Mazda MX5 - Battery failures

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Mon 24 Mar 2014 17:27
Mazda MX5 - Battery failures - TrevW

Bought a 3 month old MX5 from a franchised dealer on 31/12/13, only 65 miles on clock, allegedly a demo car. Every 2 weeks it fails to start and battery is dead. Been in local Mazda dealers for a total of 5 weeks out of the 11 weeks i have owned it, it has had 3 batteries and the latest one has just failed again. Dealer can find no drain on battery, but something is clearly draining it and presenting itself as a faulty cell on the battery. Car is used every day (when it starts) for 10-30 miles, exactly same usage as previous Mini which ran faultlessly for over 8 years with same battery. Garaged and locked with immobiliser on overnight. No lights etc left on or doors open. alternator tested and works fine. Made clear to dealer that they need to do something different to previous times but not convinced they know what to do. Have also advised the selling dealer that it is not fit for purpose. Any advice gratefully received, Thanks in advance.

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Mon 24 Mar 2014 20:10
Mazda MX5 - Battery failures - bazza

This seems to be quite a common problem with the MX5. I had an older one that also suffered sudden battery failure. The battery itself is quite small and often regarded as a weak point. However, something is draining yours. You need to get an ammeter on it plus someone like an auto electrician, who knows what they are doing - not necessarily the case in main dealers. Also the charging circuit itself needs checking for any high resistances giving a poor charge.

In the meantime, a simple solution would be an Optimate type trickle charger, as used by nearly all motorbike owners through the winter months. Bike batteries are also very small and this is the universal solution. There's probably someone who sells an aftermarket upgraded 12v battery as well. I wouldn't give up on such a nice car just yet!

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Tue 25 Mar 2014 07:00
Mazda MX5 - Battery failures - Collos25

Somebody was on this forum with exactly the same problem I believe it was the radio it was waking up in the night and causing battery drain.

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Tue 25 Mar 2014 08:03
Mazda MX5 - Battery failures - elekie&a/c doctor

Or possibly the bluetooth system if fitted.

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Tue 25 Mar 2014 08:39
Mazda MX5 - Battery failures - Collos25

When I say same problem it was the exact same make of car same age same problem radio changed problem gone.

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Tue 25 Mar 2014 10:06
Mazda MX5 - Battery failures - TrevW

Many thanks Collos,I will let the dealer know about the radio idea.

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Tue 25 Mar 2014 10:07
Mazda MX5 - Battery failures - TrevW

Many thanks Elekie, no bluetooth fitted.

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Tue 25 Mar 2014 10:05
Mazda MX5 - Battery failures - TrevW

Many thanks Bazza I'll check that the dealer is carrying out these ideas - disappointing if not after they've had it for 5 weeks!

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Tue 25 Mar 2014 14:13
Mazda MX5 - Battery failures - TrevW

Dealer has had multimeter on for a fortnight and NO drain found at all. Then suddenly dive bombs and battery is dead, showing a fault code on the battery. The battery has shown fully charged each day for a fortnight, i do not understand why, if there is a drain, it does not gradually lose charge.

So without a drain being indicated, the suggested process of removing fuses to see the change in level of drain will not work.

.Any other thoughts or ideas please.

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Tue 25 Mar 2014 18:48
Mazda MX5 - Battery failures - quizman

It's a nearly new car with warranty. Make the dealer fix it, you shouldn't have to tell them what to do. And you shouldn't have to keep charging a new car.

You could perhaps reject it as it doesn't seem fit for purpose. Maybe they would exchange it for another.

Japanese reliability eh!!!!!!!!!!!

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Wed 26 Mar 2014 06:59
Mazda MX5 - Battery failures - Collos25

Dealer has had multimeter on for a fortnight and NO drain found at all. Then suddenly dive bombs and battery is dead, showing a fault code on the battery. The battery has shown fully charged each day for a fortnight, i do not understand why, if there is a drain, it does not gradually lose charge.

So without a drain being indicated, the suggested process of removing fuses to see the change in level of drain will not work.

.Any other thoughts or ideas please.

Exactly the same as the previous post as stated a faulty radio,is the electrician stopping all night or have they a recorder connected to your car.

Batteries do not fail without good reason as previous post if its under warranty the dealer must fix it or supply you with a car that works .

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