I have a 12v appliance that I want to hook up to a battery. It uses 200 watts. Whats the smalled handheld rechargeable I can get to power this appliance? How long would it be able to run for? Im known to donate fg for correct answers.

assuming its a constant 200 watt draw you will need 17 amp hour battery just to run it for 1 hour.

for future reference the simple math for this is watts/volts=amp draw

then compare amp draw to how many amps the battery can sustain based on its amp hour rating.

So smallest battery suggestions?

depends on how much you want to spend and the situation it will be used in and what the appliance is specifically.

obviously a recharge option for the battery helps you keep it smaller but if you need to run it for like 4-5 hours you'll be needing basically another battery like your car but probably larger lol.

you'll be looking for a deep cycle dry cell battery so depending on how many hours you want to run it you just find the one with an amp hour rating similar to that

so 5 hours=85 amp hour deep cycle battery would be the minimum but ideally you want to have some extra on top to avoid dealing with too low of voltage for too long because it will begin to drop voltage over time.

that's basically going to be a battery similar to the one in a car so it really depends on what you call small lol.

also depending on location you may look into solar recharge solutions to avoid lugging around a huge reserve capacity battery in favor of solar charging+small battery.

I'm thinkng more hand held type battery only needs to last 1 hr?

well the math of the situation simply doesn't allow for it. 17amp hours at 12 volts simply requires a fairly large battery.

http://www.sonicelectronix.com/item_73094_Shuriken-SK-BT18.html for example would only cover 1 hour at those volt/watt requirements and its an 12lb battery.

the reason cell phones and flashlights and stuff get away with not using these large things is because they don't use 12 volts which eats up amps pretty quick for applications such as this.

We'll my appliance is a heating element. Also drill batteries last for 30-40 mins of heavy use looking for something like that I would assume.

You already asked here
http://forums.d2jsp.org/topic.php?t=71581251&f=90
And no FG

the best thing to do here is find out those batteries mAh rating then do a timed test on them for your regular use of the heating element.

once you know how long it takes to drain that battery you'll know exactly what size battery you'll need to get more out of it.

so if a 3 amp drill battery last 30 mins you'll know you need a 6 amp for an hour and so on.

came back to this later thinking i may of misunderstood what you said.

are you saying that drill batteries when used on a drill last 30-40 mins or saying you've used drill batteries to run the heating element?

i took it as the latter but i'm not sure lol