question

drommen avatar image

AGM Super Cycle mounting position limitations?

I am replacing my house and starting batteries on a 36' sailboat and was ready to buy a pair of the 12V 230Ahr AGM Super Cycle batteries for my house bank as they will fit perfectly in my 4D size tray if they are installed on their small sides with the long dimension becoming the vertical height.

The dealer I wanted to purchase from said these cannot be installed on their side "...you have to lie these down in the way they are designed, you cant stand them upright. They are heavy and the plates hang from the top side so when you mount them vertically their weight is inadequately supported and prone to breakage in the event of a bump in the road or a wave in the ocean. The same thing applies for all lead acid batteries but the bigger the battery the more the effect will occur."

I can understand this in a Jeep or or perhaps a fishing boat smacking through chop at 25 knots, but is there enough stability in a slow cruising 36' sailboat and mounted amidship that this would not be an issue? I was a bit surprised to hear this and wanted to find more opinions on this.


MPPT - Solar Charge ControllerinstallationAGM Battery
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2 Answers
Justin Cook - Bay Marine Supply USA avatar image
Justin Cook - Bay Marine Supply USA answered ·

@Drommen, your dealer has given you the proper response... never mind the Jeep or the chop scenario: gravity is a strong, inexorable pull that's always present, no waves or bumps needed, and lead is heavy. You could stand them on their side on a stable floor and, eventually, one or more of those plates would probably fail because the internal plate support structure is simply not designed or tested to withstand lateral stress on the plates like that configuration would cause.

These are sealed batteries, of course, so they can be installed on their sides or ends or any number of other configurations without their contents spilling out, but the question here is a matter of longevity; the internal plate supports are not designed or tested for installation in any configuration other than in the "normal upright" position, so it's anyone's guess as to how long such an installation would last before the battery internals failed, and considering that this could potentially have disastrous results -never mind the waste of a perfectly good battery- I must echo your dealer here and say that installation in anything other than an upright position is not recommended and not supported - that latter meaning that improper installation would not only likely lead to premature failure, but would also void their warranty, which is of course the last thing you'd want in this situation.

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drommen avatar image
drommen answered ·

The last thing I want to do is replace batteries prematurely and void warranties. This is making sense now and thank you for explaining further. I will try and do some more measuring this weekend and see what options I have. Thank you so much for your time. I know even at my work you will sometimes reach someone with a strong opinion that isn't necessarily correct, but they are steadfast about the topic so I thought it best to try and get a second opinion.


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Oh, understood... and it raised an interesting question and I myself went and studied the internal construction of these so I could be certain of my answer, since I would have thought that it might be fine to do... certain AGM manufacturers certainly do have units that can be installed on their sides, so I was willing to cede the possibility that your dealer was just blowing smoke... but after appropriate research, however, I came to the conclusion that they were in fact correct, since the Super Cycles just aren't constructed to deal with that orientation.

Cheers!