parasitic drain dilemma NGC

[lucian]

A question for all the electron savvy members. I have a construction Lull that has a parasitic drain on the battery. We have been just disconnecting the negative terminal from the battery when we are done with it so the battery doesn't go flat. I can clearly see a faint spark when connecting the battery cable so there is obviously something drawing power even though everything electrical on the machine is turned off.
Is there a logical approach to chasing this down? I thought I would try pulling the fuses one at a time and then see if the cable still sparks on reconnection. I do have a multimeter  , but lectricity is  definitely not my strong suite.  TIA, dave

[Tom H]

Could there be something that stays on like a voltmeter, clock or the like? If it has an ECU, they draw power even with the key off.

Tom

[lucian]

thanks Tom. it's a really basic machine electrically. Not really any thing crazy but a windshield wiper, a fan and the ignition system. ( diesel) There is a few electrical solenoids and such related to the hydraulics , and a back up beeper but everything works as it should when operating.   

[lucian]

Sorry , no motorcycle content . It's a construction forklift with the ailment.

[Huzo]

I would get a sensitive zero centre ammeter and put it inline with the battery cable to register discharge.
Turn on the key to witness the flow and start pulling fuses one at a time.
It won’t definitively tell you what it is, but will tell you a lot of things that it isn’t.

[lucian]

I would get a sensitive zero centre ammeter and put it inline with the battery cable to register discharge.
Turn on the key to witness the flow and start pulling fuses one at a time.
It won’t definitively tell you what it is, but will tell you a lot of things that it isn’t.

Thanks Huzo, I think my multi has an amp setting. I'll give it a try this weekend. Hope you're getting along well on you're adventure .

[Tom H]

On Huzo's note. I found this that I think was about a BMW:

 "Disconnect the battery negative wire and connect your multi-meter (on amps) between that wire and the battery negative post.
This will show clock draw + any other parasitic draw you might have.
Meter should read 0 if clock is disconnected and somewhere around .003 if clock is normal."

Most meters only allow up to about 10 amps IIRR. So be careful or be prepared for a new fuse in your meter or a new meter.

My '62 F100 has a draw of IIRR .05 amps. There should be nothing that draws power with the key off. But....this could be an issue with you?.....My accessory 2" Amp Gauge is always working/on even with the key off. It's wired between the battery and the main electric wires to the cab/key switch. It will not show starter draw the way it's wired. This is where "I" think my draw is at. Need to adjust some wires to find out.

With an old battery my truck had starting issues if I left the negative wire on the battery. New battery I can leave it connected.

Tom

[lucian]

Thanks tom,  I found an old automotive amp meter in my chests and will try that one first just encase the draw is something bigger than my multimeter can handle  . Appreciate the help! 

[Tom H]

  Wise move

Tom

[lucian]

Thanks RK> it will kill the battery overnight if left connected. There is clearly an small arc when tapping the negative cable onto the battery posts. Sounds like its a prosses of elimination game I guess. The key switch itself is suspect as it's old and worn out with the key. I though about jumping the starter with the key off just to see if it fires . 

[Tom]

Kill switch to positive terminal???

[Kiwi_Roy]

The problem is measuring the current with a multimeter if it's anything significant or you accidentally turn a load on it will blow the fuse in the meter then you really have 0 milliamps because the meter is open circuit.
One thing you can do is connect the battery it in series with a small 12 Volt incandescent lamp that will indicate any significant current by lighting up.
if it doesn't light up you can then connect your meter in series with the light, it will protect the meter fuse,

[reidy]

This is my logic. You can only have current flow if there is a path from positive to earth. Therefore if you have the positive and negative both disconnected you should have a completely open circuit. If not, and you have a wire diagram please post it so we can give you some suggestions.

Steve 

[Kiwi_Roy]

This is my logic. You can only have current flow if there is a path from positive to earth. Therefore if you have the positive and negative both disconnected you should have a completely open circuit. If not, and you have a wire diagram please post it so we can give you some suggestions.

Steve

Yes or even a make/model No so we can search it out.
Does it not have a key switch to prevent tampering?

[lucian]

Thank you gentlemen for the replies and direction. I'll have a chance tomorrow to spend some time on it and will report back with any progress. Many thanks!!