Need New Battery?

Hi Paul…Our first car a 2000 1.8 had the original Panasonic battery. It got very sluggish after weeks of hibernation one winter. I did not start it up as we are new to the game and had never had any trouble with previous makes of cars. I then bought an intelligent CTEK MXS3600 charger which can be permanently connected via socketed leads from the battery when the car is not in use. It is supposed to revive a dead or dying battery. Now, after 11 years, the car it is still working vigorously with the new owner and the orignal battery. I wrote a short light hearted article for STHT- April 2010 - detailing the saga Have you any contacts with a CTEK charger or equivalent to try it out and possible save your battery and some money? Cheers

Would like to thank everyone for there kind replies. It looks like a charger is what I need to try 1st, the mentioned chargers CTEK & Optimate seem to have good reviews, can you connect these to the battery in the car without removing the cables to the terminals.


Thanks Everyone



 Yes they both come with crocodile clips , and a permanent lead you can attatch to the terminals and run into the car so connection is a 2 second job !

Much appreiated Big Smile

 Hi Paul,

I also had to replace the battery a few months ago. It had an ill-fitting standard wet acid battery with no venting and I was lucky that the floor pan hadn’t been too badly damaged. I went for the Wesco unit from MX5 Parts and and Optimate 4 charger that I bought from Amazon for a few quid less than the MX5 Parts price. I’d highly recommend the Optimate - I’ve attached the in situ connector to the battery terminals so it’s now dead easy to just plug in the charger. The Optimate is a charger and conditioner with a microprocessor controlling the charging/checking cycles, so you could leave it connected indefinitely if, for instance, you laid up the car over winter. It takes longer to charge a low battery than a conventional booster charger, but as has been said already, you must only trickle charge gel or AGM batteries anyway. If you use an intelligent charger a gel or AGM battery should last at least as long as a wet acid unit.

Many thanks DaveP2629, really appreciate the info.





 HI Dave,have a look at the solar trickle charger. I have mine stuck on the garage window ,the other end fits into the ciggy lighter in the mx5. However the optimate is the biz.


Because you already have a solar trickle charger I’m sure that will do what you require without harming a gel or AGM battery. If you’re thinking of buying the WestCo battery, that is an AGM (Absorbed Glass Matt) unit and my usage instructions supplied by MX5 Parts say: "Never use a boost or ‘electronic’ charger. Only ever use an old fashioned 2-3 amp Trickle Charger, or a charger specifically designed to work with ‘Gel’ or ‘Glass Matt’ batteries.’

These gel and AGM batteries discharge and charge up very differently from the wet acid type. When they discharge the charge goes from the centre of the battery and works its way out, conversely, when you charge it up the charge starts at the outside and works its way in. That’s why the charging has to gradually move in through already fully charges material and too much power will damage that fully charged material. If you completely discharge one of these batteries it will take from 3 to 7 days to recharge it! Moral is, keep it charged up and if you’re not using the car regularly then trickle charge it regularly.

Yes, the Optimate is an excellent product - but if you have a good trickle charger you don’t actually need to buy an Optimate or an equivalent from another maker.

Hope that helps.


I have been through this battery issue and done some tests and have these observations.

It’ll cost you some money but before you go and buy a new battery buy a CTEK3600 charger (I prefer this over the Optimate as it will also charge at a 3.6 amp rate for other standard batteries you may have on other cars, where the optimate will not).  It is preferable to remove the battery from the car to charge but you can do it connected.  But remember the dark current drain on the car with nothing switched on will be 20mA so this can affect your readings.  I would check this is no more than 20mA firstly on the 10A scale on a meter then if nothing switch down to 200mA scale and check for the 20mA. Connect the meter between the -ve battery terminal and the corresponding lead which is disconnected, the +ve should be connected.  Anything significantly more than 20mA then you have a fault on the car somewhere which drags down the battery and should be investigated.

Connect the CTEK and charge the battery on the motorcycle 0.8A setting.  If the battery is flat it will take up to 72 hours.  The CTEK will indicate when the charging is complete by it’s LEDs and will remain steady on green if the battery is good.  If it cycles between red and green at less than 3 minute intervals then the battery is suspicious.  At that point remove the battery and check the voltage with a digital multimeter across the +ve and -ve.  It should be around 12.7v.  Check the next day.  If it is still 12.7v then check the next day.  If it is still 12.7v you can be fairly certain that the battery is OK and put it back on the car.  However if the voltage starts falling over two days (say 12.5 by the second day, then to 12.2 or less over a week) you can be sure that the battery has had it. 

