Gongladosh wrote:

Cheers guys.

What's the best way to track down a power drain?

BogMonster wrote:

Gongladosh wrote:

Cheers guys.

What's the best way to track down a power drain?

Disconnect one of the battery terminals and put an ammeter between the battery post and the terminal - a normal multimeter on the 10 amp range is all you need, though it can be a faff to set it up so you can go off and do other things. One option is to do it on the battery negative and use a couple of hose clips to clamp the multimeter probes onto the battery post and the negative terminal.

You'll see if there is a measurable drain. On a vehicle with an alarm/clock etc this is usually of the order of 20ma (0.02 amps). On an older vehicle with no 'sleeping electronics' it could be down to effectively zero. Persistent problems with flat batteries usually result from a drain of 0.1-0.5 amps or more, which is easy to identify. If there is a drain, go through the fuse box and pull the fuses one by one until the drain disappears.

When that happens you know what is sucking the juice so work through that circuit and/or replace whatever is on the end of it. If it doesn't disappear after all the fuses have been pulled, it's something that isn't fused, and the most likely culprit in that case would be the alternator, or something else (like the tracker mentioned in an earlier post) which may be connected directly to the battery. A dud alternator regulator can often suck a couple of amps which is more than enough to flatten a battery in a day or two.

Remember to disconnect the ammeter before you turn the ignition or any high-load things on otherwise you will hear a pop and quite possibly need a new ammeter. No prizes for guessing how I know that.

A solar panel as shown above is a good solution. My father uses them in a couple of vehicles. Just be aware that on some vehicles the cigarette lighter socket is switched with the ignition, which means the ones that plug in there don't work with the ignition off. Depends on the vehicle.

^^^^This advice is spot on and exactly how I have traced such faults myself in the past (but without blowing up my multimeter )

Funnily enough, like another poster above, the vehicle that I really had a bad problem with was my old Jeep Cherokee that turned out it had some kind of commercial vehicle tracking device fitted from the first company owners. Fine if the vehicle was used regularly but would flatten the battery in 7-10 days.

Like ^^he said, idle standing current drain should be 15-20mA or less. Doing the maths suggests a 15mA draw will flatten a fully charged 70Ah battery in around 195 days or approx 6 months! That should be long enough for most of us.