View Single Post
Old 01-17-2015, 01:32 PM   #3
twistedtree
Guru
 
twistedtree's Avatar
 
City: Vermont
Join Date: Jan 2013
Posts: 10,092
I run two alternators. One is 180A for the house bank, and the other is 85A for the start bank. Both are controlled by Balmar smart regulators.

At least one of the guys who has my boat's twin has dual 180A alternators, both charging the house bank. Then he uses a DC/DC charger to indirectly charge the start bank. At some point I will likely do something similar with my 85A alternator. Under normal conditions the start bank gets charged back up quickly and the 85A alternator is doing nothing. I'd rather split the load between the two alternators with each running at the same % of it's rated output. Obviously the bigger one would always be delivering more of the current, but that's what it's supposed to do.

The DC to DC chargers are made exactly for this, and I believe only turn on when the house bank is at a high enough voltage to be receiving a charge itself. So you are never charging by actually drawing power out of the house battery - just diverting charge from the alternator. I think the Balmar Duo is an example of such a device, but I might not be remembering the name correctly. Echo Charger is the other name I have heard. Anyway, I've got lots of other things higher on my project list for now, but some day I'll get to it.
__________________
MVTanglewood.com
twistedtree is offline   Reply With Quote