Originally Posted by jakegator
OH! ok thank you, I completely forgot about that! Also, would you recomend have a DC battery bank and then one for AC to reduce the stress on the batteries or does it really not matter?
Even 14cf is a big fridge to find space for on a boat. How big is your boat?
You don't want to cycle the batteries below 50% very often (ie once a year or so). On the other hand it's hard to get them to charge higher than 80% or so. That means you get to effectively use 30% of the battery capacity, hence you want a bank 3x as big as the daily load with new batteries. The batteries will lose capacity over time, the bank should really be 4x load in anticipation of this. Since you probably won't be getting them up to 100% most of the time you want to do an equalization
process once per month. That's a whole 'nother topic.
I would go with 1 large house bank to run all house loads, and second bank with a single
battery strictly for engine
starting. My logic is that on a cool day when fridge demand is low, or on a regular day when other demands are low the house bank does not get drawn down as much which is better for the batteries, or on really hot days when the fridge demand is high you can choose to conserve other demands and hopefully keep the bank from going below 50%. If you split the batteries into separate banks each bank is more likely to go below 50% more often.
Optimally the 2 banks would each have their own alternators. The stock alternator
should be fine for the starting battery. I would add a little 5w solar
panel to trickle charge this battery constantly.
The house bank optimally would have a large capacity alternator
and a smart regulator
. I would talk directly with the battery manufacturer about the appropriate charging
protocol for their batteries and learn to program the regulator so it follows the correct protocol. The preprogrammed protocol is not necessarily the right one.
The solar panels
need a regulator too. There are 2 types:
PWM which costs about $200 and optimizes for longer battery life.
which costs about $600 and optimizes for more charge put into the batteries for a given amount of solar
The short-term costs seem to be an even tradeoff, less expensive controller but more solar panels
needed to put the same amount of energy into the batteries. Then the question becomes which is more of a premium, finding space to mount more panels
and using PWM or using the MPPT
and replacing your batteries somewhat more often.
Personally I would go with the MPPT.