Dead Battery Syndrome

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Categories: MR2 Mk2 Articles -> Electrical

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[url=https://www.imoc.co.uk/app.php/kb/viewarticle?a=74&sid=8e439c192edabe84d3415619cd44a187]Knowledge Base - Dead Battery Syndrome[/url]

I returned from a 2 week holiday to find the battery on my MR2 MK2 as dead as a dodo, oh fishhooks!

A new battery was fitted , £30, don\'t beleive all this guff about special batteries. If a bog standard battery doesn\'t do the job you\'ve other problems.

I connected the positive lead to the battery, then joined the negative lead in series through a multimeter on the DC Amps range. Oh dear 0.25amps and no lights etc on. This will soon make a battery useless. ie 1 amperehour every 4 hours. 60AH battery from full charge to zero in 4*60=240hours, or 10days!

On reading IMOC Electrical I was supprised that I was unable to find what the base current should be, and many articles suggesting fancy batteries. Lets be serious, if the base current is such that it will run down a battery in a month or so, then there is something adrift and needs sorted.

Pull the fuses, one at a time, and check the current draw, replace the fuse and move on to the next one.

I was stuck without a circuit diagram, this is where I found links from IMOC really useful.

The problem was a duff Alarm ( It is under the passenger side headlamp. Jack up car,remove wheel, little plastic cover, and some of the plastic wheel arch). Ok it is a bit of a pain but a mans got to do....

Without the alarm the base current dropped to 0.02 amps (20 ma)ie roughly 100 days before dead battery,that seems right enough.

Fit new Alarm, job done , no problems since.

I trust this will be of some use to any MR2 owners with a dead battery syndrome and no obvious reason, ie lights left on or boot switch stuck etc.