battery drain

[30 a truck]

I have a battery drain. New AAW harness, new everything electrical. When I install a test light in the positive cable, it flashes then goes out. Any idea why it only flashes?

[VetteVet]

Could be draining through a solid state device with a transistor or capacitor that turns off when the light power is applied. Just a guess. Try it on the negative cable.
Is the light bright or dim? You could get better readings with a multi meter set on 10 amps.

[30 a truck]

Light is not as bright as 12 volts. Would a Retro radio have a solid state device in it? Only thing that I can think of that would have anything in it. I will check the negative side today after work.

[BugzC10]

How fast does it drain? Reason I asked...I installed Vintage Air. If I didn't start it for a couple weeks, my battery didn't have enough power to crank it over. I called Vintage Air, as soon as they said the system has an EMC, it dawned on me that, that was the source of my drain. I didn't want to keep in a trickle charger. Since then I've changed to a Optima battery without any drainage problems, however I usually still start it at least once a week.

[30 a truck]

7-10 days

[demian5]

Leave test light on negative side and start unplugging stuff till it goes out. Make sure your dome light isn't on with the door open

[30 a truck]

That is the problem, light goes out in 1 second.

[demian5]

Originally Posted by 30 a truck

That is the problem, light goes out in 1 second.

A one second load a battery drain does not make...

Leave test light on negative side and start unplugging stuff till the light no longer comes on for one second then goes out.

[30 a truck]

It comes on for 1 second, then does not come back on until it is unconnected & reconnected.

[demian5]

Originally Posted by 30 a truck

It comes on for 1 second, then does not come back on until it is unconnected & reconnected.

Then you don't have a drain. Get your battery tested.

If battery is good, I refer to my previous replies.

[30 a truck]

Battery is good. Been checked by 2 different places.

i do have a drain. thank you for your comments.

[davepl]

The retro radio might have a memory or other capacitive storage device that takes a second to charge.

But if the light goes out, no current is then flowing, so why do you think you have a drain? Any drain not enough to keep a test lamp lit is not a drain.

I'd hook your ammeter inline with the negative cable and see what's actually happening, if you're reasonably confident that the drain is within your meter's capacity (10A or whatever).

[ubtripn]

That's how I do it, tap the negative cable on the post , if there is an arc I start removing fuses one at a time to identify the draw.

[30 a truck]

OK, IF I don't have a drain, WHY DOES A BRAND NEW CHECKED TWO TIME BATTERY DIE IN 8-10 DAYS???

[demian5]

Originally Posted by 30 a truck

OK, IF I don't have a drain, WHY DOES A BRAND NEW CHECKED TWO TIME BATTERY DIE IN 8-10 DAYS???

You need to figure out whats turning that light on for 1 second.

[30 a truck]

No comment!!!!!!

[BugzC10]

What type of aftermarket electric / electronic devices do you have on your truck...i.e. Aftermarket AC, Radio, ignition etc. Or is it all stock?

[30 a truck]

Be Cool air & Retro radio. Nothing else. Crate motor with HEI. Stock gauges.

[donandal]

My retrosound had two positive connections. One powered the
typical radio functions and was powered thru key-on ignition.

The other powered the clock and memory functions, and was
powered thru a fused continuous battery source, so that would
be a potential slight draw.

[dmjlambert]

Multimeters have a DC amps function. Wire one into the circuit between the negative post of the battery and the negative battery terminal. You can wrap several turns of bare wire around the battery post, twist the ends, and use an alligator clip to connect to the negative multimeter lead. Set the multimeter to 10A DC range first. Connect the positive multimeter lead to the disconnected battery terminal. The current the truck draws will all go through the multimeter. You can run stuff that draws up to 10A, so don't turn on fans, horn, headlights, high power radio, starter motor, or stuff like that while using the multimeter.

Use the 10A function first, and plug the positive test lead into the 10A socket on the multimeter. If you switch the key to the on position and have the radio and other accessories off, you may find a couple of amps of draw from things like the distributor. Parking lights will draw another couple of amps. If you measure less than 0.25A with everything off, then you can plug the positive test lead into the volt/ohm/mA socket on the multimeter and switch the range to 250mA. Or you can just leave it connected in 10A mode. 0.1A = 100mA. If you read more than a couple dozen mA with everything off (and the key off), start unplugging fuses until you find the culprit.