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I have a Misubishi Canter, it's over 4 years old. I have had problems with the battery draining since new. I had 4 batteries in first 3 1/2 years, the next lasted 4 months, then 2 weeks, then 1 week, now it won't stay charged for a day. I have bought good batteries, had it checked out in many workshops, it's been to electrical specialists and no one can find anything wrong. Anyone got any ideas as to what could be draining the battery?
 

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Look for something staying on in the car. Underhood, trunk or glovebox lights, aftermarket radio/amplifier, alarm systems, radio/car theft LED's, keyless entry, LOJACK, OnSTAR, cell phone.

Maybe the GPS tracking device the FED's installed in the car!

Most new cars have some parasitic battery draw due to the radio station presets and clock, the engine/body control computers, keyless entry modules.

To test this correctly, you need a digital meter with a 10 Amp scale.

Disconnect a battery cable and connect the Amp meter in series and measure the battery drain. It should be under 250 mA, more in the area of 100 mA or less. If you have a draw, start pulling fuses, one at a time to indentify the circuit that has the draw.

But the other thing you need to do is check the battery charging Voltage with the engine running and the headlights on. You should have between 13.8-14.5 Volts at the battery terminal with the engine at an idle.

Post back your parasitic battery current draw.

JamesO
 

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Good suggestion from James. If pulling fuses doesnt stop current draw, check all battery cables and disconnect main battery lead from alternator. Be careful as lead will be live. It is possible you have a minor short circuit in the alternator. This could be a temperature related short in the alternator. You may need to check with engine hot and cold.
 

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I had a neighbor who's battery kept dying. No one could find anything wrong with the battery or charging system. Turns out the radio was defective. It kept the clock display on, even when the car and radio were turned off. He thought the display was supposed to be on all of the time. Just one of the little things that can pop up.
 
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