Any tips for locating a current leak?
 

The new battery on my 1997 XT600 is losing charge even though everything on the bike is turned off. After two weeks away I came back to find the normal 12.7V had dropped to around 8.

It also drains when I have the lights turned on while riding – voltage drops from 14.7 to 12.7 as soon as I turn them on and carries on draining slowly all the time they are on.

My uneducated guess is that these issues are related and caused by a dodgy connection somewhere. I’ve been doing some work on the electrics recently, including fitting a new headlamp, so it is very possible that one of my crimped connections isn’t up to the job.

My question is how do I find it? I’ve been reading about voltage drop testing and testing by connecting a light bulb across the fuse and wiggling the connections but are either of these likely to work in my situation? I’m expecting this to be a long, frustrating job so any guidance would be much appreciated.

Edit: I've just been checking the current flow at the battery and it looks like my Koso digital speedo (which is wired directly to the battery as per the instructions) is drawing around 0.8mA when everything is turned off. Is this normal?

Battery just could be dogdy. Anyways 0,8ma(miliamps per hour) is NOTHING. You have around 9000mah in your battery.


1) Have you tested if the battery-voltage stays stable when removed from the bike? Otherwise the battery is dead.
2) Loadtest the battery. Check voltage with bike off, and compare the voltage with and without lights on. Also check voltage when cranking the starter.
3) Check Ohm on the wires from the stator (specs in manual)

If thoose turn up fine, you have a bad rec/reg. They can be had pretty cheap on ebay. The later models have cooling-fins on the rec/reg, be sure to get one of thoose as they are better by design.

Make sure that the battery is recharged, cause trying to diagnostice a charging problem with a battery with one leg in the grave can cause all sorts of foul readings.

Thanks Jens. The battery is a Varta and is only a month old. Do you think the fact it discharged so much might have permanently ruined it?

Yes, I think a 12V battery with 8V on it is ruined. Anything less than about 12V won't come back in my experience. It will take a charge and look like it has 12V or so on it but that will quickly drop back - even if it is off the bike.

Bike alarms (for example) use the right amount of low current to deep discharge a battery over a few months. My rarely ridden ex-wife's SV650 killed 3 or 4 batteries in a row before I removed the alarm. Job done then and it was fine not used for months after that.

Had the same problem with a b---stard data tool alarm. got rid of it. Bike much nicer to live with now :)

To test battery, charge it up then disconnect one side (earth) or teh other so the battery terminal has no wires on it, wait to see if it discharges itself, if so you need a new battery. if not the something is stealing power.

Transponder keys left in the ignition of the bike 'talk' to the bike and can also drain the battery (not sure if applicable to your bike- seems a bit old). And I've had a USB plug that drained power off my battery as well. It didn't switch off the 12V-5V circuit so just kept draining

As for how to find if its a short or similar - I start by disconnecting the battery terminals and connect an Amp meter in series to the battery and harness (everything is switched off on the bike). If there is current draw, I start by removing one fuse at a time till the current draw = 0. And that circuit is the culprit circuit that requires further inspection and attention

Thank you for the advice. I've had the battery off for 24 hours and the voltage hasn't changed from just below 12.8 V. Can I ask how long would you expect it to take to show a current discharge, if the battery was faulty?

As suggested I've also checked for current draw and it is 0.8mA until I disconnect the digital speedo, when it drops to zero. As Jens pointed out this is not enough to affect the battery so I'm totally mystified as to what caused it to drain in the first place.

A battery can have volts but no capacity. An internal short makes it a smaller container for charge, think of it like putting a knot in a toy balloon then trying to fill it with water.

I'd charge it up, put it on the bike with the digital clock disconnected and see what happens. If it holds 12.8V put the fuse back and see if it drains overnight.

The battery is 9000 mAh and the drain in 8mA so it takes 9000/8 hours, so about 5 weeks in theory. In practice it might be under a month, but it isn't less than a day.

Andy

Yes in harness with many different fuses...On these bikes you need to disconect power to the different components.

Do an Amp draw test. Even cheap meters have the function.

Remove the Neg terminal from the battery and put the meter between the battery terminal and the cable that you just removed. Any reading will show the current draw from the battery.

If you turn on your ignition you will see reading. The reading will change if you turn your lights on etc.

A bike should have zero or near zero current draw when standing. If yours doesn't then you may indeed have a short to earth in one or more circuits.

Remove fuses or isolate circuits until the reading on the meter is zero. That circuit will show you the draw.


P.S. The fuse in the meter will determine what your amp draw you meter can take. Make sure you connect the meter properly. Don't use the starter motor.

Do you mean don't start the bike when the meter is connected? Why because the surge can damage the meter?

Thanks,
Chris

Yes.

Yes. The amp draw on the starter will be greater than the fuse in the meter. Which are usually 10A or less.

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As Ted says, use the 10A input on your multimeter.

And I wouldn't muck about much with the lights either. 2 x 5W sidelight bulbs, a 55W headlight and 2 x 21W indicators is 107W and getting on for 10A.

Thanks for the replies :)