Ice as a battery

[LakeSuperior]

Originally Posted by owly

It's frankly amazing how complicated people can make things in pursuit of automation. just separate solar panels into banks with switches. Designate some to feed the charge controller, and some to the chiller. Have switching available so you can change that balance if needed. Solar is cheap these days. If you don't manage it like a computer would, it isn't the end of the world. Being able to monitor the state of charge so you can redirect intelligently is important.

There is a reason people use refrigeration systems that operate like shore refrigeration systems. Battery weight on monohulls is not particularly important, and it's easy and effortless................ My interest is in multihulls where every pound matters. I'm willing to manage my charging to keep weight down.

H.W.

There are a few problems with a manual control system.

House power consumption fluctuates from day to day so the total solar power required to top off batteries is variable, therefore, the excess power available to freeze water will vary.

The amount of power available to charge house batteries and freeze water is further confounded by daily variations in solar loading on the solar panels.

Consequently, the time at which to switch over the system will different every day.

Human presence onboard to switch power is not a given. What if you are diving, sightseeing, etc.

Do you want to be onboard every day to check the meter every hour in order to manage the charging? Not me.

[owly]

Originally Posted by LakeSuperior

There are a few problems with a manual control system.

House power consumption fluctuates from day to day so the total solar power required to top off batteries is variable, therefore, the excess power available to freeze water will vary.

The amount of power available to charge house batteries and freeze water is further confounded by daily variations in solar loading on the solar panels.

Consequently, the time at which to switch over the system will different every day.

Human presence onboard to switch power is not a given. What if you are diving, sightseeing, etc.

Do you want to be onboard every day to check the meter every hour in order to manage the charging? Not me.

There is no question that it's a problem...... what isn't? Automation creates it's own problems. During the day if you are not around to maximize the efficiency manually, of course, you can simply draw off the battery while the charge controller feeds charge the battery, and let the normal thermostatic control manage things, and just not worry much about it. When you are trying to "bank ice", you might dedicate some solar to just the freezer, and crank it to max, and some to the battery bank. A look at the forcast, and at your needs, and some human decision making is called for. You have so many amps to play with, you know your state of charge, and have a good idea how much ice is banked..... You make a decision. Alternatively you can have a system with more batteries that mindlessly cycles a refrigerator. It all depends on your willingness to make decisions and be involved. There is a reason most people just use a mindless refrigeration system and buy batteries enough that they can ignore it. It's easy.
I'm looking at it from a different perspective than you are. I'm willing to inject some human management into the system to have fewer batteries. The life of all batteries is based on the total energy stored and retrieved. As with the choice of the boat itself, the perfect boat for me is completely unsatisfactory for someone else. That's true with much of what we do. I'm obviously willing to mess with it more than you are. Hopefully you can bank enough of both battery charge and ice and fresh water, that it's never a crisis.
H.W.