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Author Topic:   Shock absorbtion for batteries
anthonylisske posted 07-09-2009 10:50 AM ET (US)   Profile for anthonylisske   Send Email to anthonylisske  

I posted a while back about having a AGM battery break due to pounding. I am scheduled to go back offshore in a month or so, so I was just looking to get some input on how to pad the batteries.

1973 21 foot outrage
dual series 7 AGM batteries
Batteries located in console
Floor of console cut out and battery holder mounted to deck

Expected use:
Offshore 100+ miles
To run in 6-8 foot seas (Not planned, but I usually run into some waves either gong in or coming out)

I did some research on shock/vibration materials. There is a myriad of materials out there and it is not easy to distinguish the better product without holding it in your hands.

Isomode Pads (made by Gilbert Industries) is a thing of the past. They looked perfect though.

There are a lot of other products out there, but when I look at shock loads they are usually in Pounds per Square inch.

Naturally, I always want to get the "best" product, but that is where it gets confusing.

My first inclination is to get a high "pounds per square inch" type, but then I see that the max loads models actually have a steel plate in them for use with drop hammer type of machinery. Not so Good.

My second thought was to go with the middle of the road "pounds per Square inch", but those models have a cork center sandwiched in between 3/8 inch neoprene. Is the cork a bad idea with oils, fish guts, and saltwater constantly drenching it? I dont know.

The bottom tier is usually a 3/8 piece of rubber or neoprene, which in my mind is a wet suit material that is very "squishy" and would be pounded to dust within a week.

I would appreciate some direction.

Thank you

pglein posted 07-09-2009 12:04 PM ET (US)     Profile for pglein  Send Email to pglein     
Impact Gel, as seen on Pitchmen:

Warning: site auto-loads a Billy Mays video, complete with yelling!


pglein posted 07-09-2009 12:05 PM ET (US)     Profile for pglein  Send Email to pglein
Dan posted 07-09-2009 12:06 PM ET (US)     Profile for Dan  Send Email to Dan     
Try this place:

I would just put a piece of dry dek underneath the battery box, or even inside the battery box under battery.

Jerry Townsend posted 07-09-2009 03:15 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
You have several options - much better than a thin layer of rubber - or other make-do's. You mention Isomode pads - which in my minds are the best - but go to

damn - forgot how to make this a direct link. ---- Jerry/Idaho

bluewaterpirate posted 07-09-2009 03:37 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
I have two AGM's installed on my 210 Ventura midships under my helm. These two batteries have been beat to hell for sure. I had two floor mats that came with my VW Passat that I didn't use (the nice thick rubber ones)so I cut them to fit the trays under my batteries. Four years later not one issue.

Biggest thing is to ensure they're securely tied down to the deck area where you have them mounted.

Here are aome pictures ..... Image-4892322-31023578-2-Web_0_26aa058eaec5d89fa685d1f25ba27d15_1 Image-4892322-31023594-2-Web_0_02764c3b90acc0052767fb186818fd41_1

Jefecinco posted 07-09-2009 07:35 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
If the batteries are absolutely perfectly secured to the deck with strong hold-downs then there can be no impact between the batteries and the deck. So, did the battery break on the bottom or was the fracture above the bottom caused by insufficient strength of the plates, separators, and securing structure, thus allowing movement in the battery interior?

Is it just me or would others think it likely that if a battery failed structurally due to pounding at sea then the boat structure would also be threatened?

Slowing down when conditions are extreme would do far more to maintain the structure of a battery than mounting it on a semi-rigid pad.

If your damaged battery was solidly mounted to a solid deck it would indicate a high probability of a defective battery.


anthonylisske posted 07-09-2009 11:07 PM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Thanks for the quick responses, pictures and links. I am going to research it some more and try to figure out.


anthonylisske posted 07-09-2009 11:11 PM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Thanks for the quick responses, pictures and links. I am going to research it some more and try to figure out.


anthonylisske posted 07-10-2009 10:45 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Just re read your comments. The break was inside the battery. (It looked fine from the outside)

I was hoping it was defective manufacturing, but I want to hedge my bets by installing some type of shock absorption. losing a battery that far out would really kill my buzz.

Jefecinco posted 07-10-2009 07:35 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     

Certainly no harm will be done by using some sort of shock absorbing pads under your battery.

If I were you I'd go back to the battery manufacturer and ask for an adjustment due to the internal failure of the battery which is indicative of a manufacturing defect. AGM warranties tend to be for longer periods than for standard lead acid batteries.


anthonylisske posted 07-11-2009 09:48 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Yes, the company replaced the battery and prorated me about 75% of the purchase price. I was satisfied with the customer service.

