It was pointed out to me when I bought my car that the previous owner had fitted a Bosch lead acid type battery. Thought nothing of it other than cover doesn’t fit flush. Anyway the battery clamp doesn’t fit as it’s taller than standard battery. Now I was going to look at modding the clamp and then of course I started researching and reading all these horror stories about non standard batteries. So am I right in assuming the ‘venting’ issue is to stop condensation on the battery? I have read many posts and see that almost everyone says to get the Panasonic battery. I don’t really want to junk the Bosch if possible so really I’d like to know if there is a way to use a ‘normal’ battery without any issue?
Any advice appreciated except ‘go and buy a Panasonic’ lol!
The vent is to ventilate gases from the battery - all batteries emit sulphuric gas especially when charging (from the alternator). A lead acid battery has no external vents, so any gas goes into the boot. The boot isn’t ventilated very well (unlike batteries located under the bonnet) and worse case, a lead acid battery can spill acid out onto the car, which then burns off the paint and starts chewing at the bodywork. Horrifying? You should see the pictures - - - .
There is a cure, though it’s not so much a cure as a prevention, you need some anti sulphuric paint and paint the battery enclosure - not the battery - so any spills or corrosive effects from gas emission is minimized. Frankly, you need a sealed gel battery, these are vented, and if you don’t want to fork out for a Panasonic then get a Westco from MX5 parts., though these are getting some criticsm from some members who have bought them, others are happy enough, you make your own choice. I know batteries aren’t cheap - the Westco is around £90 IIRC, the Panasonic from a dealer can cost around £150, but if you plead poverty, or find the right dealer. then you can negotiate a discount (being in the Club helps). - I got 15% discount from a local dealer recently. Battery gas can be explosive, and corrosive, so it’s time to give it some hard thought I reckon.
Batteries give off oxygen and hydrogen during charging which is highly explosive. Some batteries use a vent pipe to take the gas outside. Check your Bosch to see if it has vent pipe connectors and if it has refillable plugs or not.
If your battery is “sealed” type “maintenance free” with no fillers or vents it is designed to recombine the gases into water which is retained in the battery. It can do this up to a limit when it has a safety valve which will vent excess gas. It cannot be refilled so if it needs to do this the water is permanently lost and this is one reason this type should not be overcharged. I recently bought a Varta (Bosch) battery and it is this type so yours may be too.
So, if it has vents consider a plastic pipe to the outside. If no vents or fillers it should be ok. That just leaves making it fit and clamping it securely. Be especially careful that the Pos terminal cannot touch any Neg car metalwark!
Thanks for the replies guys. Some very good points there.
I checked it out, not sure why I thought it was a Bosch cause it’s actually a Halfords maintenance free Calcium battery and looks new. The owner told me as much when I bought it. It does appear to have a couple of vent holes on it but nothing connected. The previous owner has just put it on the original battery tray but because the battery is a little wide it is sitting on the edge of the tray, so it is just loose really with the original hinged retention clip resting on the top. So a bit of a pants job to be frank! Very good point about the positive terminal as the battery is essentially free to move. Fortunately it looks well insulated but you can’t take any chances. For the time being i’ve wedged it on all sides so it can’t move around but I’ll have to use a different base and then look at adapting the retaining clip so it clamps it firmly in place.
So my next question, is a calcium battery a problem potentially with the corrosion issue or will it be ok?
I recall having to help out one owner who had brought a Roadster from an import specialist; the “specialist” had used nylon ties to hold the battery in place, with the inevitable mess resulting, when the battery shifted, split a cell, resulting in a wrecked boot carpet and the need to repaint the entire boot.
Calcium batteries still vent off, but like so-called sealed batteries, less than a conventional top-up battery. Halfords likes them because they can keep them on the shelf for longer. They can’t be charged from flat though, and seem to have a shorter shelf life. The Panasonic battery though has a proven very long service life, if properly looked after; I had one that was 14 years old, and still working fine. £90-100 seems a lot for a battery, but then, a thoroughly conventional Bosch battery for my Alfa diesel cost me the thick end of £150. Batteries are just more expensive these days.
The other recommended replacement battery is the US-made Westco from MX5parts.
Calcium batteries are usually the “maintenance-free” type as that technology causes less gassing so they can be made with non removable filler plugs. Check yours or check with Halfords.
All batteries inc Gel, AGM and Maitenance-free types have vents, it’s just that rather than the old tech wet batteries which had open vents and used to use quite a lot of water (by electrolysis during charging, converting it to oxygen and hydrogen) these only vent if gassing is excessive. They are designed not to gas too much as the water cannot be replaced. Old tech wet plates will usually have an obvious pipe/nipple for a vent tube to be attached.
Therefore there should be no corrosion issue so long as it doesn’t leak acid from breakage and other cars also have batts in the boot.
Halfords batteries geerally have vent pipes on either side. Problem is that they are holes so you need a suitable fitting to convert from that to the pipe in the MX5. I haven’t solved that one yet as I only fitted my Halfords battery last week but I’m thinking a couple of 90degree adapters for washer tubing look about the right size.
In my MkI I found that the large corner bracket just moved backwards to a second set of threaded holes already in the boot floor. The clamp that went over the top of the Panasonic battery was OK for height as there were a couple of different holes in the body for it to hook into but unfortunately it was a fraction narrow. So I’ve added a bit more metal to make it reach. The interior trim panel had a dotted line on the back that showed where to cut it and it moved back again to an existing second set of press-studs on the boot floor carpet.
As for the Westco battery - the Halfords one cost me £44 and comes with a longer guarantee. I might have to buy a pair of plastic elbows but it’s still a bit of a no-brainer.
I have just had to replace my battery as it kept letting me down. I read all the posts on which battery was best and eventually bit the bullet. I took a short drive to my local Mazda dealer and purchased a new Panasonic battery, not cheap but if it lasts 14 years like the old one did, I don’t have a problem with the cost.
Although I won’t be going to the pub for a couple of weeks.
