Why are battery filler caps hidden?

[Tony Brooks]

Most if not all VRLA's recombined H & O2. That is why they are also known as requested omination cells.

 

If you open one up, the gaps between the plates are filled with cloth like fibres, to absorb any liquid.

But those are more likely to be designated Absorbed Glass Mat - AGM.

 

I believe that you can get VRLAs using flooded cells.

[Guest]

Maintainance free wet batteries are called VRLA (valve regulated lead acid ) batteries.

When a normal battery fizzes the gas escapes and eventually the lost content has to be replaced with purified water (I'm not up for arguing what is best). A VRLA however has a casing designed to withstand an amount of fizz up until the safety limit of the regulated valve. Under normal use this should very rarely happen and therefore the battery should be maintenance free.

I once had a set exactly as you describe (Yuasa VRLA) Best batteries I ever had, bought secondhand and lasted a long time.

The ones I currently have with "hidden" caps are not of this kind. They come with vent pipes fitted to release gas pressure. They are "normal" batteries, with a sticker over the filler caps, almsot identical to my last set (except no sticker on those.)

[Guest]

And as an afterthought for a second greenie.....

 

Since a charged/fizzy VRLA is under pressure you would have to be a splatter faced numpty to undo the filler cap to see what was happening (might be last thing you did see).

 

Message ends.

My one time Yuasa VRLA had no caps fitted for the very reason that you state. My latest batteries are "normal" batteries with vent pipes but stickers over the filler caps.

[cuthound]

But those are more likely to be designated Absorbed Glass Mat - AGM.

 

I believe that you can get VRLAs using flooded cells.

I have never seen a flooded VRSLA, only recombinant or Usually gel types.

 

The original VRLA's were developed in the 70's for the telecommunications industry and came into common usage from about 1980. It is a fairly recent thing to call them AGM's, and in AGM's they generally use a woven glass fibre mat, rather than densly packed loose strands to hold any electrolyte which may be temporarily in the liquid state.

 

Edited for spillung.

Edited August 21, 2016 by cuthound