Battery venting is it done?

[noswellplease]

I notice my Vetus battery says maintenance free but some boat publications advise checking electrolyte level and topping up if necessary, so what should be done? Also I have no path for gas from the battery to be taken away from the cabin so should I be looking to create a route to do this?
If it's not really a porblem then I'll gladly leave alone. Russ

 

[ex-Gladys]

It depends what type of "maintenance free" it is... AGM or gel will not need topping up and are what is known as VRLA (vapour regulated lead acid). These are "sealed" and even generate a slight positive pressure as I recall. If your battery is a "low maintenance" conventional lead acid, then it may allow gases to escape. The main gas is hydrogen, which is obviously explosive when mixed with air in sufficient quantities. These quantities will usually only exist when you have a charger banging current back into the battery. Whilst doing that I would ensure you have ventilation and don't have any sparks (on a car you'd connect the positive to the battery pole, and the negative to the engine). Obviously that depends on your layout. Gladys has bus bars about 8 feet from the batteries, so I tend to connect to them to charge.

 

[markdj]

All battery installations should have ventilation as it is unknown what battery type will be used. It should be enough to have fresh air available in the boxes, doesn't need to be forced air with a fan.

Unless the batteries can be mounted in any atitude, eg. AGM and GEL, then I would think that a grill fitting would be recommended to ventilate your batteries.

 

[DGuthrie]

This issue vexed me when I built a battery box in the man saloon next to the engine compartment. I put in a couple of those louvred vents, but the man who did the engine said that ventilation for batteries means thin hoses from the vents on the batteries themselves (like little hose pillars built into the plastic case) taken through to the open air outside the saloon. Somehow, I haven't managed to get that job done; can't think wy, but a friend who was a marine engineer tells me it's not worth bothering so long as there's plenty of air movement around the batteries. However, though I may be prepared to take the risk, maybe you'd be advised to check further, such as the RYA's or YBW's tech people.