Re: Inverter to run microwave and elec heater what size?
Depends on total wattage Ron. If the microwave is about 650w I've found that they actually take more to run it; maybe 800-1000w or more. If you plan to run a heater or a microwave off a battery you won't be able to run it for any reasonable length of time w/o the engine running and even then your alternator might not be able to keep up. Same with any heavy load. I can run mine for short times... 5-7 min w/o trouble as long as it's set to a lower power w/o the engine running. Even if I have the engine running, using the MW on high pulls more than what the alternator can supply and it still depletes the house battery. You can go longer if you have more battery power like 3 220ah batteries but those are heavy, costly and take up room. Also pulling real heavy loads off a smaller battery can do damage the battery itself, so I'd suggest a generator.
 think about this, will a 1500 w hair dryer keep your van warm? There are some lower amp heaters but most are well over 1000w. Kinda why My Buddy sells so good.
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