Normal battery drain

[Scott R]

What would be considered "normal battery drain?" I let my 1980 SC sit for a week or so at a time between starts and I'm getting the red charging light on for a few minuets after starting. I charged the battery overnight (six month old battery) and the light was not after I started it.

Anyone have any insight into this? Do I have the early indications of charging problem? Or is this normal battery drain? I searched the archives and I found nothing that exactly fits my scenario.

[Wil Ferch]

Sorry that no one posted yet......

First, what is your standby battery voltage? Should be 12.6 volts or so for a full charge. The "slope" of the curve is pretty steep. A 12.4V battery is about 75% of full charge. 12V or high 11's mean "dead"...essentially.

For my 85 Carrera...the standby amp draw ( clock, etc) is 16 milli-amps ( 16 mA ) . Our "big" batteries have , I think, an 88 amp-hour rating. This would deplete a battery in 88 hours if the draw was 1 amp. 16 mA ( let's say 20 mA for math convenience) would drain this in about 500 X more time....so 500 x 88 hours = 44,000 hrs...about 2000 days or about 5-6 years !

( I hope this math is right !!!! )

..I would check the battery condition as well as the standby milli-amp draw. The electric gadget happy 964's upped the standby draw to 64 mA...for comparison.

-Wil

[javadog]

Scott,

The red light should go out right after you start the car, especially if you rev it a few hundred rpm after it has settled down to a smooth idle. I'd suggest having the draw on the battery measured and the charging system tested. A week between starts shouldn't be a problem if everything is healthy.

Even though the battery is pretty new, it can still have problems. A few of them do fail and this is more likely if the battery voltage has been allowed to drop for any length of time.

JR

[Scott R]

I drove it to lunch today (I work out of my house so I rarely drive anywhere) and the red light was dimm, and stayed on for about three miles. I do however have great starts, and lots of cranking power to my new high torque starter. I guess I should probaly pull the alternator and have it bench tested based on what you said about the amount of time I let it sit.

[Kmatts]

hang on a second Scott....a 50ma drain is considered tolerable for your car. (if you are running some crazy stereo or alarm system, please reconsider your battery life). If you are not able to test your battery and charging system, please FIRST pull your battery out and take it to your local shop and have it tested. Pulling the alternator is not neccessary quite yet. just because your battery is only 6 months old, does not mean its good! It could have a shorted cell or it could be sulfated from sitting with a low charge too long in the warehouse.
(this happened to me, fyi).
hope this helps.
Kyle

[Scott R]

Thaks, I will get the battery checked this week. It does have a mondo sound system installed by the PO, there are apms and speakers everywhere. I have checked that they are all shut down when the car is off and they are, so I suspect the battery then. I have an OEM radio waiting to go back in, however when I took it to the stereo shop I did not have these special little plugs that the radio requires to be installed. Once I find the Blau plugs all of this junk is coming out.

[wholberg]

The stereo system sounds like a likely culprit. Some PO installed an aftermarket amp in my car that was constantly draining the battery until I installed a relay to shut off power to the amp unless the ignition was powered. Try pulling the fuse for the amp (if you have one) and see if the drain decreases.

Of course, in an old car, there are always other possible sources of power drain.

[Scott R]

Originally posted by wholberg
The stereo system sounds like a likely culprit. Some PO installed an aftermarket amp in my car that was constantly draining the battery until I installed a relay to shut off power to the amp unless the ignition was powered. Try pulling the fuse for the amp (if you have one) and see if the drain decreases.

Of course, in an old car, there are always other possible sources of power drain.

I'll do that, it actually has a total of four amps, two under the drivers seat, and two up front. I think I may pull the entire system out, or drop it off and have it all removed. I don't really use it anyway.

[Wil Ferch]

Basic question then....did you actually *do* a standby amp-draw check?

That is...what makes you think the amps are "off". I would only trust an amp-draw check via a multi-meter.... and not that "it's switched off".... let's be clear.

- Wil

[wholberg]

Scott, to second Wil, the power light on my amp would go off when the car was turned off, but a meter showed a steady power drain, regardless.

FOUR amps? Holy cow! Could the PO still hear anything at all, or did you just talk to him really loud???

[Scott R]

Originally posted by wholberg
Scott, to second Wil, the power light on my amp would go off when the car was turned off, but a meter showed a steady power drain, regardless.

FOUR amps? Holy cow! Could the PO still hear anything at all, or did you just talk to him really loud???

When I purchased the car (not running) the PO was trying to sell the car based on the stereo system. Now imagine this scene... Me with check in hand and a car dolly with me, the PO has me sit in the car and he turns the radio on, he cranks this country music so loud I swear peoples ears were bleeding in the next county.

In his mind the $1200 he charged me for the car was for the radio alone. I don't know how he got his hands on this car, but he had no clue about it. He had been told by a Meinekie muffler shop that the engine was shot because it blew clouds of smoke while running. (Oil level was 2 or 3 quarts to high) I happened to notice this when I was checking the thing over prior to purchase.

So rather than let on what we had found out, I brought the car dolly and told him I was probably going to part it out. It has still taken me a ton of money to get it sorted back out, including replacing every oil seal in the car, rotten tires, and everything on the CIS system, new tensioners, valve adjustment, door checks. It was just basically neglected, however not entirely lost, a leak down shows only 2 to 3% so I'm hoping to have it for a while.

This was the evening I brought it home:



Notice the PO's "Harley Davidson" sticker, there were others stickers inside as well, and a "Harley" front license plate.



Here it is today, leak free and running



Needs to be lowered, that's on my list after I get the last two oil lines replaced.

[wholberg]

It looks very nice. Even though you had to put a lot of work into it, now you know exactly what you have!

[Scott R]

Originally posted by wholberg
It looks very nice. Even though you had to put a lot of work into it, now you know exactly what you have!

Thanks, I still have a way to go yet, I need to replace the dash and recover the front seats and then tear it down and paint it. I have all the supplies to do the work, just been short on time lately.