NB 2.5 Gel Battery choice


been having trouble with my battery, so have bought a new one.

Put my reg into eurocarparts and chose the budget one:

Lion Battery (063 Battery - 3 Year Guarantee)Product Code: 444770631

I'm now wondering if this would be suitable - it should be as the search brought it up, however it says that it has calcium technology and dont know what this means?
I thought MX-5's were suposed to use a Gel battery, is this true?

Ideally i'd like this one to be compatible as i can then put it in a go out and enjoy the sun.
Would rather not have to go back and swap it if I can avoid doing so.

Is anyone able to tell me if this would be ok to use?
Any help is greatly appreciated.
Car is a 2.5 NB 1.8 S-VT.

AFAIK most modern lead acid batteries are now ‘calcium’ technology.  They use lead-calcium (rather than lead-antimony, I think) in the plates to improve reliability and performance. They are not necessarily gel batteries though.  Gel batteries use a gel type electrolyte, not liquid, and are common in motorcycles - some bikes even locate the battery on its side.  I’m not aware that gel batteries are common in normal road cars.


That battery will not fit properly you want the lion 114 or the panasonic.

The Westco used to get a good name but lots of people have had failures.

remember to connect up the vent tubes to the new battery. If the tubes are not there Autolink has hem.

The OEM battery is a Panasonic - available from mx5parts or from your local dealer. I would NEVER buy anything else - they will last for at least twelve years, some members report longer.
The Panasonic battery is vented - if you check the location in the boot you will see the vent pipes. It is IMPORTANT to only fit a gel, vented battery, or fumes will eventually corrode the boot surround. There are incidents involving non vented batteries causing more than corrosion, as in one case in the States (reported by one member) not involving an MX5 BTW - where a mother and child were overcome by sulphuric fumes and crashed the car, resulting in death to both. Isolated incident, but it provokes thought.
Cost? Well they aren’t cheap, but length of service equals at least two lead acid batteries, which may be cheaper individually, but add up to more than. See http://www.mx5parts.co.uk/battery-genuine-mazda-panasonic-mk1-25-p-3756.html

Check with your Area A/C - if a discount has been arranged between the Area and a local Mazda dealer, then you may get a better price than MX5parts, but if no discount available, then buy from them. As you say you have already bought the other battery, if it’s definitely a gel type and does have vents, then I can only suggest you either return it - if refundable? - or fit it for now, (if it fits) and buy a Panasonic next time.

Thank you all fo the advice. I dont think I will use the one I have bought, will return that.
I will go with one from mx5-parts.

I hope that you won’t find this an ignorant comment, but I thought that one of the reasons for fitting the Panasonic battery was because, being of gel construction, it did not need the vent tubes!


The original type Panasonic still requires the vent tubes to be attached. It’s actually an AGM battery rather than a gel filled one.

I think this post went flatWink…about a month ago!


I assume from your comment that all boot fitted batteries need the vents fitted?

Mine is battery of unknown origin, which has no vents fitted but shows no sign of gassing or corrosion!

Best regards 





I’ve seen too many corroded boot areas due to wrong batteries and no vents to believe you will get away with it long term.


Mazda probably didn’t go to the expense of fitting the Panasonic and vents because they were short of something to do that day :slight_smile:

Venting is absolutely vital as is properly securing the battery.

Because of the extra g - force in the boot, far more than under the bonnet, the battery really needs to be held solidly in place.

This is particularly difficult where the battery used does not fit the accomodation properly as in the MK1.

MK2/MK2.5 probably easier to secure a non standard battery, hence the less frequent examples of boot corrosion caused by batteries in the later cars. 

Thanks I have now had the correct battery fitted and the vent pipes repaired. Apparently the battery only vents if the gasses produced exceed 2psi.
Thanks for all your help.

In ideal conditions a battery does not produce a meaningful volume of gas to vent. Overcharging, for whatever reason is the cause of the production and bubbling of gas. Lead acid batteries with the relatively new calcium technology produce less gas when overcharged.

In my opinion most corrosive damage caused by batteries to MK1/Eunos  MX5 boots is related to acid leakage from poorly mounted/vented lead acid batteries rather than as a result of gas.