The night it happened I was driving out to the canyon off montauk NY and took a horrendous beating. (6-8 footers at night)

davej14 posted 07-11-2009 10:09 AM ET (US)     Profile for davej14  Send Email to davej14     
Most of us strap down the battery boxes and not the batteries within the boxes. The photos from bluewaterpirate illustrate one of of each method. It would seem reasonable that a shock absorbent material inside of the battery box would lessen the shock loading the battery experiences. If I were routinely going 100 miles offshore I would take every precaution to have reliable batteries. Especially if the motor could not be started without them.
bluewaterpirate posted 07-11-2009 10:58 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
The one in my battery box has two sets of straps one set inside and the other outside. I cut small holes in the bottom of the battery box so the deck fasteners can have access into the battery box.


davej14 posted 07-11-2009 10:01 PM ET (US)     Profile for davej14  Send Email to davej14     

Why am I not surprised that you have it all figured out !!

Still, I'll bet most of us just leave the battery inside the box to "rattle around". In this case a shock absorber of some type should be helpful.

anthonylisske posted 07-12-2009 08:28 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     
I actually do not have battery boxes, but trays. They have a tray at the bottom that is screwed and 5200ed to the deck, then they have a "ring" piece at the top that grab the circumfernce of the top of the battery. The top ring and bottom tray are bolted to each other by long stainless bolts. They are very secure to the deck.

I bout the trays at west marine a few years ago.

Just figured I would add that fact for consideration. (I should have done it earlier)

bluewaterpirate posted 07-12-2009 10:13 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Anthony .....

Those are great battery trays .... Many boat builders use them.



bluewaterpirate posted 07-12-2009 10:14 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Sorry .... 4892322_3310080_61696679_WebSmall_3/ Image-4892322-61696679-2-WebSmall_0_7ea7593402bf66ce4bc9598473c6f2aa_1

Newtauk1 posted 07-12-2009 01:28 PM ET (US)     Profile for Newtauk1  Send Email to Newtauk1     
I use a battery box secured to the deck with the supplied strap. I snugly fit pieces of Dri-Deck between the sides of the battery and the inner wall of the battery box. I do this to ensure the battery is not moving with in the battery box. Anywhere there is a gap between the battery and the box I wedge a piece of Dri-Deck.
anthonylisske posted 07-12-2009 08:03 PM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Dead on! That is exactly them. They have worked great. Thanks for the post.

bluewaterpirate posted 07-14-2009 05:28 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Here's some better pictures of what I was talking about ..... I changed battery brands .... went with Odessey. Batteries%20545%20BEP%20716/Odessey1.jpg?t=1247606679 Batteries%20545%20BEP%20716/Odessey2.jpg?t=1247606737 Batteries%20545%20BEP%20716/Odessey4.jpg?t=1247606808 Batteries%20545%20BEP%20716/BEP7162.jpg?t=1247606856


anthonylisske posted 07-14-2009 06:50 PM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Nice setup. I really appreciated the last photo. Looks like a great set up with the isolators etc.. and bus bar.

Any chance you could explain the set up. I will email you. I may want to change my cable routing set up to yours.

ScottS posted 07-15-2009 01:49 PM ET (US)     Profile for ScottS  Send Email to ScottS     
The best way to reduce battery damage from vibration is to mount the battery in the stern. The stern is the pivot point when the boat hits waves and it has the least movement. Plus, in the stern means shorter wire runs to the starter motor. Obviously, other factors like needing to move weight forward can make a stern installation impractical. Make sure whatever items you use to reduce vibration can handle contact with battery acid and gases.

Some of the battery mounts shown in these pictures don’t appear to meet ABYC boat building standards (it’s hard to tell from the pictures). First, don’t cut holes in the bottom of the battery box or trays. One purpose of the box is to collect spilled electrolyte (acid) to prevent it from causing damage. Second, use straps that resist damage from battery acid. The red straps appear to be standard cargo tie down straps. These may break when exposed to battery acid and the buckles may rust from exposure to the vented battery gases. Third, the picture of the three batteries in the trays appears to have exposed positive terminals, which could result in a short. Finally, if your batteries are inside the center console (or other closed area), then make sure the console has good ventilation. Hydrogen gas from the battery vents needs to be vented out or you can have an explosion. Ventilation is required even if you have sealed batteries since a future owner may switch battery types.

