly enough, 3800 Series II have a HIGH CCA necessity. It actually does take alot to turn the starters on our cars. If the battery isn't reading ATLEAST 10v using a multimeter, in my experience, the starter will just click.

Its not so much that the 170-180 mA draw is draining the battery completely, its just draining it enough to cause the voltage to drop within the battery. And it doesn't take much.

If your battery is a little old, its probably not holding the charge like it once did, its not getting the charge it once did from the alt., possibly a grounding problem, or something else is drawing off the battery.

Do you know what the draw is off the alarm in itself?

[TheGr8Schlotzky]

Re: Normal Current Draw on Parked Car?

Thanks for the reply, Wes. The battery is about 8 months old and has started the car maybe twenty times. I'm pretty sure it's the alarm that's draining the battery as I sent the brain in for a warranty repair and after about two weeks of sitting with the alarm out, it still gave a good try at starting the car. I'll take it to the installer and get them to fix the draw from the alarm and see if that doesn't fix it. I guess I'll take the battery in to get tested as well.

So you do think that 170mA sounds excessive? That's like the current draw of a couple high power LEDs, isn't it?

[Mogobs30th]

Re: Normal Current Draw on Parked Car?

Amperage is irrelevant, it would be the wattage you want to worry about. If amperage is fixed on the device, wattage and voltage can become a variable in a DC battery system. The only time amperage would be a concern is if you have another device draining the battery.

Now because the amperage is fixed on a device (in most cases), voltage will drop, as will wattage. Lead/acid batteries slowly die off due to the electron flow from the ground (cathode) to the positive post (anode) so eventually the wattage will drop as well on said device. Because voltage drops, so will the wattage.

Im not sure of the draw on a parked car, but do you know the (Ah) on the battery? Might say it on the label....

[ssms5411]

Re: Normal Current Draw on Parked Car?

My car sits with a yellow top in it and after a week its dead , so I'm leaving the charger on it every day now.

[TheGr8Schlotzky]

Re: Normal Current Draw on Parked Car?

Here's the battery:

http://www.autozone.com/autozone/par...ntifier=232746

It says "Reserve Capacity: 95." Would that be amp hours?

[ssms5411]

Re: Normal Current Draw on Parked Car?

I think so, my Optima is suppose to be 200 amp hours reserve. My car sits for long periods of time.

[TheGr8Schlotzky]

Re: Normal Current Draw on Parked Car?

So I checked it out again. It's been sitting on a 1 amp charger for about 21 hours now since it didn't start yesterday and is at 11.6 volts. Unarmed, it pulls 179mAh, and armed it jumps between 180.5-185.0 mAh.

So that's 2.146 Watts peak when armed. A single 194 corner light pulls 3.78 watts and I wouldn't expect it to drain a car battery in two days. Should I have the battery checked out? It's still under free replacement warranty.

[ssms5411]

Re: Normal Current Draw on Parked Car?

Might as well, I had a 3 year old Optima red top go bad but only when driving it hard , my car would shut down with no lights or anything working. Only way I could tell that it was the battery was because it was very hot on the outside of the casing. This was just driving it within 5 min. it would shut down, it has some dead cells in it , which might be your case. Good luck with it.