help! Battery/Charging Issue


Asked by Dec 12, 2014 at 02:56 PM about the 2012 Mazda MX-5 Miata Grand Touring Convertible w/ Retractable Hardtop

Question type: Maintenance & Repair

This has been a chronic problem with my miata.  I have a 2012 hardtop.  If I don't drive
the car for about a week, the battery dies.  I've been towed twice into the dealer, and
each time had the charging system checked.  Each time they said that they could see
nothing draining the battery at all.  They suggested I buy a battery tender for when then
car is idle, which I did.  Especially makes sense for the winter months.  Its a constant
battle to get the dealer to go any further.

Finally I thought I just might have a bad battery.  I went out and bought a highly rated
aftermarket battery, and sure enough when I had to park the car outside my garage for
a week.  It died too.  Do you have any suggestions?

4 Answers


I had the 2011 MX-5 Hardtop (which I traded about 2 months ago)...The only battery issue I had was during the winter when I parked it for over a week and driving my SUV instead. The OEM battery drained and had to have AAA replace it. Negligence on my part, since there are still things that draw from the battery even when the car is off....Out of curiosity, I looked to see what others had to say about this...One reason in your case (and also mine) was that the key knob may not have been turned all of the way to the "off" position (which is at a odd angle) from the "acc" position. The MX-5 definitely needs push button start..hopefully, the next gen car will finally have it!

1 out of 1 people think this is helpful.

interesting... I'm taking it to a mechanic outside the dealer to investigate. Let's see what he says. Thanks !

1 out of 1 people think this is helpful.

No problem, minkmanVa! I owned my 2011 MX-5 PRHT for 2 years without ANY chronic problems at all. IMHO, it's a well-built & very reliable car. I'd be curious to hear what someone (besides the Mazda mechanic) has to say after giving it a look! :::Still miss my MX-5..hope she finds a new & caring owner soon (she's still at the Dealer's lot waiting for a buyer):::

1 out of 1 people think this is helpful.

Okay I've read many posts from owner who have a phantom draw on their battery. The problem I'm addressing is for the cars where the room fuze draws close to 1amp it should only be about a tenth of that value. Your problem is a bad ecu. Something fails and shorts inside the ecu initially you find a blown 10amp room fuse you replace the fuse and it then starts this excessive draw. A small current should be expected as it maintains error codes. A new ecu solved my problem sorry for the bad news.

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