Finding current drain

[want33s]

I have just bought a GQ turbo diesel wagon. One of the problems it has is it will drain both batteries in 2-3 days if not driven.

Q: How do I find the source of the current loss?
I have load tested both batteries and they appear to be fine.
I have a multimeter.

Thanks... Jas

[ledgend80]

if you can get hold of a clamp meter they make it a bit easier as you can put it over individual cables to check. also what mods or accessories are fitted

[want33s]

It has dual batteries with a Redarc setup.
Also has UHF, extra power outlet in rear and a heap of accesory gauges for boost, exhaust temp etc.
I don't have access to a clamp on current meter.

[murcod]

I'd start by isolating the aux from the main battery (by disconnecting the redarc inputs.) Then see if they both still drain or if only one does.

[BASSYK]

put your multimeter on Current ( DC A =) and remove the battery terminal and put the meter between the batt terminal ant the terminal with all your wires (with the car switched off) and this will tell you how much current you are dragging

then you need to isolate the circuits and find which one is dragging most of the current.

thius can be done by removing each fuse one at a time and putting the meter across where the fuse was (still on current) and seeing if any of the circuits are draining most of the current found in test 1
if that doesnt show up anything then you will need to start finding all the aftermarket wires and disconnecting them 1 at a time and doing the same test.

[Thylacine]

put your multimeter on Current ( DC A =) and remove the battery terminal and put the meter between the batt terminal ant the terminal with all your wires (with the car switched off) and this will tell you how much current you are dragging

then you need to isolate the circuits and find which one is dragging most of the current.

thius can be done by removing each fuse one at a time and putting the meter across where the fuse was (still on current) and seeing if any of the circuits are draining most of the current found in test 1
if that doesnt show up anything then you will need to start finding all the aftermarket wires and disconnecting them 1 at a time and doing the same test.

Most dmm's only have a 10ADC range and will blow up if used to measure excessive current. Unless your meter has a 50ADC+ range I would strongly advise not using it in such a fashion.



ed

[want33s]

I charged both batteries and have been busy fixing other stuff to get it ready for RWC.
Started easy this afternoon after sitting for 36 hours.
Will start testing each fuse tomorrow.

[murcod]

put your multimeter on Current ( DC A =) and remove the battery terminal and put the meter between the batt terminal ant the terminal with all your wires (with the car switched off) and this will tell you how much current you are dragging

then you need to isolate the circuits and find which one is dragging most of the current.

thius can be done by removing each fuse one at a time and putting the meter across where the fuse was (still on current) and seeing if any of the circuits are draining most of the current found in test 1
if that doesnt show up anything then you will need to start finding all the aftermarket wires and disconnecting them 1 at a time and doing the same test.

Most dmm's only have a 10ADC range and will blow up if used to measure excessive current. Unless your meter has a 50ADC+ range I would strongly advise not using it in such a fashion.



ed

You'd have to have some serious current issues for there to be over 10 amps being drawn with everything OFF!

The worse case (if there was more than 10Amps) is the internal fuse inside the multimeter would blow. And if the multimeter doesn't have an internal protection fuse then throw it in the bin and buy a decent one!

[Thylacine]

You'd have to have some serious current issues for there to be over 10 amps being drawn with everything OFF!

Definitely

The worse case (if there was more than 10Amps) is the internal fuse inside the multimeter would blow. And if the multimeter doesn't have an internal protection fuse then throw it in the bin and buy a decent one,!

Worse case - you're meter is screwed. Quality or crap meters, doesn't matter, the 10ADC internal fuse is poor protection.





ed

[DamTriton]

Working backwards a bit, if you are losing say a total of 100 amp/hrs of charge (normal "flat" batteries unable to start vehicle) over ~36 hrs this would indicate a load of about 2.5-3 amps. Your standard multimeter should deal with that OK, with a bit for headroom if it is a bit more.

Don't discount having a bad cell in one of the batteries bringing both the batteries down in charge....

[SteelArt]

When I am checking for a current draw / dead loss I have a lead with a clip on both ends and a spade fuse holder in the centre. I have a 5 amp fuse in there and if it goes pop them my meter is safe and I know I have an issue as normally I am looking with everything turned off.

[chimpboy]

I buy multimeters in boxes of twenty for exactly this reason.

[stuee]

I agree with murcod that the easiest bet would be to disconnect the batteries from each other first after charging and see if only one dies or the other.

Just have to check voltage with a multimeter just after you disconnect them and then again in the morning after letting them sit overnight.

Once this is done you've either identified a dud battery or halved the potential circuits that could be draining you batteries.

Other possibilities are the redarc could be naff, or if both still loose charge after disconnecting the redarc the wiring could be incorrect also (or 2 dud batteries...)

[-Scott-]

You'd have to have some serious current issues for there to be over 10 amps being drawn with everything OFF!

Definitely

The worse case (if there was more than 10Amps) is the internal fuse inside the multimeter would blow. And if the multimeter doesn't have an internal protection fuse then throw it in the bin and buy a decent one,!

Worse case - you're meter is screwed. Quality or crap meters, doesn't matter, the 10ADC internal fuse is poor protection.

OT, but:

My cheapy multimeters simply have a copper strip between the 10A current input and the common connection - presumably calibrated.

I've used this connection to short my battery (not intentionally, of course ) and only figured it out when the display went over-range and the leads became very hot.

