86 Camry radio killing battery

[woodduck]

Thru a process of elimination I have decided that the aftermarket radio I put in is killing the battery. The original unit didn't have clock memory--the new one does. I have pulled the new radio out and the voltage has stopped dropping. I am talking about just a 1/2 volt drop from monday till today, but this car isn't driven daily and thats enough to kill it after a few days. Any suggestions?

[toyomoho]

Later model Camry have a clock and radio setting memory without battery problems. This thing have a remote amp? Connect the radio and temporarily install an amp meter between the battery and battery cable. See how much current is being drawn.

Might be your battery is dieing or you charging system is not bringing it up to full charge.

[timebuilder]

Here is your test.

Connect a meter capable of milliamp measurement between the positive battery terminal and the positive battery cable. The standard for key-off, doors closed, courtesy lights off battery drain is from 10 to 50 milliamps, or 0.010 A to 0.050 A DC. I would expect a Cadillac to be up around 40 milliamps, and I would expect no more than 20 milliamps for your car, more likely between 10 and 15 milliamps. If this "parasitic drain" figure is correct for your car, then your battery is likely the problem, and not the clock.

[woodduck]

This is a new battery and shows 14.5v when running. No amp or anything else. I will get my good voltmeter back from my son and check the current draw. My clamp-around amp meter isn't sensitive enough to show anything.

[timebuilder]

Good.

Remember, everything is off, key out, doors closed for this test. You are replicating how the car is configured when parked overnight.

Just an FYI:

Some modern cars have circuits on time delays so you have to wait a minute or two before the reading settles. Some of the younger techs would get really excited with some cars, exclaiming that the car was "pulling almost an amp!" I'd rush over and pretend to be amazed...

[woodduck]

When I first put the meter in-line it reads 42ma then quickly settles to 17ma. Does this seem normal to you?

[Blackhawk3D]

Neither are above the 10-50ma range he gave, so I'd say it's okay. Remember that when the car is running there is juice from the alternator going to the battery posts, so the voltage will be higher.

[timebuilder]

Originally Posted by woodduck

When I first put the meter in-line it reads 42ma then quickly settles to 17ma. Does this seem normal to you?

Yes.

It's possible that you have an intermittent draw, such as can happen when a door is not completely closed, and an interior light remains on. Right now, things are good.

You might want to have a conductance test on the battery to check its condition.

[marc780]

If its too late to return this radio, (sounds like its drawing way too much power when its off!) rewire the hot lead. You can use what is called a fuse tap, and just tap into something on the fuse box that only gets power when the ignition is on. Then the radio will not draw power
while the car is just sitting.
Or an even easier way, but more of a pain long-run, wire in a toggle switch and remember to shut it off when you leave the car.

[timebuilder]

Originally Posted by woodduck

When I first put the meter in-line it reads 42ma then quickly settles to 17ma. Does this seem normal to you?

Yes. If the value quickly settles down to 17 mA, that's a good figure. If that draw is too much for your battery, then you need a battery test and charging system check. For example, you can't charge a battery with AC, and a bad diode can put AC across your battery.