Do AGM batteries need to be in boxes?

[Cpt Pat]

Originally Posted by Tillsbury

Yes, as long as they’re very securely bolted down in a tray I don’t think AGMs need a full box.

I agree. You can bust open an AGM with a sledge hammer and it won't leak a drop.

But fail to secure it, and it can turn into what was once literally called a "loose cannon." Think upside-down. What happens if the boat is inverted? Does it punch a hole in the cabin top? Don't count on the battery cables to hold it dangling in space (yes, I've actually heard people propose that solution).


These are the hold downs that I use: https://www.odysseybatteries.com/hdk.htm

[meirriba]

The AGM battery would not leak if cracked.
However - it MUST BE SECURED in its place against shifting during sailing in heavy weather.
While having the battery in a box or on deep tray is always a good idea, the issue of securing the battery is not just a good idea - it is a commandment.

[tarian]

Originally Posted by john61ct

question was AGM specifically

emits much lower volume of actual liquid

some SLA are sealed but "Flooded Wet", more liquid can be released if they explode or are physically damaged

_____
And yes **of course** ALL battery types need to be securely held in place, against shocks or even a full turtling

Yes it was I was giving an example of mine, and as AGM are prone to overcharging , which can cause them to vent vapour. again do you want this all over your electrics , go ahead smash it up with a sledge hammer all you like but a simple fault in charging will produce water vapour all over the place and last I heard water and live connections do not go to well

[john61ct]

AGM is not nearly as susceptible to overcharging as GEL, and the gasses vented from any sealed battery from gross overcharging are a tiny volume,

water vapour content is harmless and insignificant; it's the acid in the fumes that is harmful to electronics

which is why they should not be installed right over the bank in any case.

And finally, that compartment should have good ventilation.

[john61ct]

But yes, if your care of your batteries means they are likely to explode, I suppose best that they are in an acid resistant tub of some sort.

[CharlieJ]

#12
This is an out-dated excerpt from the E-10 Standard.

From the current E-10 Standard:

10.7 INSTALLATION
NOTE:When installing flooded batteries on a sailing vessel, consideration should be given so that the orientation of the battery minimizes the uncovering of battery plates while heeling.

10.7.1 Battery mounting materials and surfaces shall withstand electrolyte attack.

10.7.2 Provision shall be made to contain incidental leakage and spillage of electrolyte.

NOTE: Consideration should be given to:
1.the type of battery installed (e.g. liquid electrolyte or immobilized electrolyte).
2. the boat in which the battery is installed (e.g. angles of heel for sailboats, and accelerations for powerboats).

10.7.3 Fasteners for the attachment of battery boxes or trays shall be isolated from areas intended to collect spilled electrolyte.

10.7.4 Batteries, as installed, shall be restrained to not move more than one inch (25mm) in any direction when a pulling force of twice the battery weight is applied through the center of gravity of the battery as follows:

10.7.4.1 vertically for a duration of one minute, and

10.7.4.2 horizontally and parallel to the boat's centerline, for a duration of one minute fore and one minute aft, and

10.7.4.3 horizontally and perpendicular to the boat's centerline for a duration of one minute to starboard and one minute to port.

[Cpt Pat]

Originally Posted by tarian

Yes it was I was giving an example of mine, and as AGM are prone to overcharging , which can cause them to vent vapour. again do you want this all over your electrics , go ahead smash it up with a sledge hammer all you like but a simple fault in charging will produce water vapour all over the place and last I heard water and live connections do not go to well

Badly abused or very new AGMs can vent oxygen and hydrogen, a very small amount of which could recombine into pure water. Pure water is an insulator. https://en.wikipedia.org/wiki/Purifi...l_conductivity. Fire and explosion is a bigger hazard with gaseous hydrogen, copious amounts of which are vented when overcharging or balancing (equalizing) flooded cells.

One of the reasons for using AGMs, in place of flooded cells, is their immunity from dousing everything with battery acid when the boat heels, is knocked down, or rolled. I've seen a number of lead/acids installed that, while they were in a box, that box lacked a water-tight top, making it useless for containing battery acid when the boat was in any unusual attitude. Vertical is a relative thing in a sailboat.

While AGMs prevent the crew from being blinded by acid flying around the cabin in a knockdown/inversion - all heavy batteries are deadly missiles (along with the engine) if they ever come loose.

