Sump pump backup: 12V or 110VAC with inverter?

Discussion in 'General Electronics Chat' started by french_guy, May 31, 2013.

  1. french_guy

    Thread Starter Active Member

    Apr 16, 2009
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    I want to install a sump pump backup in my basement - When it rains a lot, my main pump kicks in quite often
    I have a generator, but I am not fully covered if I am not here when power goes down, or if my main pump fails

    So I want a battery operated backup
    I have 2 options: a 12V system (such as Wayne ESP 25 or Watchdog basement) directly powered by the battery, or a regular sump pump (110 VAC) powered by the battery thru an inverter (1,200 or 1,500W I guess)

    But I’ve heard that the inverter option will give less autonomy, since the inverter itself will consume energy even at idle, and is not 100% efficient either

    However, how can I find out the difference in terms of autonomy: is it going to be only few % less with an inverter, or the impact is much bigger than that and I am better off with a 12V pump?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    I would go with the 12 volt system. Less power consumption than with the inverter setup. Plus with a 12 volt system you can have it completely separate from your main power, you could get a solar panel to keep the battery charged (to not put any more load on your generator, and make it completely "self contained"), and install a bypass relay/switch to activate the 12 volt backup when your main power is shutoff....
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I second that fwiw
     
  4. french_guy

    Thread Starter Active Member

    Apr 16, 2009
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    Either way i was planning to use a 12V battery:
    Option A: 12V battery + 12V sump pump
    Option B: 12V Battery + 12VDC/110VAC inverter + 110VAC sump pump
     
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I say option b. Option a will need a float charger on it anyway which (i think) negates any efficiency savings over the inverter. Plus you don't have to buy another pump, which is likely the most expensive part of the upgrade.
     
  6. french_guy

    Thread Starter Active Member

    Apr 16, 2009
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    Well, I will need a trickle charger for both options anyway, since it’s a backup running out of a 12V battery when the power is off
    And I still want a 2nd sump pump, to be protected as well in case the primary pump fails

    What will be more “easy” (less consumption) on the battery: 12V pump or 110VAC “regular” pump with inverter?
     
  7. BMorse

    Senior Member

    Sep 26, 2009
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    Depends on how much current a 12 Volt DC pump would draw versus how much the inverter + 110VAC pump would draw.....


    One good thing about using the inverter option is that the inverter (if it has the capabilities) will cut off the power when the battery level gets too low (and sound an alarm), versus a straight 12 volt pump, which would run until the battery is useless...... and if you are not going to be using a deep cycle battery, discharging it below 10 volts will cause issues with an SLA battery, and you may have to replace it more often than you would prefer... but then again with a 12 volt system without an inverter, you could use a low battery cut off circuit to prevent the battery from discharging too low. So there are pro's and con's to both systems, you will just have to choose the best option for you.
     
    Last edited: May 31, 2013
  8. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Sorry, when you said "inverter" my mind overwrote that with "UPS".
     
  9. #12

    Expert

    Nov 30, 2010
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    My preference is, "The simpler, the better". Even if the inverter was 100% efficient, it is still another part that can break, and a high tech part, too! You simply can not repair an inverter in a partially flooded room with a pair of pliers and a wire coat hanger, but you can steal the battery out of your car in an emergency.
     
  10. french_guy

    Thread Starter Active Member

    Apr 16, 2009
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    Yes, that's right.........
    But in that case I will have to find a circuit (low voltage cut-off) to prevent to discharge the battery too deeply
     
  11. strantor

    AAC Fanatic!

    Oct 3, 2010
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    An UPS has a circuit like that...
     
  12. BMorse

    Senior Member

    Sep 26, 2009
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