Battery Caps

Had a problem with an 8D lead acid flooded battery. The top of the battery was constantly wet. The charging system checked out fine as did the alternator. Finally got a marine electrician on board and everything checked out perfectly. Final determination was 2 "defective" battery caps.

Did some research and came up with these https://www.flowsystemsusa.com/
After 2 weeks of cruising the battery is bone dry on top and have not had to add any water. I replaced the caps on 2X8D's. I did need to purchase the "adapters" in addition to the caps. More than pleased at this time as the wet battery top was driving me nuts.

I added my Water-Miser caps 6 years ago. It reduced my need to add water by approximately 1/2. I have been very satisfied with them.

What is the measured width of the openings your the caps go into? Is it just tube, or is it threaded?
The caps on the website seem to have some kind of thread, maybe it`s just a locking device.
I have one 8D with hard plastic yellow screw on caps, almost never needs top up. And one (a Century/Yuasa) with push on flexible (rubbery) caps which needs lots of topping up.
Any help much appreciated.

The usual hassle with water coming out the batt fill is some form of overcharging.

BruceK said:

What is the measured width of the openings your the caps go into? Is it just tube, or is it threaded?
The caps on the website seem to have some kind of thread, maybe it`s just a locking device.
I have one 8D with hard plastic yellow screw on caps, almost never needs top up. And one (a Century/Yuasa) with push on flexible (rubbery) caps which needs lots of topping up.
Any help much appreciated.

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I don't have the measurement but my GCs have a standard bayonet style caps that I replaced with the Water-Misers. My start battery with the snap-on caps is not compatible with the bayonet caps. Maybe that's where Howard's adapters come into play.

Hmason, can you tell us more about the adapters?

EDIT: Just found this info on the adapters. I might have to try some on my start battery! I have 6 caps sitting here unused waiting for those!!

https://www.flowsystemsusa.com/Battery_Vent_Cap_8D_4D_12V_Adapter.html

I got much, much better results from Hydro Caps than Water Misers (which I eventually junked).

caltexflanc said:

I got much, much better results from Hydro Caps than Water Misers (which I eventually junked).

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I like the idea, too, but they look HUGE!



I have limited space on top of the batteries. I selected the medium size Water-miser caps to just barely fit.

How tall are the Hydrocaps? I can't find the info on their website.

I ordered the Water Miser caps, with adapters, for one of my 8Ds. Freight makes it expensive, all up it`s around 1/3 of the cost of the 2yo battery, but the caps are transferable to the eventual replacement, which may be delayed too.

I got my adapters in the mail yesterday and brought them along on my week long trip with my nephew this week. I'll install them during my next battery check.

Thanks for the tip, Howard.