Inverter question

blueskiesblueskies Registered Users Posts: 32 ✭✭
Hello friends,
I have an inverter question.  I got a Samlex 3000 watt/24 volt inverter.  I trust this is an efficient brand of inverters based on research and recommendations.  It will be ideal for running high watt loads for about 30 minutes around noon - such as my Haier washer (tiny and efficient, holds about a milkcrate of clothes).  The manual states the inverter uses about 1 amp when no load is connected.  However, When I plugged a led bulb into it, I noticed the battery levels go down faster than expected.  So when the unit is in operation, even with a small load it draws a good deal and I should probably have a separate inverter for small loads.  Am I on target or way off in this deduction? 

As a side note - I have a midnite kid and plan to use that for an independent 12 volt system in a separate room.  I like this because it seems much easier and more economical for setting up a diversion 5 gallon water heater when the batteries are charged and not being drained by tv/computer.  What do you think?

Thanks in advance and also for all your insight in the past.


  • EstragonEstragon Registered Users Posts: 4,451 ✭✭✭✭✭
    Some inverters have an idle "search" mode, in which they pulse voltage once every second or two, but otherwise use little current.  If a load over a certain size is connected, they "wake up" to supply the load.  Being awake to supply a small load can be pretty inefficient.  Very small loads, like a phone charger, may be too small to wake the inverter, and will pulse with the inverter probe pulses.  I don't know if that's how the Samlex works though.

    In general, smaller inverters have smaller idle losses, and run small loads more efficiently that larger ones.  If only using the big inverter as described, turning it off and using a smaller inverter the rest of the time may not be a bad idea.  For simplicity, I'd wire the big inverter to big load circuit(s), and small inverter to other circuits. 

    I have a lockout panel which lets me choose which inverter to use for some circuits (eg cabin lights), and a separate panel with circuits (eg pumps) which can only use the big inverters or generator power.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • NANOcontrolNANOcontrol Registered Users Posts: 169 ✭✭✭
    As for the water heating, you do what you can do.  I heat water (an ECOsmart 6 gallon and a feeder tank) right off the panel voltage thru a power point controller, if you have at least a 36V string. I take a dim view of these diversions thru the battery. I use a fixed power point voltage to decide how much power is diverted to water heating and it is highly effective. No screwing with batteries charge cycles.   You look like you might be up to building a little electronics.
  • blueskiesblueskies Registered Users Posts: 32 ✭✭
    Thank you both.  I will use all the knowledge provided.
  • PhotowhitPhotowhit Solar Expert Posts: 5,101 ✭✭✭✭
    I wonder what size battery bank you have, a 3000 watt inverter and with a Midnite Kid a max 1200-1400 watt array, max 30 amps would indicate 220-300 amp 24 volt battery bank... Seems like an over sized inverter for that size system...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • blueskiesblueskies Registered Users Posts: 32 ✭✭
    The Kid is on an independent 12 V system, different panels and different area.  The 24 v is on 2-series/2-parallel 12 v 100 AH Solar wind agm sla deep cycle vrla batts.  The 4 panels that go to the morningstar TS mppt 60 which is just within its recommended input level.  Always good to hear from you, any input appreciated!
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