If you have to have a new battery, my recommedation would be to buy a new Mazda (Panasonic), part No  B61R 18 520C.  They are a bit expensive and only available from Mazda dealers but as a club member I got 15% off making the price £114 inc 20% VAT.  It will last longer if you look after it, you will have no fitting problems and you won’t have to worry about your boot rusting.  Even the Westco will cost £90+ inc PP and there is some doubt over it longtevity.  Also does it fit properly without messing about?  To me, the extra £25 is worth it for no hassle.

Use the CTEK permanently connected on the low charge rate to keep the battery up and in good condition if you use the car less than weekly. The worst thing that can happen to these batteries is to be continuosly cycled fully discharged/charged.  They can also eject the fibre mat from the vent holes or even explode if they are subjected to a high current charge.  Never use a booster or charge at more than 4 amps (and I believe even 4 amps may be too high).  Never use a continuous charger that doesn’t switch of when the battery is fully charged.  The beauty of the CTEK and Optimate chargers is that they monitor the battery, will not overcharge and will only give a pulse charge when the voltage drops thus keeping a constant state of charge which is what they like.

went for the CTEK charger, hoping it arrives tomorrow, just wanted to say many thanks to all who took the time to answer me post, really appreciate it, I will let you konw how I get on.





Phil, if you don’t mind I’ll stickey this and make your post into an FAQ at some time, it’s one of the best battery posts that I have seen

 The copy Ctek chargers won’t charge a totally flat battery, they trickle and cycle only.

Shock So I might have just wasted my money, I have just put the battery on charge this morning.


 Hi Paul,

Marpar probably knows the Ctek better than I do, so he may well be correct. I would have thought though that it should charge up a flat battery, just like the Optimate would, but it will take a heck of a long time - maybe a week or so. I use the Optimate to charge up wet acid batteries on our other cars too. My Saab 95 Aero had a low charge around Xmas time and 24 hours on the Optimate fully charged it again - and that is a beefy 74Ah Varta. Fingers crossed for you.

 Does anyone have the specs of what a westco type battery should be reading?

Im still having concerns with mine its about 3 years old and has been charged with an optimate 4 charger , lately its been stored in a lockup with no power and only seams to last a week or so then wont start, battery terminals are good clean and tight all earths are clean including new engine earth, no alarm is fitted just an MX5 parts clock and cubby hole . nothing else is permanently live.

Readings Im getting today are :

battery voltage 12.74v at standstill, when engine running 14.3v so I take it the alternator is charging ok ?

car is used weekly but often very slow to start today I rolled it back and bumped it out of the garage . When the car has been used lately it has been on road rallies at night so lights on,  maplights on but not stopping the engine for a couple of hours  etc

Could it be the clock? if I disconnect the live feed and put a multimeter in line to it what sort of amperage should I see if its ok? would a digital clock use less amps than my manual one if so any suggestions for what fits (does the Mk2 have a digital clock?) I would want it to be lit up at night for rally use ?

Also (and it might be a clue ) the clock backlight has blown and appears to be all in one with the wires (not a removeable bulb ) any idea where I might get a replacement , Ive tried MX5 parts and they are looking into it ?

Finally has anyone fitted a cut off on the battery and would this help if so was it simple and where did you put it ? I was thinking of putting it behind the drivers seat but it could go in the boot?






the Halfords trickle chargers are like this and the automatic range too , apparently according to the buyer at the head office its a safety feature as it wont dispense a charge until it gets over a certain voltage back (think it was 7volts ) so it wont charge a fully flat battery  . So I bought an Optimate 4 and that will charge a fully flat battery over 36 hours or so, and so does the Cetek one I got free with my practical classics subscription ( best deal ever !)

Sorry have just re-read marpar’s post, hope he means the Lidl copy chargers?




Great news, checked on the progress of the charging and it’s fully charged and the car startedSmile, many thanks to all your help.



I’m sure he does mean the COPIED  CTEKs like Lidl’s.  A real CTEK has a De-sulfication phase for a flat battery and will charge it OK providing the battery is good.

Yes it is the Lidl copy.UltimateSpeed,ULG3.8 A1. After ringing the help line and reading the handbook, it has to have at least7.5v. to work. It has several modes and safety features, it is also suitable for Absorbent Glass Mat batteries.The charger can be set to 0.8A or 3.8a, when fully charged it switches to maintenance charging mode.