Were the previous batteries really failed? Or were they replaced to restore iStop? If it was the latter, it was unnecessary. The act of disconnection restores iStop, so it always seems the battery change has worked!
I think the problem with the ND2 battery is that when completely discharged the ‘normal home chargers’ will not work. The internal construction is such that continuous very high amperage and voltage is required to get the electrolyte stimulated enough to facilitate recharging.
All Mazda main dealers have the equipment to correctly recharge a ‘good’ but ‘flat’ ND2 battery so you would hope that the OP did not get duped into buying new batteries!!
Somewhere on here is a link that shows the construction of these batteries. From memory the plates are very very close together which is why they require ‘special’ charging routines that are not normally available on the ‘cheaper/home’ chargers. The ones that you can control fixed voltage, amperage and times are usually quite expensive.
I use it The C-TEK MS5 on my ND every Winter. Keep it on when the ND isn’t used.
Twice when the battery seemed as dead as a doornail, it revived it and I still have that battery in the car.
I find that if I mostly close the bonnet-ie catch not fully engaged, and put the C-Tek cable down near the light it’s fine and the cable is not squashed.
Lots of choice and good advice above - just saying the C-TEK worked for me for 7 years now,
To Clarify: The battery was only flat because I failed to connect the c-Tek, before a cold spell and not using car for 3 weeks!
Hi,
Re the two ND batteries that failed these were the circumstances-
-
The car was purchased new on an 65 plate and had done 36k miles over four years to the time of failure. It was kept outside on a driveway in all weathers. The battery failed on the driveway. My local independent garage came and took the battery and had it for three days trying to revive it using their “special” battery restoration equipment/charger but weren’t able to bring it back to life so I bought a new battery from Halfords which they fitted for me and they only charged me £20 for fitting which included coming to collect the dead battery.
-
The car was purchased used from a main dealer on a 19 plate with 3500 miles on the clock. The battery had failed when I went to pick up the car and they replaced it with a brand new Mazda recommended battery. This battery failed in an airport car park after two years. The drive to the airport was 150 miles so it should have been fully charged when parked up. On return 18 days later the battery was dead, it was November. I called out the AA who tried to get the thing to charge but couldn’t. They got the car started by jumping it. The AA chap said he had done quite a few mx5 batteries. I drove home (150 miles) and parked on the driveway. The next morning the battery was flat again. Mazda came and recovered the car and eventually replaced the battery at my cost.
My first MX5 was an NC which I owned for 6 years and did 48k miles in. It was parked on the same driveway as the first ND above in all weathers and never had any issues apart from front break pads needing replacement (my driving 
).
So, my reason for buying the charger is one of economy, reliability and my uncertainty about the battery life. I just want to know that the car is available when I need it.
After connecting the charger up yesterday it took from 5pm to 9.30 this morning to get the battery back up to full charge. I’ve no idea what this passage of time means but at least I know it’s fully charged 
.
Thanks to everyone who chipped in with help and advice.
Regards
Clive
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I recommend buying a lithium emergency starting battery.
If your battery should fail somewhere awkward, it will get the car started and get you home.
I got a Halfords one for a 3 litre car as I also have a 320d.
They are made by Ring but the Halfords version is cheaper for the same thing. The huge AGM battery in the BM did fail and the little lithium batterystarted the car with seemingly no effort.
It sounds as if there is dark current when the car is switched off. Try an ammeter between the neg lead and terminal. DO NOT try to crank the engine with the ammeter in place, unless you like sparks and molten metal.
I’m not sure I understand this? I’m a numpty with electrical stuff. I do have an ammeter which I use for measuring dc voltage.
What setting do I use on the ammeter?
What lead and what terminal am I measuring between?
Thanks in advance
Clive
Thank you, I’ll investigate that
Many thanks
You’re looking for something probably less than 100 mA. Turn everything off, remove the key and open the bonnet. Ensure all other doors are shut. Disconnect the negative battery lead and put the ammeter between the lead and the neg terminal. Any current is draining the battery but a really, really small one might just be the clock or immobiliser.
If there is any significant current, you may be able to identify the culprit by pulling fuses or connectors.
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Hi all, so a further question.
My car is now on charge using the CTEK charger and all seems fine.
It has reached the green battery stage 7, described in the instructions as “Float”. IE fully charged. The instructions say that it will stay in this condition for 10 days and then switch to stage 8 “Pulse”
Unfortunately I need to get the current mileage from the car. To do this I would normally just push the start button twice without depressing the clutch (so no engine start) to get the reading.
My question is will it be ok to do this with the charger still connected?
I appreciate I could disconnect the charger but would prefer to leave it doing its thing.
Thanks in advance
Clive
Imho, should do no harm.
Yes.
Don’t do it. It may cause all pet hamsters, gerbils and guinea pigs within a 5 mile radius to spontaneously combust. It will also cause the earth to stop spinning on its axis…and a rather attractive lady dressed in white (not Ginger Spice) driving a Lamborghini Countach will have to save us.***
Actually, as everybody else has said, it will not cause any harm.
***For those of you too young to remember, it was a Pirelli Tyres advert from over 30 years ago.
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Thank for your replies, particularly enjoyed the humour 
This ^ If there’s any doubt on modes, using the first ‘normal’ mode will just mean it ‘may’ a bit longer to charge, depending on what the mystery ND2 battery is. I think a poster in the past asked Ctek and i think that’s the gist of the reply they gave. Also, I’ve read Cteks can play up and ‘get stuck in a mode’ of you fiddle around pressing that mode button too much.
It’s probably charged by now, even in normal mode 
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Oh, I didn’t see the prior post date 
I have a solar panel that I clip to the battery. It only puts out a very small current and would probably take a month to charge a flat battery but it keeps the battery topped up without any risk of overcharging and all for free.
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Where did you get the solar panel charger from?