What Makes a Good Battery Hold-Down for a Boat?

Stainless hold-downs can work in the right installation, but non-conductive materials like fiberglass or nylon strap are preferred.

25th March 2013.
By Ed Sherman

Question: You can see in the photo I sent that on my boat the builder decided to use a metal bar to hold my battery down. I’ve also seen people use a wooden block or even nylon straps. What is really the best choice for this application? I’m a little worried about the metal being exposed to corrosive battery fumes.

Battery hold-down

The stainless steel hold-down for the maintenance-free battery shown should work fine in this case, but non-conductive, corrosion-resistant materials are better.

Answer: ABYC Standard E-10 is pretty clear on this one. It reads: “Battery mounting materials shall withstand electrolyte attack.”

What isn’t clear in the above statement is for how long.  The piece of angle stock you show on your boat looks to be stainless steel stock. Certainly it has the strength required to do the job as long as the fasteners, which are not visible, are appropriate and threaded into something solid. As for the issue of electrolyte attack, you have a maintenance-free battery shown in the photo. Even though you see caps at the top of the battery, these are not to be removed and in fact may be glued shut. This battery is not at all prone to gassing or electrolyte leakage due to its internal chemistry and case design.

Today your hold-down material choices are wood, aluminum angle stock, mild steel, stainless steel, nylon strap, carbon angle stock, and fiberglass angle stock. I prefer the non-conductive choices, combined with electrolyte exposure immunity. So, for me the top choice is an appropriately sized piece of fiberglass angle stock, minimum 1/8″ thick. It won’t corrode and it doesn’t conduct electricity.

I’m OK here with the stainless because I know that the exposure to corrosive gasses is absolutely minimal in this case. That piece of stock will last for years. Aluminum bar stock is a bit more reactive to both battery cleaners and acid exposure, so I do not consider it the next best choice. Mild steel will rust. Just remember, if you do use metal, be very careful not to create a short-circuit across the battery terminals when working on the battery.

Wood could rot pretty quickly if exposed to acid, and the carbon is too expensive as well as conductive once you expose the ends of the carbon fibers. As for the nylon straps you often see, they will never corrode. However, if they’re exposed to UV for a few years they will lose their suppleness and strength.


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About the author:

Ed Sherman

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Ed Sherman is a regular contributor to boats.com, as well as to Professional Boatbuilder and Cruising World, where he previously was electronics editor. He also is the curriculum director for the American Boat and Yacht Council. Previously, Ed was chairman of the Marine Technology Department at the New England Institute of Technology. Ed’s blog posts appear courtesy of his website, EdsBoatTips.
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http://www.EdsBoatTips.com

One thought on “What Makes a Good Battery Hold-Down for a Boat?

  1. We’ve had good luck with both fiberglass angle stock and nylon straps. Both are non-conductive, and these have been extremely durable (especially the fiberglass). But it’s always good to check on these at least once a quarter — more often in a salt water environment, or if the battery is exposed to a lot of vibration.

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