Question for MaineSail re: AGM batteries

[Ivan]

I just read your great article on "battery orientation" on your site. Very informative. However, at the end you quoted an ABYC specification that has an end note that applies to ALL batteries, not just flooded ones. It raised a question, and I hope that you can amplify a bit.

The ABYC spec was:

10.7.9

A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery.

10.7.10
Battery boxes, whose cover forms a pocket over the battery, shall be vented at the uppermost portion of the cover.

NOTE to 10.7.9 and 10.7.10: These requirements also apply to installations of all batteries whether they employ removable vent caps, non-removable caps, are “sealed” or “maintenance free” batteries, or have pressure regulated valve vent systems with immobilized electrolyte (gel and AGM batteries).

Now my question is: With AGM batteries, what conditions are likely to release hydrogen gas, and how much gas would be released compared to a flooded battery subjected to the same condition?

Thanks

Ivan

 

[Maine Sail]

I just read your great article on "battery orientation" on your site. Very informative. However, at the end you quoted an ABYC specification that has an end note that applies to ALL batteries, not just flooded ones. It raised a question, and I hope that you can amplify a bit.

The ABYC spec was:

10.7.9

A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery.

10.7.10
Battery boxes, whose cover forms a pocket over the battery, shall be vented at the uppermost portion of the cover.

NOTE to 10.7.9 and 10.7.10: These requirements also apply to installations of all batteries whether they employ removable vent caps, non-removable caps, are “sealed” or “maintenance free” batteries, or have pressure regulated valve vent systems with immobilized electrolyte (gel and AGM batteries).

Now my question is: With AGM batteries, what conditions are likely to release hydrogen gas, and how much gas would be released compared to a flooded battery subjected to the same condition?

Thanks

Ivan

Ivan,

Over charging GEL or AGM batteries will release gas. This is why the ABYC does not make any exceptions for "venting". With AGM you are not "required" to have acid containment but you still need to provide for venting.