Nothing went pop, nothing broke, although I wouldn't be surprised if the "calibration" is no longer correct - but I'm not doing anything which requires NATA traceable accuracy, so WGAF?

Back to the topic:

If you're really worried about using your DC ammeter to look for "leaking" circuits, put a brake light bulb in series with the meter - if you have a direct short somewhere, the bulb will light up and current will be limited to around 2A.

[Thylacine]

My cheapy multimeters simply have a copper strip between the 10A current input and the common connection - presumably calibrated.

I've used this connection to short my battery (not intentionally, of course ) and only figured it out when the display went over-range and the leads became very hot.

Nothing went pop, nothing broke, although I wouldn't be surprised if the "calibration" is no longer correct - but I'm not doing anything which requires NATA traceable accuracy, so WGAF?

Comment was made regarding worse-case scenarios, not best. I'm an industrial Instrument Eng, and have questioned Fluke fuses on many occasions.





ed

[BASSYK]

if it is such a drama borrow a bloody clamp meter!

[murcod]

I'm not going to get into the "name dropping" scenario, but I work with multimeters everyday.

I can also claim the fame for recently "stuffing up" while checking current drain on a vehicle battery. I had a large spike while on one of the lower current ranges go through my own meter (I forgot the indicators all flash when I armed the alarm......) It's not a mega expensive meter, but survived it with only a blown fuse.

I've also lost count of the number of times I've gone to use the current setting on the Fluke/ Tektronix meters at work and the internal fuse has been fried by some clown. Replace the fuse and they're fine.

[presto]

any luck tracing the drain yet?

[Thylacine]

I'm not going to get into the "name dropping" scenario, but I work with multimeters everyday.

I can also claim the fame for recently "stuffing up" while checking current drain on a vehicle battery. I had a large spike while on one of the lower current ranges go through my own meter (I forgot the indicators all flash when I armed the alarm......) It's not a mega expensive meter, but survived it with only a blown fuse.

I've also lost count of the number of times I've gone to use the current setting on the Fluke/ Tektronix meters at work and the internal fuse has been fried by some clown. Replace the fuse and they're fine.

I'm obviously being a bit anal with this, and would happily use my own Fluke (and I don't work these days so if I kill it, it's my expense) on 99% of automotive fault-finding.
My comment was in regard to correct procedure.
As per posts in another thread, this information is read by complete novices so should be as factual as possible. People with enough understanding to correctly perform their own fault-finding will understand which situations are inappropriate for the 10ADC range whereas those that need to ask such questions may not.

Murcod, whats trade on Fluke fuses these days? I remember getting queried by my boss as to my expenditure on fuses. Someone mentioned using the last spare so I ordered 2doz next time I was buying stuff (without checking the price - there's a lesson there). This was 15odd years back and I think they were about $50-$60 then.





ed

[-Scott-]

Murcod, whats trade on Fluke fuses these days? I remember getting queried by my boss as to my expenditure on fuses. Someone mentioned using the last spare so I ordered 2doz next time I was buying stuff (without checking the price - there's a lesson there). This was 15odd years back and I think they were about $50-$60 then.

About 5 years ago I had to order Fluke fuses, and was horrified at the prices - but they weren't that extreme.

From memory, after some hunting around on the 'net, I found the part I required for about $12 ea for 5 - but most were in the $20 - $30 range.

[want33s]

any luck tracing the drain yet?

Nah not yet Presto, too busy reading all about multimeters
Been flatout with work and then when I get home been busy chasing up parts needed and fixing all the stuff I DO know how to fix.
I'm working my way through a list, so will get there soon.

I did get 15 minutes to pull all the fuses and check for DC A at them but every one read 0.00 flashing to -0.00. No result... will have to look at all the aftermarket wiring.

Thanks for all the tips guys. Will post the result as soon as I know

[Pajero 4D56]

Hi mate....try to put a Bulb in series.....disconnect the Negative lead from both battery and connect either one side of the bulb terminal to the battery Negative lead,put another terminal to the battery negative terminal and a setup is complete

See if the bulb is lit up or not,if it does lit then theres is a short somewhere,when at the engine bay pull the Alternator connector or unbolt the LIVE wire from the Alternator,see if the light goes out,if it does goes out then the Alternator is fault and needs replacing

If the light remains,get inside and pull the fuse one by one until the light goes out,this will indicate which component is short,if the bulb also don't wanna to goes out then something that are not wired via fuses are short,this is a big possible of aftermarket device which installed later after the Vehicle is built

To confirm this,look at the Battery Positive terminal to see wheather there is some wire connected to the clamp bolt,disconnect the bolt and see if the light goes out,if it does goes out and if the lead is more than one,put back one by one to make sure which wire is shorted

Do the test before attempt to check those wiring,this will save you alot of time

[MattF]

See if the bulb is lit up or not,if it does lit then theres is a short somewhere

Load and short are different things.

[want33s]

Found a fairly major problem and rectified it this morning.. Still not sure all is right now but should know by tomorrow morning..



Turns out (after having the batteries tested AGAIN) that one was dead and the REDARC was wired incorrectly. Both batteries were joined together so dead one was sucking the life out of the good one.
Hopefully that problem is sorted now and I can get back to the other stuff that needs doing.

[chimpboy]

That would certainly cause all manner of problems!