I'll give it a shot, but I'm not an engineer, just someone who had to figure it out for my RV. First off, from my experience with the 340 the startup draw is only while the igniter is on, so it's just a minute or 2. That being the case I wouldn't let it enter into the calculation, but if you want to then
2 minutes @ 350w = 12w, 12w/12vdc=1 Ah
10 hrs @ 50w = 500w, 500w/12vdc=41.6 Ah
Total needed for 10 hr run = 42.6 Ah
Inverter overhead .5 A, .5 * 10 = 5 Ah (this may vary depending on the inverter, fwiw my rv inverter is 1000w and is 1.2A)
Total Ah required = 47.6 Ah
Inverters also have an efficiency rating, a 300w inverter may have an 80% efficiency, meaning it sucks in more power then it puts out. So if we use 80% (mine is 90%), you'd use another 9.5 Ah, or 57.12 Ah total
In general, it is suggested you keep battery draw down to 50% or less for the longest battery life. That being the case you need a Deep Cycle battery of at least 114 Ah
Chances are you won't find a 110 Ah battery that's affordable and if you did it might be too big to lug around. If you went with a Group 24 deep cycle you can get a 100 Ah which is manageable. You'll need to discharge it a bit beyond the 50% line, more like 60%, but that's not the end of the world for as little as you're likely to use it.
If you use MasterTech's numbers you'll see the 100 Ah battery would be fine.
I read somewhere that you should get an inverter that's 30% higher wattage then you figure you need. No idea why.
2 minutes @ 350w = 12w, 12w/12vdc=1 Ah
10 hrs @ 50w = 500w, 500w/12vdc=41.6 Ah
Total needed for 10 hr run = 42.6 Ah
Inverter overhead .5 A, .5 * 10 = 5 Ah (this may vary depending on the inverter, fwiw my rv inverter is 1000w and is 1.2A)
Total Ah required = 47.6 Ah
Inverters also have an efficiency rating, a 300w inverter may have an 80% efficiency, meaning it sucks in more power then it puts out. So if we use 80% (mine is 90%), you'd use another 9.5 Ah, or 57.12 Ah total
In general, it is suggested you keep battery draw down to 50% or less for the longest battery life. That being the case you need a Deep Cycle battery of at least 114 Ah
Chances are you won't find a 110 Ah battery that's affordable and if you did it might be too big to lug around. If you went with a Group 24 deep cycle you can get a 100 Ah which is manageable. You'll need to discharge it a bit beyond the 50% line, more like 60%, but that's not the end of the world for as little as you're likely to use it.
If you use MasterTech's numbers you'll see the 100 Ah battery would be fine.
I read somewhere that you should get an inverter that's 30% higher wattage then you figure you need. No idea why.
