hi thanks for your reply ,car is exactly as delivered new, no aftermarket extras,dealer says he has checked for draw on battery while parked(he kept it connected to Multimeter last time for 10 days!) discharge rate is within normal range,he cant see any reason for it going flat,but admits that something is wrong.

i have even tried parking up with interior motion sensor disabled but still goes flat

parked in drive so can't leave on trickle but shouldn't have to with new car!!

Either it's a high parasitic draw, in which case a process of elimination should find the faulty component, or your battery is not charging fully, possibly a high resistance somewhere in the charging circuit - which might not show up on your dash lights. Got a feeling the MX5 battery is quite small for weight-saving, which won't help, though there is definitely an underlying problem.

Dealer job if it's a new car though.

Well, it's likely to be one of three things.

1. Battery is faulty, but it can't be that because the dealer has replaced it.

2. Something is drawing a considerable current when the car is switched off and parked. This might not show up on a "multimeter test" because it might not be constant. Alternatively, something like the lamp in the boot or glovebox is staying on all the time, but this shouldn't be too difficult to find.

3. There is a fault with the charging circuit and the battery is only being partially charged. The main dealer should have the necessary equipment to check this.

Of course, it's always possible that it's two or three of the above.

Most definitely something not right here.Did dealer give you parasitic drain figures ,both expected and actual for your car?May be an idea to check the alternator with engine cold and not running,just put your hand on the body of the alternator to see if it is warm.Just a thought.hth

Hi, no lights fitted in sunvisors, no light fitted in my glove box,nothing seems to be on when i checked the car in the dark.

Have left the car in the drive with the alarm off to see if that helps if not maybe someone will hopefully nick it,that would solve everything! otherwise i am in the hands of the dealer

You can check that the battery is charging OK by connecting a voltmeter across it, should read about 14,4 volts with the engine running.

Hi 72 dudes,frustrating is not the word i would use !!

As mentioned in my original post....after starting from flat with booster..I. run car on Sunday, did about 40 miles total , stopped for fuel after about 5 miles , car stopped and started ok ,came home later that day -parked car in drive.

On Monday started car ok and took for a run about 8 miles or so and gave it some serious welly ! tried to start today(Wednesday) flat battery again.....(1) lights on dash lit up ok (2) click from starter (3) tried lights very dim (4)I noticed new symptom, gauge needles shot up then down again when i tried to turn engine over , Car normally parked outside on alarm,interior light in off position ,boot light in off position, dealer has checked for undue battery drain, they say all normal.

I have called out Mazda RAC man so i will get record of breakdown today . i have noticed two things when i looked this morning --- the braided strap from battery earth to engine (under black tape ) feels loose and wobbly will get RAC man to check this--- also last night i noticed when sitting in car with ignition and alarms off the little car with padlock symbol (alarm armed) was still flashing on dash ,surely this should not show when i am sat in unalarmed car?

PS will see what RAC man finds

Edited by dendave on 02/01/2013 at 10:14

I did have a Mazda MX5 doing the same thing in our workshop and seem to remeber the coil pack getting hot.

I cannot remember whether it was caused by a fuel injection relay not switching or it was an ECU fault but the ign coils were staying live with the ignition key removed !

I think we found it by the fact that the coil pack was warm afetr the car had been off all night. bnce we disconnected the battery to rig up an ameter the relay dropped out so there was no current draw by the coil so no fault found.

Hi will check my coils when i can locate them on the engine ,have looked up lots of pics looks like seperate coil for each cylinder,will get back to you

Hi Dendave

I had exactly the same problem on my Renault Clio, it was the electric PAS relay which kept on energising (which shouldn't have obviously after I locked the car) and unless the car was driven daily the battery could discharge after only 2 days in the end as the battery got weaker and weaker given the toll on it - Hope this helps rather than confuses

Edited by MondeoMonkeyMagic on 03/01/2013 at 21:30

Hi

have a similar problem on a new Mx- 5, i need to find out the name of the dealer that had autorisation from Mazda on the module to see waht steps he has taken to identify the module as the fault

Used car to go to Leeds, then did not use car for a week, went to it battery flat, this has happened twice now, after being left for a week, car is 3mths old

A bit of an obvious question, but why is the bluetooth module "live" or connected to the battery when the key is off and removed? Wired incorrectly from new? Or part of the wonderful web of overcomplicated gadgets that new cars come with, designed by computer geeks who seem to have very little connection to reality?

Hi, bit of each i think,I dont need or care whether bluetooth is fitted to my car.Dealer replaced it and all my starting probs have gone away at last.

I think the car was wired wrong to begin with,but this problem didn't show until i left the car parked over longer periods.When i first had the car, i used it every day,so did not notice it at first.Module was definitely duff,but i think problem was intermittent as dealer didn't find fault at first on"dark" test.

I'm just glad its sorted at last!

Mazda obviously hasn't made any improvements to this roadster since the original post because I have a 2013 Mazda Miata/MX-5model with the same problem. The car has now been towed to the dealer on five occasions. Even the tow truck drivers have got involved in the diagnosis, telling me to keep the keyfob 50 feet (I'm in the US ) away. Another told me that the car battery drains because if the car isn't locked it keeps seeking the keyfob. The dealer is baffled, techical experts have been called in, all with no results. I've had a Mazda MX-5 or a Mazda Miata in various countries since they started making them. I've never had a problem with any of them, other than a "check engine" light on an old model.

This forum has given me more guidance than anything so far and I'm taking all the comments to the dealer. Many thanks.

I bought a used 2015 Mk4 MX5 1.5 roadster in super condition and very low mileage about a year ago, I love it but found battery flat after leaving it switched off in garage for about 3 weeks when I couldn't drive anywhere due to Covid shielding. Used a CTEK charger to successfully rebuild the battery. Spoke to dealer, they said they have a similar problem with all their Mazdas and have to boost cars on display about every week. I measured the drain, nearly 1 amp with everything that could be off turned off! Battery was not new but if it can sustain 1 amp drain for up to 5 days and still start the car it is not faulty (as it lasted so long I guess the drain must have reduced after a while)! Tried removing various fuses but could not isolate the load so I fitted a simple isolation switch that I turn off if the car is to be sittng for more than a couple of days. A bit of a fiddle to open the bonnet and turn it on but no more flat battery!