Yes, I saw your response ... I don't know what makes you think that I thunk what you think I thunk!Scott, I've explained my battery design in Post #32, didn't I? What makes you think I only have two small batteries? I have a good sized house bank and a small reserve, NOT start, bank. All this is explained in those links I keep posting.
In ALL of our discussions about this, MS & I have been very clear on what we have: large house bank, small reserve bank. NOT two equal house banks. Have no idea where ya got that from.
The assumption that two banks should be the same is way outdated, back before I bought my boat in 1998. That concept, the old two equal house banks, has been shown to be wasteful, since a larger house bank works better than two smaller ones of equal capacity.
Below are posts by Mainesail concerning the Dual Circuit switch.Mitiempo says that DCP is for small boats where each bank is small and equal. That's not the case. I use it exactly how it is intended. I have 200ah deep cycle using 2 batteries on main bank and a start batt on start bank.




If I was more than a daysailor I would configure them as 2 separate banks. No different to me than fuel in an airplane - would you want to be totally out of fuel when the tank was dry or would you want a reserve to switch to?So, if you were to equip your boat with just 2 batteries, how would you configure them assuming they are similar deep cycle batteries? Would you combine them on 1 bank for better efficiency and life and not bother with a reserve bank? .... or would you put one on Bank 1 and the other on Bank 2 for reserve?
I think my answer would be that I would combine them on one bank and forego the reserve if I was monitoring the bank (knowing they are healthy by monitoring them).
I'll second that.If I was more than a daysailor I would configure them as 2 separate banks. No different to me than fuel in an airplane - would you want to be totally out of fuel when the tank was dry or would you want a reserve to switch to?
My preference would be the 2 batteries in one bank with a reserve battery that was large enough for an engine start but not overly so.
I guess that says it all.Thanks for that, mitiempo, I remember reading those issues so I have wired my alternator output to the house bank. I also would not combine the start batt if I had a dead house bank ... there is no need to. I've never experienced an internal short, and never heard of one either. I don't worry about a lot of things that maybe I should. I often wonder how I ever survived!![]()