Leisure battery problem - pls help

[Deleted member 5467]

Currently in Spain and just found our towels had rot spots on them. On looking into this we found the screws attached to the strap which hold the battery in place were covered in white fur (acid???). This is a self build very carefully done with a sealed gel battery. As far as we can see the battery isn’t leaking. The screws are holding the battery in place with a nylon strap screwed into fabric covered wood plinths. We have stupidly only taken the photo after cleaning off the white foam. Clearly not putting any towels next to it now. Anyone with professional knowledge who can tell us what happened, what we did wrong and what we need to do now would be appreciated have induced screws in question

 

[Pudsey Bear]

I'd hazard a guess at it being nothing to do with the battery, but the zinc coating on the screws reacting to the towels may be slightly damp.

 

[Deleted member 5467]

Thanks but towels were dry & sitting in a shallow plastic tray which was unaffected, not sure if they slipped into screw but if they did they were dry.

 

[Deleted member 5467]

Actually smelt of metal when we cleaned it off too

 

[saxonborg]

Appreciate you say sealed battery but my sealed batteries are vented to the exterior, do yours have external vents?

 

[Pudsey Bear]

I meant the screws, (brain fart) as they are cold they could attract moisture from the air around them.

 

[Molly 3]

Perhaps change the screws and washers for stainless??

 

[TJBi]

Are the screws and washers both made of the same material?

 

[Deleted member 5467]

The screws are zinc and there are no vents as far as we remember on battery. Oddly this was installed two years ago with no issues until now or at least we don’t think so. Regards moisture on the screws I doubt that it’s been 32 degrees here dropping to 27 today LOL.
We are thinking stainless steel like you good people say, just would like to know a definite cause, especially as we don’t want this to happen again and especially when in foreign lands.

 

[Pudsey Bear]

A plastic shield will stop contact at least

 

[Deleted member 11]

Dissimilar metals I would say (screws, washers and base)

 

[Ardachaidh]

It's a "white rust", corrosion of the zinc plating. (information here: http://www.the-cfa.co.uk/media/42769/gnfixings_corrosion.pdf)

Stainless steel is the answer.

 

[trevskoda]

The zink is in fact an anode wherein contact or close to other metals further up the galvanic table will dissolve and leave a whitish powder, many i have changed both at my old job and now with boat engines.