How long 1 cir. pump run on car battery?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by ozzie88, Nov 8, 2012.

  1. ozzie88

    ozzie88
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    I need to be able to run a taco 700 cir. pump on a battery just wonder if you have an idea how long a pump could run on a good car battery? or should I have couple of them, Just one pump with an inverter
     

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  2. danjayh

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    You need to make a lot of assumptions to figure this out. First let's assume you're using a 40 Amp-Hour battery that hasn't degraded in capacity at all. Next let's assume that your power inverter is 90% efficient, and that your taco pump draws about 80 watts (this varies depending on the head).

    80 watts / .9 efficiency = 89 watts needed from the battery by the inverter
    89 watts / 12 volts = 7.4 amps drawn by the inverter
    40 Amp-Hours / 7.4 Amps = ~5 hours

    Note that this would be under ideal conditions, and I wouldn't be surprised at all if in reality you got an hour or two less than that.
     
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  3. ozzie88

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    Thanks for the info on this, it gives me a good idea now what I need to do,,
     
  4. Bob Rohr

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    You can also buy DC circ pumps. I've used these on solar systems powered from a 30W module, or power them from a battery. That would save the cost of the inverter and the efficiency loss thru it. Not as powerfull as that 70W pump, but it may be enough for your application.
     

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  5. Floydian

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    Bob, thanks for always posting such interesting hydronic toys!

    Has Laing always been a part of Xylem or is this something new? Also, have you ever used the El Sid pumps?

    Noah
     
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  6. Bob Rohr

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    maybe a year or more for the Laing/ Xylem partnership?

    I have not used the El Sid. I have used and removed a handful of the Marsh 809 12V DC pumps. Very durable, noisy and not as efficient as the ECM based Laings however.
     

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  7. flyingcow

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    FWIW, sometimes I can buy a comm truck battery for as much money as a car battery.
     
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