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#### Batt

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##### In Remembrance
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OK, I'm confused. It has been so long since I have done any electrical math, it doesn't count.

Here's the situation: I'm adding a fireplace with an insert & blower. Blower is 1/150th horsepower. I'm thinking a Solar cell to a 12v. Gel battery to an inverter to the blower. Possibly a trickle charger from house current if needed...Wait and see.

I understand that a 1HP motor is 746 Watts. Is this independent of the voltage? i.e. 746 watts @110v = 746 watts @ 12 v.? I'm just getting lost.

#### ace admirer

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yes, power = voltage x current . regardless of magnitude

thats the easy part...you have to figure the efficiency of the conversion from solar cells to the final mechanical output. the inverter efficiency will probablly pull more than the motor.

also the name plate hp on the motor is not actually what the motor will mechanically do... usually fully loaded motor will actually be at 80% of name plate hp. a one hp motor will be fully loaded and near overloaded if run at .8 hp for a length of time. the current draw therefore wattage will vary depending on actual mechanical load on the motor...in this case a varable of cfm and pressure the fan will be working against...

might you consider a 12 volt dc blower instead of the ac? something from surplus center maybe?

#### bbbuddy

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##### Registered
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Adron said:
OK, I'm confused. It has been so long since I have done any electrical math, it doesn't count.

Here's the situation: I'm adding a fireplace with an insert & blower. Blower is 1/150th horsepower. I'm thinking a Solar cell to a 12v. Gel battery to an inverter to the blower. Possibly a trickle charger from house current if needed...Wait and see.

I understand that a 1HP motor is 746 Watts. Is this independent of the voltage? i.e. 746 watts @110v = 746 watts @ 12 v.? I'm just getting lost.

"watts is watts", no matter what the voltage is, so 746/150= 4.97 watts is all you need to run the blower.

That's so low, it would not be hard to hook up a small solar cell, cheap inverter and one 12 volt battery, just not very cost effective if you already have power.
If you are off grid aren't you already making power? I do, and I wouldn't even notice 5 watts run for 24 hours...
either way, I would just plug in to my regular power.

#### radiofish

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##### Semper Fidelis
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Well Power = Current X Voltage (P=I X E) as pointed out above, using either 110 Volts AC or 12 Volts DC.. Current is I = P/ E (Current = Power/ Voltage). Simple Ohms law to find the missing value needed to solve the problem.

I would follow the advice and find a suitable 12 VDC fan instead of having an inverter, producing 120 VAC, etc. Anytime you convert DC to AC Voltage, you will experience a decrease in the efficency of your system output. Look for a good brushless DC blower style fan and you should be able to set it up much cheaper than the original design you proposed.

#### ace admirer

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