Do AGM batteries need to be in boxes?

[CF32907]

Originally Posted by crayiii

I currently have two AGM 8d batteries in the engines compartment. Both are in covered battery boxes. We need to add capacity but are in the Caribbean and can't find any battery boxes except group 31.

If I add batteries, it will mean I can't have them in battery boxes. Is this okay?

You have many people giving you feedback that do not know the facts or requirements and really need to review them before posting.
Number one, the USCG is the only one that puts out requirements / Regulations. They do not require battery boxes at all, AGM or flooded batteries. Batteries must be secured so movement is restricted to no more than an inch in any direction. They also must have a rubber boot / cover protecting the positive terminal. That is the only regulation for battery installation that is required.
ABYC (American Boat and Yacht Council) puts out all guide lines for boat and yacht construction. They mirror the Coast Guard battery requirements.
I've built many boats, have surveyed thousands. Personally I would always have my boats with secured battery boxes. If I inspected one with secured but open batteries, I would recommend boxing but I would not make it a mandatory change. If I did that and it not being a Regulation, the deal go south because of what I said, I could be taken to court by the seller as well as a broker. Can only report fact of reg's, and battery boxes are not required.
Surveying for over 20 years, never seen a split battery. Although I seen much damage from improperly vented batteries, gas and fuel lines over the tops of batteries, strapping that was totally lacking for battery security. Virtually evey sail boat with batteries under the nav seat / quarter berth never have proper ventilation.
Capt. Vince Rakstis, Ret.
PS: Before sending me nastygrams, look up the USCG Regs.

[YANDINA]

A battery box with a correctly fitting lid provides a level of protection from additional hazards if the boat is sinking and you NEED 12 volts available. A correctly fitting cover creates a bubble of air to keep salt water off the exposed terminals.

Unfortunately I frequently see holes drilled in covers to accommodate wire entry that defeats this protection - you will see that battery covers have downward pointing extensions to allow cables to enter from below and maintain the air seal.

True it is of secondary concern but worth doing if not too inconvenient.

[CharlieJ]

@Yandina
Your advice is contrary to good engineering practice and does not comply with the voluntary ABYC Standard E-10 Storage Batteriess:

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

All lead acid batteries will vent hydrogen gas as part of the normal charging process; some more than others. The vent in the battery box cover is to ensure that this highly explosive gas does not accumulate in the pocket formed by the cover.

[YANDINA]

LOL the amount of hydrogen you could trap in a battery cover wouldn't even float a balloon.

[CharlieJ]

And yet those are the Standards that the surveyor will be inspecting to and that is also the reason that battery box manufacturers put vents in the box tops.

And by the way, the amount of hydrogen that would fill a ballon would make a very disturbing explosion.

[CassidyNZ]

Originally Posted by YANDINA

LOL the amount of hydrogen you could trap in a battery cover wouldn't even float a balloon.

We had battery problems on a voyage with an alternator that was unregulated and charging at north of 17v. In this environment we connected a spare battery (from the anchor winch) with jumper cables in an attempt to charge it for a short while. A crew member went to disconnect the cables to avoid damage to the battery.

It didn’t avoid damage - there was a spark at disconnection and the battery exploded covering the whole engine room and the crewmen in battery acid. All that was left of the battery was the six sets of plates standing on the plastic box floor.

Never under-estimate the threat of the hydrogen that is generated.

On topic, a New Zealand registered boat applying for CAT1, all batteries need to be in boxes. I’m not aware of any exceptions to this requirement for AGM, gel or even lithium batteries. I quote:

20.04 All batteries must be installed securely in adequate battery boxes. The bottom of the box must be above the level of the cabin sole. Battery boxes must be acid proof unless all the batteries are fully sealed units

While it isn’t obvious in the regulations, no CAT1 inspector that I know will issue a certification unless the boxes are lockable. The requirement is vested in the word “securely”. I’m sure there will be posts that prove me wrong . . .

[john61ct]

Originally Posted by CassidyNZ

A crew member went to disconnect the cables to avoid damage to the battery.

It didn’t avoid damage - there was a spark at disconnection and the battery exploded covering the whole engine room and the crewmen in battery acid

Was this an AGM bank?

For FLA I've never advocated sealing the battery box for normal usage.

But when it **is** sealed, then IMO a venting method is required.

I've never designed for the goal of continuing to discharge while submerged, that seems a challenging use case. . .

[CassidyNZ]

Originally Posted by john61ct

Was this an AGM bank?

For FLA I've never advocated sealing the battery box for normal usage.

But when it **is** sealed, then IMO a venting method is required.

I've never designed for the goal of continuing to discharge while submerged, that seems a challenging use case. . .

No, FLA bank. 6 Trojan T105 in the bank but the battery that blew was also FLA but a single 12v battery. My battery boxes are not sealed, have a series of 1” holes in the lids but the lids are locked to comply with CAT1.

[CF32907]

Originally Posted by CharlieJ

@Yandina
Your advice is contrary to good engineering practice and does not comply with the voluntary ABYC Standard E-10 Storage Batteriess:


All lead acid batteries will vent hydrogen gas as part of the normal charging process; some more than others. The vent in the battery box cover is to ensure that this highly explosive gas does not accumulate in the pocket formed by the cover.

Charlie, the comments I wrote, is not my advice, I'm just giving the facts. If you do not think there good engineering practices, you need to take it up with the USCG and ABYC. As a matter of fact, if you read my blog again, I said I would have proper boxes. Read ABYC again, it does not say you have to have boxes if you comply with USCG standards of proper securing. ABYC gives three acceptable methods for batteries. Boxes are not mandatory. Read it slowly so you can understand it.....

[CharlieJ]

@CfF32907 #39
Where did this come from?
My comments were clearly directed to Yandina not you as I am in agreement with your Post #31.

I recommend that you take your own advice and “Read it slowly so you can understand it...”.

BTW, I read and comprehend quite well.

Apology accepted.

[john61ct]

Just because a given authority recommends or mandates something, does not mean it is wrong to do otherwise,

unless you are required to follow them.

It is often the case rules go overboard, just as many are too lax.

Many issues are judgment calls with no consensus among the experts.