Due to a lack of use, my 2002 1.8 MX5 battery lost its charge. I read on a forum that I could charge the original gel battery with an old fashioned trickle charger. After an overnight charge I noticed that the battery had become warm to touch, which worried me a bit. I used a multimeter to check the charge of just 6v, but it wasn’t enough to start my car. I decided to get a jump start and give the car a run for about 8 miles. To my horror, the batery had become so hot that it started to vent gas through the vent system. The battery was really hot to touch so I stood it in a bowl of cold water to cool it down. Once cool, I trickle charged the battery for a further 10hrs or so, and it reached a voltage output of over 12v. The battery is back in the car, and after sitting all night it has just fired up without a problem. My concerns are whether it might get really hot again if I go on a run, and why it got hot in the first place. I’ve never had any problems with the battery before, which is now the grand old age of 10yrs. I am a very low milage driver and the battery has never really had long runs to keep it well charge, and yet the battery hasn’t faultered before now, which suggests what a brilliant little battery the Panasonic slim gel battery is. I would be really greatful to hear from anyone who has had a similar experience, or can offer me advice on my best way forward.
I’m not an expert, but you could place the battery in a bucket of water while charging (water level not too close to the top of the battery of course!) to keep it from overheating.
If you are into winter driving - then getting a new Mazda battery is only the cost of two tanks of fuel, which for another ten years use seems worth doing.
My local Mazda dealer (near Horsham) offers discounts on batteries - so worth asking yours.
Thanks for the comment.
Just to keep you up with developments, I’ve just covered the same 8 or so mile trip that caused my battery to boil. The battery remained cool and did its job.
I would have thought that it would be damaged to some extent after such an event, which surely must be the case. Next time I trickle-charge my battery I’ll try the water trick to keep it cool, that is unless I take the plunge and splash out for a CTEK or similar charger.
I’ll probably not fully trust my battery until its proves itself over the next couple of weeks.
Has anyone else had a similar experience?
my olny guess would be that the baterry water level was low…have you checked it or is it a sealed one?
The battery is a sealed gel type, so it is maintenance free. I now know that you can’t charge it in the usual lead acid way. Rather, it requires a slow charge over 72hrs or so, preferably with a Ctek or similar high tech charger, or alternatively an old fashioned low amp trickle charger. A booster or electronic charger will apparently damage it. By the way, I’m no mind of knowledge on the subject, it’s only what I’ve picked up in conversations like this.
If you had it on charge overnight (what sort of current?) and it only reached 6 volts then I suspect it had a number of shorted cells. That could explain why it got so very hot when you ran it in the car and the alternator tried to shove enough current in to raise it to 14 volts or so. Maybe that current burnt out whatever was shorting the cells so the battery’s working again.
If it was me I’d be slightly worried that whatever went wrong might happen again and that the battery’s cells may now have a very unbalanced state of charge so the capacity’s probably well down. At 10 years old, I’d think it’s time to retire the old battery gracefully and maybe invest in a battery conditioner to keep the new one in good nick between uses.
I really wouldn’t recommend standing the battery in water!
I suspect that your charger is at fault here. Are you really sure it is a trickle charger? The symptoms you describe are what I would expect when you try and charge a Panasonic with an ordinary charger .
Gra
Absolutely!! One of the fundamentals in electrics is the water and electricity don’t get on too well
If the Gel battery is venting off gases when charging? and becoming as hot as you say? and cooked it, ,then the charger is to powerfull for that type of battery and by the sounds of it ,you have now killed it, you need to get a new battery buddy.
M-m
After a couple of days in the car, the battery seems to have made a miraculous recovery, hence my reluctance to give up on it just yet. It begs the question how this can be so after such an episode. It all very odd and yet someone out there has the answer!
Comments appreciated.
I can’t really say what went wrong with your battery but I do think you should consider replacing it, partly for safety’s sake but also because 10 years is a good innings for any battery, winter is tough on batteries and you don’t want to get stranded.
Hi Geoff -I think the issue is they get on too well … i would be concerned with a battery over heating this way -my thoughts would to buy a new one …
I read about using a bucket of water (to about 2/3rds the height of the battery) on another MX5 site. I’ve used it once without any problems but clearly one has to use common sense.
Just as a point of interest, the Mazda manual states that the Panasonic battery may be charged at a rate of 20 amps for 30 minutes providing it is placed in a pan of water to reach half way up the side of the battery! I would think it may well not do the battery a great deal of good, but, it is in the manual.
Regards Geoff Peace.
It seems to me that if you need to cool a battery during charging, then you are charging at too high a rate. Interestingly, in the Rod Grainger books some of the wording regarding battery charging seems to have come straight out of the Mazda manual, however this business of standing the battery in water doesn’t appear in the 1.6 book but does in the 1.8 book
I agree, charging to fast will kill the battery any way, and booster/fast charging is a big killer, and I also agree with the water bit, I have never had to stand a battery in all my years in water, even from the good old days also with good old wet cells with the tops popped off for venting while they are on charge with the correct charger and rate, and the need to top them up with acid or deionised water, when they did not have view windows of different colours and maintenance free.
M-m
You are correct, an old trickle charger will damage it. They need to be managed when being charged.
Buy a good battery conditioner like Accumate and it will cycle, de-sulphate and recover batteries as well.
I (and others I know) have used these for years - great product in my view.
I have to say, regardless of what the manual says, I don’t like the idea of standing the battery in water while you charge it. Call me old fashioned if you want…
I would have your regulator checked, use a multimeter or if you are not an electrical whizz, get an auto electrician to test it for you.