90 Camry Slow Battery Drain

My 1990 Toyota Camrey LE with just 70,000 miles on it and in excellent condition won't start when not driven for 7 to 10 days. Battery and altenator check o.k. Toyota mechanics have not been able to pinpoint the cause. They told me to leave the car with them but cannot guarantee that they will find what is wrong and, if they do, cannot guarantee they can fix the problem. Will somebody please help me!

Reply to
Pete728
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As I'm sure the mechanics told you, you likely have a stray path to ground from the battery; you can check this by putting an ammeter in series with the positive terminal of the battery with the ignition off. If it reads more than a few tens of milliamps (as I suspect it will) you need to find the stray ground path.

Alternatively, you can put a switch capable of handling the starting current in series with the positive terminal of the battery. Turn the switch off whenever you want to leave it parked for more than a few days.

Reply to
Nobody Important

If you find increased battery drain, you are lucky and are on the road to finding the cause.

Sometimes, however, the drain is intermittent and these can drive you NUTS.

I had this on a previous Buick Regal, and the battery would go down every night (new battery, etc) unless I disconnected the battery. I finally found it. It was a seatbelt retractor that was energizing at night, time after time.

I presently have a Buick Reatta that is behaving similarly. When I put the ammeter in series with the battery, I get an initial high current reading (which is normal) until all the systems go into hibernation. Takes a minute or two. Then, the drain drops to 30-40 milliamperes. BUT, in a few days, the new battery goes flat. I am sure it is another intermittent, and am getting geared up to hunt for this one.

In order not to ruin the new battery, I will set up a 12 volt filtered DC power supply in place of the battery. Then I am going to try to borrow a strip chart recorder (or maybe interface the measurements to a computer) to monitor the current drain day and night. If I can catch it misbehaving, I will start removing circuits or fuses one by one until I track the devil back to its lair.

Reply to
<HLS

== Find someone who specializes in auto electric. Tracking parasitic current drain may not be obvious, but there is a definite procedure to follow to isolate the circuit and then track down that circuit. But first, make sure the headlights were turned off at the switch. If the headlights are on, you turn off the ignition and open the door, the headlights go out, but there is a relay that will cause the battery to run down over time. Do the dome light, glove box light and trunk light all work correctly? Faults in those circuits can cause the probelm you're describing. Each one need to come on when door opens and off when door closes.

Reply to
Daniel

This is very true. The problem comes when you have intermittents.

A mechanic can guess what the intermittent might be, and try the 'tree' approach, but this can take a long time. Time=$$

If you have increased residual drain at all times, it is much easier to find.

Reply to
<HLS

Reply to
BigJim

The maths goes like this: A good condition battery can supply about 50 amps in one hour. Now if your car electrical system is bleeding away 100m ah, that's 0.1A hour which will totally (more or less) discharge the battery in

500 hours. Now most batteries will fail to activate the starter well before totally flat, so go for 2/3 flat. This reduces the time of useful battery-life by a third or down to 330hrs. This is still a long time,..so the drain should be up over an Amp, to stuff the battery over night. Then consider what one interior light consumes, around 10 to 18 watts (Festoon bulb)e. Power in watts = volts multiplied by current,..so the little light draws well over an Amp.

If you want to rule out your car's electrical system, one easy way is to disconnect the earth or negative battery connection over night,..then re-connect in morning.

Jason

Reply to
Jason James

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