You should also be aware that there are different types of chemistry in AGM 
batteries. My new ProNautic charger has 4 different programs for charging AGM 
batteries, and at least one of those is pretty much identical to the programs 
available for lead-acid. But the instruction manual for the charger tells you 
to be sure to contact the battery supplier to identify the exact type of AGM 
you are using so you can be sure to setup the proper charging profile.

 

Have you thought about going to Lithium batteries? A boater on my dock is in 
process of installing 4 of them on his O’Day. Cost of the batteries is about 
$300 each – which isn’t dramatically higher than good AGMs, His bank will be 
between 400 and 500 AH (I forget exactly what he told me), but with Lithium 
batteries you can use more than 50% of the bank capacity without harming the 
batteries… you just need the correct charge profile (and a higher capacity 
charger).

 

Rick Brass

Washington, NC

 

 

 

From: CnC-List [mailto:[email protected]] On Behalf Of Josh Muckley 
via CnC-List
Sent: Tuesday, October 16, 2018 9:14 AM
To: [email protected]
Cc: Josh Muckley <[email protected]>
Subject: Re: Stus-List AGM Batterries

 

I don't think a formalized commercially available box is specifically required. 
 If you find references contrary please let me know. However "battery boxes" 
serve multiple purposes beyond acid containment.  Properly engineered and 
installed boxes ensure that a loop seal is maintained such that water cannot 
get in the box should the boat flood.  They simultaneously allow gasses to 
escape, and provide battery encapsulation.

 

Here are a few references.  

 

https://www.passagemaker.com/technical/the-large-battery-bank-equation-part-i

 

https://www.uscgboating.org/regulations/assets/builders-handbook/ELECTRICAL.pdf

 

https://marinehowto.com/installation-orientation-of-flooded-batteries-on-boats/

 

ABYC E-10 is the pdf I was looking for but unable to immediately source.  ABYC 
is similar to the underwriters laboratories.  They don't write the law but they 
do make industry standards for safety which will likely define whether or not 
an insurance claim will be paid.  The electrical pdf above gives reference to 
the CFRs.  The actual law.

 

AGM are a type of lead acid technology.  They are not at risk of spilling their 
acid and can be mounted at varying angles and orientations.  They can vent 
gasses, though when they do it is permanently damaging to the battery.  If you 
delve into AGM be mindful of the stringent charging differences and make sure 
that all of your charging sources (shore power charger, alternator, solar) are 
changed to match.  Do not under any circumstances allow an equalize to be 
applied to an AGM.  Any voltages above 14.6v will cause permanent damage.

 

Josh Muckley

S/V Sea Hawk 

1989 C&C 37+

Solomons, MD

 

 

 

On Tue, Oct 16, 2018, 7:51 AM pete.shelquist--- via CnC-List 
<[email protected] <mailto:[email protected]> > wrote:

I’m not sure where to reference the regulations/guidelines on this, so if 
someone can point me in the right direction I would appreciate it. 

 

I would like to add a couple more batteries and am looking  at AGMs due to 
their tolerance of being at an angle.  Since, as I understand, they are not 
technically a lead-acid, do they still need to be installed in a battery box?   
I’m very tight on space and could use the extra few inches.

 

Thanks,

Pete

 

 

  

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