ABYC Standard E-10.6. Storage Batteries - Installation
a. Batteries shall be secured against shifting.
b. Each installed battery shall not move more than one (1) inch in any direction when a pulling force of ninety (90) pounds or twice the battery weight, whichever is less, is applied through the center of gravity of the battery as follows:
(1) Vertically for a duration of one (1) minute
(2) Horizontally and parallel to the boat’s center line for a duration of one (1) minute fore and one (1) minute aft.
(3) Horizontally and perpendicular to the boat’s center line for a duration of one (1) minute to starboard and one (1) minute to port.
c. To prevent accidental contact of the ungrounded battery terminal to ground, each battery shall be protected so that metallic objects cannot come into contact with the ungrounded battery terminal. This may be accomplished by means such as:
(1) Covering the ungrounded battery terminal with a boot or nonconductive shield,
(2) Installing the battery in a covered battery box, or
(3) Installing the battery in a compartment specially designed only for the battery(ies).
d. Each metallic fuel line and fuel system component within twelve (12) inches and above the horizontal plane of the battery top surface as installed shall be shielded with dielectric material to protect against accidental short-circuiting.
NOTES: 1. Terminal insulation or battery covers do not comply with this requirement since during installation or removal of a battery, these protective devices are usually removed in order to connect the cables.
2. Any nonconductive material maybe used for shielding as long as it is durable enough to withstand accidental contact by a tool or the battery terminals during servicing, installation or removal.
e. Each battery shall not be installed directly above or below a fuel tank, fuel filter, or fitting in a fuel line.
NOTE: This does not prohibit a battery from being installed directly above or below an uninterrupted fuel line; however, if this fuel line is within the twelve (12) inch envelope of the top surface of the battery it shall be shielded dielectrically as required in ABYC E-10.6.d.
f. A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery. Battery boxes whose cover forms a pocket over the battery shall be vented.
NOTE: These provisions also apply to installations of sealed batteries.
g. If the mounting surface or components of the boat in the immediate vicinity of the battery location are of a material attacked by electrolyte, a mounting means shall be provided that is made of a material that is not damaged by electrolyte.
h. Fasteners for the attachment of battery boxes or trays shall be isolated from areas intended to collect spilled electrolyte.

bluewaterpirate posted 07-15-2009 02:06 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Scott .....

That's where BW installed them to start with. There is a tray inside the the battery box the battery sits in to prevent spillage into bilge ..... the outside straps are there as a backup to the primary one & to hold the lid in place. There is no room in the stern area to install batteries plus there is no ventilation. The primary straps are certified for battery use.

They key to these installs forward is using the correct size primary battery wires.

The picture of the three batteries was how the dealer installed them ..... it's not a finished product. By the way there are doors that close in front of that install.


L H G posted 07-15-2009 06:39 PM ET (US)     Profile for L H G    
I don't believe in batteries mounted in consoles for older Whalers, but if you do, the system that works for me in the stern will work just as well in the console.

Take a look at this photo, and others around it: current=R1-5.jpg

Basically, I use the original Boston Whaler system, which includes the SS Footmans Loops for the strap hold downs, the BW Kev-Lock over-centering battery strap and latch (the best you can buy, period) and a piece of DRI-DECK cut to size. Any battery box can then rest on this, which cushions the battery and distributes it's weight via all the little plastic/rubber "feet" while at the same time allowing dirt and water to run underneath it. No abrasive damage is done to the gelcoat finish. Any needed clean-up is simple.

anthonylisske posted 07-16-2009 11:19 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     
Jeez LHG, Even you splashwell looks pretty!

Thanks for the picks, maybe dri-dek isn't such a bad alternative.

ScottS posted 07-17-2009 10:34 AM ET (US)     Profile for ScottS  Send Email to ScottS     
Tom, I guess I misinterpreted your comment above, "I cut small holes in the bottom of the battery box", and thought that meant there were holes that spilled battery acid could go through. I didn't realize you have another tray inside the box to contain spills.

I understand that Whaler installed your battery in the console. That's where my dealer put mine too. My comment about mounting it in the stern was aimed at others who may be considering moving their battery from the stern to the console. Unless they have a strong need to move it (like better weight distribution) it's going to last longer in the stern because of reduced vibration. A strong mount like your's and LHG's that doesn't allow the battery to slide around is a big help too.

Larry, that is a beautiful splashwell!


number9 posted 07-18-2009 05:25 AM ET (US)     Profile for number9  Send Email to number9     
Are the ABYC Standards available other than through them(big $$$)? It sure would help consumers when making modifications, help identify non-compliance items and may help with warranty issues.

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