[CF32907]

Hi all, CaptVR here, I was a marine surveyor for 20+ years. Know it's been fifteen years back, but here is the way it was to ABYC recommendations. They are recommendations, not requirements. Although if you want insurance, and it requires a survey, the surveyor inspects to ABYC and USCG requirements.
1. A battery box is not required, not even for a lead / acid battery. As a matter of fact, many boat manufacturers just install trays, very similar to cars and trucks. Acid containment is not addressed.
2. They did have to be secured, could not move more than 1" front to back, 1" side to side, and 1" up and down.
3. The battery box if so equipped had to have ventilation, as did the area the battery was located in. Many boxes are illegal, there not vented properly...
4. If there was no box to protect the electrodes, the positive post and wire connections required a red rubber boot to keep it from possible shorting, should something come loose or some one drop a tool to cause a short..
5. The battery could not be located over or under fuel tanks or lines
6. Batteries can not be placed in living quarters, other than in a designated single use locker with positive ventilation outside the vessel.
That pretty much covers battery placement that I remember. I no longer have the 4" thick ABYC manual, any surveyors out there please check me for correctness. Please, no one correct me if it does not come straight from ABYC manual. We have a lot of weakend sailors that do a lot of guessing.....
Take care all, Capt. Vince Rakstis, Ret.

[Fore and Aft]

My four AGMs are in a fibreglass tray and are very well secured. But my engine start battery is in a plastic box. Mainly because it is close to the engine and it would be the one place I might drop a spanner and short it out.
Cheers

[HopCar]

Strap the batteries down so they can’t move.
Cover the terminals so you can’t accidentally short across them with a tool when you’re working near them.

I mounted my AGM’s on their side on a flat platform. Had them that way many years with no problem.

[sailorman14]

The only way to really know the answer to that is to call the US Coast Guard and ask. They are the ones you need to please in that situation.

[john61ct]

What situation is that?

[Maine Sail]

Originally Posted by Stu Jackson

Nope. They still have acid in them and if the case cracks?

"Containment", in the ABYC context, is for catchment of any leaked electrolyte. Batteries classified as non-spillable eg: AGM batteries do not need a form of acid containment because even when broken open they don't leak electrolyte.

"ABYC E-10
10.7.2 Provision shall be made to contain incidental leakage and spillage of electrolyte.

NOTE: Consideration should be given to:
1.the type of battery installed (e.g. liquid electrolyte or immobilized electrolyte)."

I have asked and received ABYC standards clarification on the bold red areas. This was due to a survey where the surveyor flagged AGM batteries not in a plastic battery box (factory supplied by the ABYC boat builder).

An AGM battery that can't leak electrolyte does not technically need acid containment. A box is never, ever a bad idea but if space prohibits it, and the batteries can't "spill" or "leak" then there is no box requirement under ABYC standards for AGM batteries that can't leak.

All other ABYC requirements, do apply to AGM's however..

They do need terminal protection from shorting though. This can be in the form of terminal boots or a dedicated battery compartment with lid. They also need to be properly mounted and secured. Of course most instances of shorting battery terminals happens when the lid is off and you're working on the batteries. This is why stubby insulated battery wrenches are a great idea for battery work. Plasti-Dip is your friend.

If you have batteries that can leak electrolyte, the box into which they could leak acid needs to be acid tolerant. It also needs to be able to contain the acid in the battery without spilling to areas that are not acid tolerant, with consideration given to vessel type & usage. Containment, for batteries that have liquid electrolyte, should be capable of containment at angles of typical heeling on a sailboat.

Many boat builders molded fiberglass battery boxes, Ericson, Pearson etc., and those meet the requirement, as does a $6.00 plastic battery box. However if you put a SS screw through the bottom of the battery box or floor of a fiberglass battery compartment, as far too many people do, it can no longer withstand "electrolyte attack" unless the fastener is isolated so that acid erosion of the fastener would not allow the electrolyte to leak out....

If one needs a custom box, often better than a cheap Tupperware grade battery box, they are easy to custom build out of plywood.. You then drop it at a Rhino Liner and have them hit it with pickup truck bed liner.

Dry batteries, eg: AGM's, that can't leak electrolyte would not require accommodations for acid spillage or leakage, because they can't physically leak, but flooded batteries would.

When battery acid gets to keel bolts, it's not pretty, and it gets very expensive. I have seen far too many flooded batteries leak (typically at the welded seam) or crack and when there is no containment it gets nasty. Even with containment it can be a nasty mess of corrosion.

Perhaps the easiest method to determine whether acid containment is necessary is to simply read the MSDS for your battery or contact the manufacturer. I know of no deep cycle flooded batteries that meet the DOT or CFR 49 classification requirements for "non-spillable". Most all AGM batteries however meet the "non-spillable" requirements under DOT and CFR 49 as "non-spillable". If it does not meet this it is likely not a true "absorbed glass mat" battery..

[john61ct]

Hmm, bedliner. . .

good as the purpose designed acid-proof Battery Box Paint?

https://www.aircraftspruce.com/catal...lkfloatbtm.php

[slapt0p]

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?

Well you know that scene in Alien when it bleeds super-acid blood and it eats through the deck floor and down to the next deck floor....etc. etc.

https://www.youtube.com/watch?v=WYlhinRAM0I