Amps

[bwells]

My house has a 200 amp main, 2 pool pumps on a 50 amp breaker, AC/heater on a 50 amp breaker as well. Worm drive skillsaw likes 20 amps as does my compressor. All of the above are A/C but my cabover camper has four electric jacks that lift 2500 lbs on a 40 amp breaker DC. How on earth does a tiny motor need 100-200 amps? I assume it does but just can't get a handle on it to explain it to others! Thanks.

[m4a1usr]

My house has a 200 amp main, 2 pool pumps on a 50 amp breaker, AC/heater on a 50 amp breaker as well. Worm drive skillsaw likes 20 amps as does my compressor. All of the above are A/C but my cabover camper has four electric jacks that lift 2500 lbs on a 40 amp breaker DC. How on earth does a tiny motor need 100-200 amps? I assume it does but just can't get a handle on it to explain it to others! Thanks.

Is there a motor of EACH jack? Or one motor for all 4?

John

[mm123521]

Bwells'

Your house total power: 200 amps (the main circuit rating) TIMES 240 volts (voltage coming into your house) = 48,000 watts of power

Your boat total power: 200 amps TIMES 22 volts (6S) = 4400 watts

Its the voltage!
Your house is running on 240 volts (two circuits of 120 volts), thats over ten times as much voltage as your boat. Your house is the equivelent of 64S !
Your boat is only 22 volts, so needs alot of amps to generate a few horsepower.

Just think, if you had 64S in your boat and your motor drew 100 amps, that would be = 24000 watts = 32 horsepower!!

At 64S there would be a lot of electructed boaters!!

Mark

[bwells]

m4a1usr: nope, 4 jacks running at the same time
mm5321: Scratch the house stuff, where does these tiny little motors get away with needing this amperage? From what I understand amps is current draw which is work done. I know it is needed (amps) but trying to get a reason why.

[ls1fst98]

how are you getting 100-200 amps? if its on a 40 amp breaker and you pulled 100-200 amps you would be tripping that breaker.

[jac4412]

bwells look at your setup... in order to get the required horsepower to run your boat look at what the boat needs with a limited voltage, high amp draw in comparison to other things

[ls1fst98]

never mind i think i see what you mean now....youre wondering why an rc boat pulls that many amps. scratch what i previously said lol

[Make-a-Wake]

how are you getting 100-200 amps? if its on a 40 amp breaker and you pulled 100-200 amps you would be tripping that breaker.

I'm thinking he means how does an FE boat draw these high amps................

[bwells]

Yes sir, Why does an FE boat pull these kind of amps? I'm thinking there is a waste area where the excess goes. Not sure, still guessing'

[ls1fst98]

its not waste, it needs the amps to make teh hp we ask them too. since we can not feed 120 volt to these motors. since amp=watts/volt and since voltage is low, and the wattage we need is high (since watts equalt hp) the amperage draw has to be high. more volts available to make the same watt, the less the amp draw is.

i know i may be slightly off but im pretty sure thats how it is.

so if we want a motor to make 1000w at 14.4v you would have 1000/14.4=approx 70

now take that same 1000w at 120v you get 8amp.

[bwells]

Good post, a lot of info there that I need to absorb. Thanks

[GP73]

If I may, I think his question might be rephrased like this:

Why do you need 1-2 kilowatt of power to move a "little" boat.

Mass and friction? Plus there is surely a lot of energy wasted if you are using the wrong propeller...

http://en.wikipedia.org/wiki/Watt

[ls1fst98]

well his initial question i think was why do these small motors pull so many amps, but either way, all good info tohave and to understand.

[bwells]

Yep, exactly. Still pondering ls1fst28 post and trying to get a handle on it. I know there is a reason for 200 amps but I need to see it in math terms which he explained.

[ls1fst98]

glad i could be of a small assistance then. i know like if you look at your pool pump, it will most likely a daul tap 120 or 240 volt pump. it is more efficiently run at 240 volts. same with an a/c compressor.

the math boils down to A=W/V which means that AxV=W. in a house power the higher the voltage something runs (light ballasts, pumps, etc) the more energy efficient they become due to the lower amp draw, and thus lower wattage, which is what you pay for. in the rc system, you are demanding a finite system to generate a certain wattage to get teh HP you want out of a motor. a lot of that turns into heat energy which technically is wasted energy, which is why we try to minimize heat. so when you have a set voltage from a battery pack, and a set wattage a motor is capable of putting out, the amperage is what will increase. this is also another reason that a higher volt setup will draw fewer amps.