How do I take a reading from a battery analyser?

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Q. After electrical problems with my Citroën C3 Picasso I bought a battery analyser, but the device has come with minimal documentation. How can I take a reading? JL, Cardiff

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A. Keeping an eye on the condition of your battery is a good idea, especially given the fussy nature of many of the electronic devices found in modern cars, notably the “brains” of the vehicle, the ECU. To take a reading, you will need to connect the analyser to the car battery’s negative and positive terminals.

The Picasso’s negative terminal is not immediately accessible. However, any non-painted metal part of the vehicle will serve, as long as it is clean. Connect the red lead of the analyser to the positive terminal — easy to get at on the front of the battery, under a plastic flap — and the other to a metal part: try the engine block itself.

Check the reading against the battery spec. For a car the size of yours, it should show about 60-64 amp hours (Ah) and a cold cranking rating — the current the battery can supply — of around 540 amps.

There’s not much you can do for maintenance, as almost all batteries are sealed, but the analyser will at least let you keep track of any changes. Batteries don’t like the cold, so parking in a garage or close to a wall to reduce the effect of wind chill will help conserve its charge. And make sure that the terminals (or in your case, the one you can see) are clean and show no sign of furring up.

Sunday Times Driving Car Clinic: Dave Pollard, car accessory advice

Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory – read more from Dave here.

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