[C320-list] Batteries

[Scott Thompson]

It's a myth that AGMs cannot release hydrogen gas. They do vent under 
some circumstances. (They would be subject to explosion due to high gas 
pressure otherwise.) For this reason the ventilation issue is not solved 
by using AGMs. However since hydrogen is lighter than air, all you need 
is a small vent near the top of the battery compartment. A small 
louvered grill high on the side of the settee would do. See for example 
https://www.boats.com/how-to/sealed-batteries-still-need-venting/. That 
said, I've felt no need to add venting. I find it implausible that there 
would be enough hydrogen accumulation inside the battery compartment to 
cause a safety issue. Hydrogen is a very small molecule that is very 
buoyant and can find its way through small openings with ease. I'm 
confident that the settee is not sufficiently well sealed to prevent the 
hydrogen from escaping. If there is evidence to the contrary, I am 
interested, but I've never heard of a hydrogen explosion on one of these 
boats.

I'm still using flooded lead acid batteries. Apart from the need to top 
off with distilled water periodically I have found them to be trouble 
free and have felt no need to switch to more expensive batteries. I did 
add a separate starting battery, an upgraded battery switch (one that 
turns on the motor starter/alternator circuit and the house bank circuit 
at the same time while keeping them isolated from each other when not 
charging), a smart battery combiner (so that the house bank will charge 
once the starting battery is "full"), and a Victron battery monitor that 
shows charging or discharging current (or watts) in real time, and 
tracks amp-hours in and out. Also a Victron MPPT 15 solar charging 
regulator for my small solar panel. I've been impressed with the Victron 
hardware.

My boat lives mostly on a mooring and so the shore power charger is a 
non-issue for me most of the time. The small solar panel keeps things 
topped off nicely when I'm off the boat, and helps when we are cruising 
and on the hook. I've purchased a separate monitor for the solar panel 
but never gotten around to installing it.

Scott Thompson

On 7/11/2018 7:43 AM, Brian McLamb wrote:
> Hi Scott. I changed to AGM a little over a year ago. Survey recently have
> had issues on resale as new codes do not like Catalina battery placement in
> non vented area under couch. My charger unit had ability to change a
> setting switch to AGM from flooded battery so that much was fine. Years ago
> I added a starting battery and had alternator upgraded to handle the load.
> A smart regulator was also installed to manage the charge to the 3
> batteries. All has worked very well.
> S/V Serenity. # 1075.  Brian
>
> On Wed, Jul 11, 2018 at 7:26 AM Scott Westwood <scottwestwood at bellsouth.net>
> wrote:
>
>> OK.  Another loaded question:
>> I am trying to dig into the decision to replace the existing battery(ies)
>> or switch to AGM.  One of my Liquid Batteries is toast and needs to be
>> replaced.
>> AGM batteries are more than twice the price and it will "likely" mean
>> replacing my existing charger.  I need to verify that but I am assuming,
>> for now, that I will need to replace the charger I just installed 3 years
>> ago.
>> I understand the value of non-liquid AGMs and not having to keep
>> re-filling distilled water, heeling not an issue, etc....
>> If I go ahead and go to AGM and replace my charger, then I might as well
>> go ahead and get an upgraded monitoring system.  Right now I have the old
>> analog rocker switch and I would go/add a digital one that would show the
>> current load.  I always like the thought of knowing how much current you
>> are drawing "right now".  I added a remote panel monitor for the charger
>> when I replaced it so I have some sort of monitor but would be nice to know
>> current draw.
>> A co-sailor is suggesting I move to the West Marine 4D  at $790 each...
>> while I can replace the existing liquid LA for $280 each and keep my
>> charger.
>> Does anybody have any experience with longevity of the AGMs?  If they live
>> twice as long it might be worth it to do it all now.  If not then I don't
>> see the value.  I can replace these LA batteries every 5+ years and save
>> boat units.
>> May even think about adding a start battery??
>> Any thoughts out there?  Has anybody re-done all this and have
>> models/pics/experices etc....  Projects on the website?
>> I said it was a loaded question(s).
>> Thanks,
>> Scott Westwood scottwestwood at bellsouth.net H (919)-362-8538    C
>> (919)-618-7185
>>