Q&A for How to Find a Parasitic Battery Drain

The ammeter can be connected to either terminal with identical results with one exception: if you get against a metal object while using a positive terminal, there is potential for a short circuit with a shower of sparks. Use the negative terminal - that is safer.

Yes, if it was connected straight to the battery rather than through the ignition. It should only draw a small amount for the clock when the ignition is off. If you can use the radio with the ignition in the off position, you have a problem.

Yes, it can. If checking for a drain, the alarm should be the first thing to be disconnected to see if the drain stops.

Are you sure you checked every fuse? Most cars (especially foreign and luxury cars) have multiple fuse boxes. Consult your owner's manual for locations. A 2004 Saab, for example, has a fuse box in the engine compartment and under the dashboard inside the car.

No. Your car computer, and possibly other components, will activate when the battery is connected. They then go to sleep after a short time, just as they do when you turn off the ignition. A small spark on the connection is normal.

Pull the negative off the battery. Put the test light between the post and the ground wire. If the light illuminates, you have a draw. Use the fuse pull method to find the draw; when the light goes out, you found the draw.

I'd try checking your ground wire on your battery. 12.44v is plenty, and when hooking up the other vehicle on jump leads, the other vehicle is completing the circuit.

Yes it can. Points inside the ignition lock housing can still be closing the circuit, which in turn will leave current flowing, draining the battery.

Put a switch in between the circuit to completely kill the power. Then, when you need to use the van, turn the switch on. Other than that, check your motor for the constant draw.

In older vehicles running analog Onstar, the system will drain the battery because it is constantly looking for a signal. Onstar no longer offers an analog signal, only digital.

If you don't use Onstar, just unplug it completely. Otherwise, you can install a manual switch on it.

You could have a fuse that is draining your battery.

No, a 12 volt battery should read around 12.5 volts with the car off. A battery is typically made up of 6 individual cells at 2 volts each that make up 12 volts. As a battery ages, sulfur builds up on the cells and will eventually short out individual cells. Getting a 10.67 volts typically means one of the battery cells is shorted.

It is possible, as every time it makes a connection, components will activate, preventing systems from going to sleep.

If you pull the lead off the battery while the car is running and the car stalls immediately, it means that your alternator is bad.

Electric seats will draw a lot of current when being operated (little or none when idle).

General Motors says 25 milliamps is acceptable on most of their new cars & trucks.

Could be that the new battery is also faulty. Don't discount that. On BMW's, the battery has to be registered with the charging circuit. Some batteries, like Silver Calcium, require a higher rate of charge than normal lead plates.

Start the car and measure the voltage at the battery. It should read between 13.5 and 14.6 volts when running. if the voltage is is 12v or lower when running, then you're not charging.

Disconnect the ground every evening to be able to start the car in the morning until the culprit is determined.

Check your door switches and the interior lamp dial on the dash. One of them is probably shorting.

If there is no parasitic drain, the current reading should be zero. It might be something other than zero at first, but after a minute it should go to zero.

No, a clamp-type ammeter generally works with the increasing or decreasing field of an alternating current circuit such as in your house wiring. Current meters for direct current are put in series with the conductor whose current needs reading.

Look up the specific sensor and then see what to check or replace. Usually they have a sensor code on it to look in the manual.

This is highly unlikely. It's possible only if it's hooked into the car's electrical system and it's drawing more than 25 mA with the car not running.

Most of the starters and alternators we buy are simply refurbished, which is part of why they're cheap and almost always require a core. It's possible that the "new" alternator you got was not in very good shape to begin with.

There is nothing to worry about. There should be no power on the circuit, so no damage can be done.

A fuse is a circuit breaker that protects auto-electrical circuits from electrical problems, like electric surges. Normally, fuses can also be classified as one of the factors that contribute to parasitic current. Fuses have different amperage ratings depending on what circuit is protected. A fuse that has a higher amp. rating can contribute almost 10 amp, even if the circuit is off.

If there is a draincock on the battery that was not there before. Remove the battery and inspect for any draincocks installed.

The UCH (Unite Centrale Habitacle) is an electronic control module that is fitted to many late model Renaults. It is responsible for controlling many of the non-engine related functions of the car, such as central locking, electric windows and even some of the lights.