Battery woe

[Winkle Bill]

Hi everyone,
I'm new to this forum, to any forum for that matter. I bought my Land cruiser last year, my first adventure into 4x4's. I've had no troubles until 3 months ago, after leaving my truck for a couple of weeks to find flat batteries on my return.. The mechanic at my work tested the batteries and informed one of them was defective showing only 5-6 volts output, the other showing 13.4. I replaced the defective one but ever since if I leave it for a few days I have flat batteries again.. Does anyone have any ideas what may be draining them please
Winkle Bill

 

[Gary Stockton]

Welcome. Best to get a tester in and check drain on them - also look for faulty wiring.

If you have an after-market alarm / immobiliser, get that checked too.

Cheers

 

[SpinDrift]

Hi and Welcome.

It is generally recommnded to change both batteries at the same time as if one of them is defective, it is more than likely that it would have a detrimental effect on the good battery. Ideally you should change the second one now.

Having said that, it is possible that you have a short somewhere in the system. You could disconnect the batteries while the vehicle is not in use to see what happens. There is always a drain on the batteries because of clock, alarms etc and two weeks is a long time of one of the batteries is defective.

Alternatively you could do some trouble shooting with a multimeter and one of these http://www.maplin.co.uk/car-fuse-adaptor-lead-set-217881 With the engine and everything switched off, open the fuse box (in the engine bay and in the dash) and pull out the fuses one by one, inserting the fuse into the adaptor and plugging the lead into the fuse box to see if there is any unexplained current drain. You are looking for very low amounts of current - but overtime they will kill the batteries.

cheers

Reinhard

 

[Winkle Bill]

Thanks for the advise, I've just received the adaptor lead set so all set to test my circuits.. One problem, I have an analogue multimeter, (rapidest 7040) but no instructions.. What setting should I have it on??

 

[Graham]

Hi Bill,

If you are testing the DC voltage of your batteries, then 50 v dc

Black lead in the center, and the red lead to the right.
Red lead on pos termnal, black lead on neg terminal.

If your looking to measure battery drain, then start on 10 amps.
Black meter lead in center, red lead in left hole.
Meter pointer to 10 amp scale.

If there is no meter deflection, then go down a scale to 500mA.
500mA = half an amp.
black lead in center, and red lead in right hole.

Now, under no circumstances, put the leads across the battery terminals pos and neg, while measuring mA or amps.
The fuse will blow in the meter if your luck, if your unlucy, the meter will fry

If you cant see any meter deflection, ie, red lead on pos of battery, and meter black lead on the cable that you have took off the positive terminal.
Ignition off, keys out.

let us know what the drain is

Gra

 

[Winkle Bill]

Thanks Graham, much appreciated

 

[Winkle Bill]

Thanks Graham,
what I'm trying to find out is why my batteries are going flat if I leave it for more than a few days. My local garage checked batteries and said both ok and alternator is charging, so something is obviously draining the power. The only thing I can think of is the courtesy lights in the cabin do not come on when you open the doors (only the one in the boot), though they do work manually i.e. switch them on they illuminate, shut the door and they go out, open the door again and ....nothing. I should add that at some stage it has had an aftermarket central DVD monitor/light combo fitted (DVD works fine).. I should also add that whilst I'm quite handy on diy repairs etc, I can never seem to get my head round electrical problems so I won't take offence if you want to treat me like a muppet to explain it to me

 

[Graham]

Hi Mike,

How did he test the batteries?
They should really be tested with a high current drain, andwhile the high current is being drained out of teh battery, the voltage should be noted.
Each battery need disconnecting completly from teh LC, and each tested seperatly.

I guess the next step is when you are home, completley disconnect either left side battery, or right side battery, and insulate the 2 terminals on the ends of the cables, one runs to chassis some where, the black one, and the other that go to the starter motor or some where, maybe a starting relay, it doesn't matter, but just insulate it so no chance of it touching any thing else AT ALL.

Then working on the battery that is still in connection, with teh LC electrics.
Make sure teh key is off, and for good measure, pulled out of the ignition.
Then loosen the posative (red) lead on the battery.
Put the test meter to the 10 amp scale, put the black lead in teh middle hole, and teh red lead in teh left hole.
Connect the black lead to the red terminal that you have took off the batterries posative teminal, and make sure it doesn't touch any thing.
This is where the 3 hands come in handy.
Then briefly touch the red lead of the test meter on the posative terminal of the battery, if teh needle pointer swings hard over to the right, then stop as fast as you can, as it is taking too much current (amps) through teh meter to the LC electrics.
If the needle hardly moves, which is most probable, then keep the two meter leads connected.
You can hold the leads on teh battery, you wont get a shock
You can also hold teh black lead on the battery lead going to the LC electrics, you wont ge ta shock.

Then look at the 10 amp scale, and see if you can read how much current (amps0 is indicated.
Hope fully it will not move the needle pointer at all.
if teh needle pointer is pointing to half an amp or less, then you can repaet the test, using a lower scale on teh meter.

Remember to swap the red lead on the meter from the left hole on teh meter to the right hole on the meter.
Then turn the pointer to the 500mA scale, which is just 1 step clock wise from the 10 Amp scale.
By using the 500mA scale, which is half amp, you should be able so see the slight drain of the imobiliser and the radio permanent feed.
I don't know the amps of the inside lights, but opening a door, may send the needle hard to the right, if your on teh 500mA scale.

For information, without getting too technical,,,,
a 12 watt bulb uses 1 amp at 12 volts supply
so a 6 watt bulb uses half amp at 12 volt supply
so a stop lamp, which is 21 wats, is ,,,,,,,,,,,,,,21 divided by 12 = 1,75 amps.

so if your door lights are 5 watts, or some thing like that, they will draw close to the meters maximum when on the 500mA (half amp0 scale.

Gra.

 

[Winkle Bill]

Graham,

thanks for that, if the rain holds off tomorrow I'll be out and testing things. I'll let you know how I get on

 

[Crispin]

Now, under no circumstances, put the leads across the battery terminals pos and neg, while measuring mA or amps.
The fuse will blow in the meter if your luck, if your unlucy, the meter will fry

All as Graham says, but to add:

Also, be careful of turning the ignition on. Glow plugs could cook the meter as they heat up, an 80's pre-heater would not be too friendly with the meter either.
Best case - the meter pops a fuse. Worse case - the leads melt into your hand. I worked with a chap who melted his wedding band onto / into his finger because of a short.

 

[Winkle Bill]

Thanks Guys

 

[Graham]

Hi Bill,
Just as Crispin has also said about the ignition off.

Better to put the keys in your pocket maybe, if your a forgetfull person like me.

After 35 years of electrical work, I have boobed on the odd meter here and there, just through not thinking.

Gra.