[C320-list] Battery Capacity calcs

[Angus Henderson]

Daryl. I can’t comment on your calculations, only my own experience with a similar battery system consisting of 4 GC batteries for the house bank and a separate start battery. I have the standard alternator and a 160 W solar panel on top of the davits.  The frig is always on but not necessarily running. Most days cruising on Georgian Bay the batteries are back up to capacity by 13:00 and even on cloudy days I do not have to run the engine to charge.  I also sail almost all the time as I dislike motoring and choose not to go out if there’s no wind. 
So I would highly recommend your proposed set up with a solar panel. 
Gus
Hull #999
Georgian Bay




Sent from my iPhone

> On Dec 31, 2019, at 2:19 PM, Daryl Hunt <drhunt at rochester.rr.com> wrote:
> 
> I have two relatively new (2018) Interstate SRM-4D flooded lead acid (FLA) deep cycle batteries on my '99 C320 #660 "Believe."  I plan to wire them in parallel and add a starting battery as several in this group have done.  Wanting to also add solar panels to extend time at anchor.  To determine what kind of off-the-grid performance I can expect I've studied articles and YouTube videos and think this is what I currently have:
> 
>     SRM-4D Reserve Capacity = 390 min @25A;  Amp Hours = (390/60) x 25A = 162.5 AH
>     House Bank Reserve Capacity = 2x 162.5 = 325 AH
>      According to Jeff Cote of Pacific Yacht Systems, for FLA batteries:
>      Practical/Usable Capacity = RC x .35 = 325 x .35 = 114 AH
> 
> This is a bit disappointing.  Given refrigeration and modest use of other DC draws, I can only expect ~1-1.5 days before recharging.  Solar panels on the bimini may supply 20-40 AH on a sunny day here in the Great Lakes might extend that to 1.5-2 days.  Can someone check my math and assumptions?  I'm now beginning to see the real advantages of AGM and Firefly.
> -- 
> Best regards,
> Daryl Hunt
> 
> S/V Believe, 1999 C320 #660
> 
> Pittsford, NY - Lake Ontartio
> 
> (585) 233-7814
> 
> -- 
> Best regards,
> Daryl
> 
> (585) 233-7814
>