That would be a very spendy way to power an electric blanket! The electric blanket will take 60 to 200 watts depending on size. Also the temperature both set on the blanket and ambient temperature. (depends on how much of the time the blanket is running)
Buy a "Kill A Watt" meter (about $30) it should be in every boat owner's kit. It will tell you how much the current draw is, and it will also tell you how much over a period of time: You plug it into the wall mains 110 V socket, and then the appliance into the Kill A Watt meter. It will give Volts, Hz, Amps, Watts, and total Killowatt hourscummulative. For example if you use the electric blanket at home, you can turn it on when you go to bed at night, and then look at the KW hours (or fractions) in the morning, and it will tell you how much it uses.
Basically the "suitcase power supplies" are a lithium battery and a inverter. You are probably better off buying your own battery and charging set up. Don't depend on solar in most of those setups. I have seen C Brats show up with one, and then be disappointed in that it didn't give the power needed. Basically if you want a robust system, it is DIY putting together premium LiFePO4 Batteries, with 12 volt charging capacity (Sterling battery to battery charger, or Victron B to B) and quality inverter, plus proper fuse, proper size wiring etc. Also battery monitor system. I use Victron 702 or 712 monitor.
Lets say it uses 100 watts X 8 hours (That would be 800 Watt hours or 0.8 KW hours) that is about 12 amps x8 hrs or about 96 amps. If you had two goup 31 batteries it would deplete them by about 50%. (as much as you want to draw down). If you had one 100 Amp hour battery LiFePO4 ($ 925 each) it would be marginal...
A decent "power station" for 1000 watt hours, would be in the $1000+ range. Some do not charge from 12volts, or require a pure sine wave inverter to charge the battery,
A good sleeping bag is a lot cheaper...and probably healthier..Even when living aboard we never used an electric blanket. (Including 5 seasons in AK)
Bob thanks for the links--most interesting and good info. What I am concerned about in the C Dory is how batteries perform in the marine environment and with the G loads and vibration we see in the boats. I went with Battle Born-=US company using quality cells, good engineers on site, who know what they are talking about and the construction is robust.
