Parasitic Battery Drain

[harrylime]

Brought back my Battery from Lexus this morning, assured that it is fine. I have ordered a starter contact set because the consensus is that this is the likely culprit. I would like to also eliminate parasitic Battery drain and a faulty alternator, so found this bloke on YouTube explaining how to do these.

I have done the parasitic drain test as described and seem to be getting a draw on the Battery, with everything off, and key out, of 4.7 amps, so it is possible that the starter is not the only issue.

Having fully charged the starter, I tried the car and it would not start. The starter turned for a couple of seconds before packing up. The next time I tried it, it started.Totally befuddled now, any ideas anyone?

[Mybikes a cx500]

4.7 amps! that's easily about 10 times what it should be, sorry to ask, but you are reading the meter correctly? 0.47 amps, ie 470 ma. would be nearer the correct reading. For 4.7Amps, I'd suspect the alternator diodes failing.

The starter issue is quite possibly entirely separate, just the contacts failing, entirely consistent with your symptoms. But it does mean taking the inlet manifold off to get at the starter, not a small job.

[harrylime]

I'm a real amateur and don't really know what I'm doing. The meter is set on the 10 amp setting and is reading 4.7, so I assume 4.7 amps, between the negative terminal and the negative cable

[harrylime]

what really puzzles me is what can take nearly 5 amps when everything is off?

[Bluesman]

I have heard that it is the security system that is constantly using power, I dont know how. Mike

[plexus914]

Before you measure any rest current your car has to get into "sleep mode". Keep in mind that in order for the car to sleep at all, it must be off
and nothing can be "touched" (no opening of the trunk or doors, no pressing any buttons on the key fob, etc.) If something is touched, the
timer starts all over again...

How long it takes for it "to go to sleep" I am not quite sure, but 60 minutes should be enough....=;o)....Rest current should be under 0,05 Amps (50ma)

For comparison my 1997 LS400 has a rest current of 24,8ma.

[harrylime]

I removed the boot light a few weeks ago. I am not using remote opening for the doors. having researched online, I just kept the meter connected for a few minutes, to allow everything to go to sleep.. After a minute or so, the draw dropped to 1.25 amps, but then remained constant

[plexus914]

It doesn't work like that.....car won't go into sleep mode whilst measuring rest current.

And, keep in mind you have to take care of the engine hood courtesy switch to arm the theft deterrent system.

[ColinBarber]

It doesn't work like that.....car won't go into sleep mode whilst measuring rest current.

sure it will, how would it know?

Even if the system isn't fully asleep you shouldn't be seeing 1.25 Amps after a few minutes. For that age of vehicle you shouldn't really see more than 100 mA.

Attached is the official Toyota training for batteries and testing - see pages 17 & 18.

elec03.pdf

Worth checking for surface discharge too. Depending on the Battery design this can be quite high if the Battery top becomes dirty or damp.

[plexus914]

Maybe this will help!?

Procedure of how I did it and got a reading of 24,8ma (I went back to the car after about one hour):

- Turn ignition off and pull the key

- Close all doors

- Open hood and close hood lock with a screwdriver

- leave the Battery connected and arm the anti theft deterrent system either by key or by key fob.....and check security lamp that it is on

- to be sure leave the car alone for about 30 - 60 minutes

- go back to the car and measure rest current without interrupting the current (otherwise alarm goes off).

Before disconnecting the Battery put the pair of test leads (black one/-)to the negative Battery terminal and the other (red one/+/A or

ma) to the negative terminal clamp.......now disconnect carefully terminal and clamp.

[ColinBarber]

yes this is the best way to do it although leaving for an hour is excessive, 10 minutes is sufficient.

Most multimeters will only measure a maximum current of 10 Amps, and it is normally fused, so you only want to break the direct connection between the Battery and the terminal once the ignition is off and without headlights on etc.

If you get a high reading then repeat the test without locking the vehicle and arming the alarm, and turning off the interior door lights. Then you can open the door and pull fuses to see which circuit(s) are drawing all the current to narrow down where the problem is.

[harrylime]

Thanks guys, I will try that. Where is the bonnet lock/switch?

[ColinBarber]

It is in the bonnet catch, it senses when the bonnet is fully closed. Not sure if the LS gives you a warning light on the dash when the bonnet is open? That is an easy way to make sure you have defeated it correctly by making sure the light goes out. Alternatively if you try and arm the alarm it may give you the open door warning beep.

[harrylime]

Thank you Colin