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Parasitic Electrical Drain

Battery going flat over a few days of the car not being used?

Modification Details

What Is A Parasitic Drain?

It's a common term for an electrical item that uses more electricity than it should do or isn't turning off when
it should. This could be because of poor design or, more likely, a fault with the item or the wiring to it.

More often than not, if you have an aftermarket alarm fitted, this is what will be draining your battery.
The 2nd highest offender is badly installed amps or powered subs that don't turn off with the ignition.

What Are The Symptoms?

Over a few days of not using your car, you'll find it doesn't have enough battery power to start the engine.
Assuming that your battery is in good condition and you didn't leave the lights on, you have a parasitic drain.

Is There A Quick Fix?

You can try fitting a solar battery charger in an attempt to charge the battery faster than it's being drained.

How Can You Find The Problem To Fix It?

Most people just assume that you'll have to strip the car to manually check the wiring or randomly replace
things, hoping it'll fix the problem. Neither of these are ideal so we'll have to use a different method.

What You'll Need

This is a short list. You need a multimeter. You can get them very cheaply. If you have a helper then you
can use the leads that come with it. If not, you'll need some new leads with large crocodile clips on them.

Setting Up The Multimeter

The normal outputs for a multimeter are as shown below. This is for testing voltage and resistance.

For testing amps, you'll need to move the live (red) lead over to the fused input.
My multimeter is rated to 10 amps but some cheaper/smaller meters are rated to 5 amps.

You will also need to select mA (milliamps) or A (amps) if your meter doesn't automatically select the correct range.

Here is my multimeter with the crocodile leads fitted.

Running The Test


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