[C320-list] Battery Capacity calcs

[Daryl Hunt]

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