Finding a voltage leak

[mudski]

Is there anyway to do this? I have installed a new battery, 3 months ago, and within a week I'd say, the Patrol seems hard to start in the mornings. Like the battery is dead. It doesn't get driven much, usually sits on a trickle charger, Ctek MXS10, but lately my daughter has been driving it and she's noticed it also.
Upon starting the Redarc volt gauge will drop down to below 12V, where it usually won't.

I have the standard leccy tools, DMM, battery load tester, (which I'll try this first, and maybe get the old hydrometer out and test each cell) But nothing flash.

I'm also wondering if the starter motor could be giving these symptoms, it is 8 years old.

Cheers.

[nipagu7]

check + & - connections at battery , starter & altenator . make sure they are clean from dirt and mud . iron is a common component of dirt and mud and power will track to earth.

[mudnut]

A common place for parasitic draw is the diodes in the Alternator and Regulator in older vehicles that don't use the computer to regulate the output.

Does the starter run at normal speed on later starts in the day, after the battery has had time to charge up a bit?

[mudski]

A common place for parasitic draw is the diodes in the Alternator and Regulator in older vehicles that don't use the computer to regulate the output.

Does the starter run at normal speed on later starts in the day, after the battery has had time to charge up a bit?

The starter motor works fine, just sometimes when you turn the key it feels like the battery.

Is there any way to test using equipment for parasitic draw? One thing I have noticed is that the alternator won’t charge past 12v when cold and it idle. Pull the revs up and it’s fine.


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[mudnut]

An alternator really needs 1500 or so revs to get charging, then will charge at idle. On my old Trol, its easy to check for parasitic draw. With the ignition off just disconnect the battery negative and clip a multimeter in series with it on 10amps. My Q draws a few hundred milliamps for a few seconds to power up the clock, etc. It then dies down to a miniscule amount.

The alternator should put out between 13.8 to 14.3 volts a bit of time after cranking the starter. Even with lights on high and accessories going at 1500 rpm it should stay steady.

On newer vehicles, checking for parasitic draw becomes problematic, as the ECU transmission control, body modules etc all draw a small amount. And its not good to disconnect the battery without a smaller battery to keep voltage present.

If you find that the parasitic draw is high, before diving too deep and pulling wiring apart, you can pull fuses and relays to see if it drops.

[mihit]

^^ This


With the ignition off just disconnect the battery negative and clip a multimeter in series with it on 10amps.

Just for clarity: that could be labelled DCA or DCI, and on most meters you will need to swap the red lead from the "voltage/resistance" plug to the "10A" one.
If your meter isn't auto-ranging, start on the highest current option (10A), if nothing shows up, or you get a reading like "0.1", or a reading that flicks between 0.1 and 0.2, go to the next option which may be 5000mA or 1000mA which will give you greater resolution. ie 0.1234
About a quarter to half amp should be acceptable with a good battery (<250-480mA)

- and don't forget to swap the red lead back immediately you've finished! if you try and measure voltage with them in that configuration you're going to pop the multimeter fuse.


If you find that the parasitic draw is high, before diving too deep and pulling wiring apart, you can pull fuses and relays to see if it drops.

I got one of these which is handy for just that:
86982

[mudski]

An alternator really needs 1500 or so revs to get charging, then will charge at idle. On my old Trol, its easy to check for parasitic draw. With the ignition off just disconnect the battery negative and clip a multimeter in series with it on 10amps. My Q draws a few hundred milliamps for a few seconds to power up the clock, etc. It then dies down to a miniscule amount.

The alternator should put out between 13.8 to 14.3 volts a bit of time after cranking the starter. Even with lights on high and accessories going at 1500 rpm it should stay steady.

On newer vehicles, checking for parasitic draw becomes problematic, as the ECU transmission control, body modules etc all draw a small amount. And its not good to disconnect the battery without a smaller battery to keep voltage present.

If you find that the parasitic draw is high, before diving too deep and pulling wiring apart, you can pull fuses and relays to see if it drops.


^^ This



Just for clarity: that could be labelled DCA or DCI, and on most meters you will need to swap the red lead from the "voltage/resistance" plug to the "10A" one.
If your meter isn't auto-ranging, start on the highest current option (10A), if nothing shows up, or you get a reading like "0.1", or a reading that flicks between 0.1 and 0.2, go to the next option which may be 5000mA or 1000mA which will give you greater resolution. ie 0.1234
About a quarter to half amp should be acceptable with a good battery (<250-480mA)

- and don't forget to swap the red lead back immediately you've finished! if you try and measure voltage with them in that configuration you're going to pop the multimeter fuse.



Thanks guys, most of that went over my head but I will have to wait until the weekend to try. I leave for work in the dark and get home in the dark, and the Patrol doesn't fit in the garage unless the roof rack is off. Winter sux. :wink: