Disabling LV alarm

sepsolman411sepsolman411 Registered Users Posts: 16
Is there a way to disable the low voltage alarm buzzer on the circuit board in a pure sine wave inverter? Some manufacturers set the voltage alarm too high. The one I have starts buzzing at 11 volts. I want to disable the buzzer but not the shut-off function. Any advice is appreciated.

RCinFLA wrote: »
12.2 vdc open circuit is a nearly dead battery to start with.

If you have done the math correct, I assume your comment about a 1.5 kWH battery means a 125 AH, 12v battery. Maybe two Walmart Everstart MAXX-29 series.

Alarms on inverters are usually set for 10.5-11 vdc.

For that sized inverter, depending on total wire length, should be using at least #4 wire, preferred #2 wire.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: battery voltage drop/inverter alarm
    Is there a way to disable the low voltage alarm buzzer on the circuit board in a pure sine wave inverter? Some manufacturers set the voltage alarm too high. The one I have starts buzzing at 11 volts. I want to disable the buzzer but not the shut-off function. Any advice is appreciated.

    Welcome to the forum.

    How comfortable are you with opening up your inverter and poking around inside it? Got a schematic? They're not all the same by any means. The bigger ones don't have an alarm; just a shut-down. But somewhere inside yours is likely a piezo-electric buzzer that screams like a banshee when battery death is imminent (sorry - bad jokes are my stock-in-trade). It is also likely to be this that sounds when other faults occur such as over-Voltage or over-current or whatever that particular unit is designed to complain about.
  • sepsolman411sepsolman411 Registered Users Posts: 16
    Re: battery voltage drop/inverter alarm

    I have already opened up the inverter and probed around looking for the buzzer on the circuit board. There is no schematic that came in the box and I looked online at the OEM. Here is the link to my PSW-500: http://www.12vgridtiepowerinverters.com/ProductProfile/PSW500-12-110. After thinking about the other variable faults that you mentioned, I now do not want to shut off the alarm. My quandary is how do I upgrade from a 35amp hour sealed lead acid battery to accommodate a 60 watt solar panel in a 5.50 hour solar day. In other words, do I basically need a 120 watt solar panel and a 100 amp hour 12 volt sla battery to run a few small appliances at night for a few hours? These appliances include a notebook computer, 3 cfl bulbs on a lamp, cell phone charger, printer, tv, and cable box but running all at one time.
    Welcome to the forum.

    How comfortable are you with opening up your inverter and poking around inside it? Got a schematic? They're not all the same by any means. The bigger ones don't have an alarm; just a shut-down. But somewhere inside yours is likely a piezo-electric buzzer that screams like a banshee when battery death is imminent (sorry - bad jokes are my stock-in-trade). It is also likely to be this that sounds when other faults occur such as over-Voltage or over-current or whatever that particular unit is designed to complain about.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: battery voltage drop/inverter alarm

    Do you have any way of measuring your AC power usage--such as a Kill-a-Watt meter or equivalent?

    Ideally, before you purchase any (more) solar pv/battery hardware, measuring your loads and defining your needs will help a lot.

    Generally, you would want to run a 100 AH 12 volt battery at a maximum of 10 amps * 5 hours for long battery life (50% maximum discharge, C/10 discharge rate):
    • 10 amps * 5 hours * 12 volts = 600 Watt*Hours
    With various losses, that is around 100 watts for 5 hours of AC loads...

    It could be done with that battery--But you probably would want more solar panels... The normal first cut estimate for running 500 WH per night with 5.5 hours of sun:
    • 500 WH * 1/0.52 system eff * 1/5.5 hours of sun = 175 watt minimum solar panel
    And that is assuming you get 5.5 hours of full noontime equivalent sun per day, or better (never plan on using 100% of available solar power every day--probably 50-75% of available average power per day).

    Of course, if you have backup power (grid, generator, etc.) or the loads are optional (don't use the TV+Cable tonight because there were clouds today).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Disabling LV alarm

    In terms of sizing batteries & panels you need to have a target number for your loads. As in 'X' Watt hours per day. That number divided by the system Voltage (in this case 12) gives you an approximate Amp hours needed. The battery needs to be at least twice that size. Then the panel should be sized to provide not only the "replacement" Amp hours during the available charge window (5.5 hours) but also the recommended potential peak charge current (5%-13% of the total Amp hour capacity).

    Is that confusing enough? :p
  • icarusicarus Solar Expert Posts: 5,245 ✭✭✭✭
    Re: Disabling LV alarm

    Just to be clear,

    All battery/charging calculations begin and end with the loads. Any other method merel results in chasing ones tail.

    Tony
  • sepsolman411sepsolman411 Registered Users Posts: 16
    Re: Disabling LV alarm

    Very good, I appreciate the prompt moderator feedback for answering my questions as well as how to calculate ac loads. Thanks to each of you. :D
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Re: battery voltage drop/inverter alarm
    ... to run a few small appliances at night for a few hours? These appliances include a notebook computer, 3 cfl bulbs on a lamp, cell phone charger, printer, tv, and cable box but running all at one time.

    WOW, speaking of loads, unless your shutting down in under 1 1/2 hours, that's more loads than I ran when I had a 220 watt array and 220ah 12 volt bank!

    I think you should look at how much your using, and the needs to use TV and Laptop at the same time, 3 cfl's at the same time, etc.
    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 more...lol
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Disabling LV alarm

    that alarm is there for a reason and that is to protect the battery from being depleted too far. if the loads are too heavy for the battery capacity it will draw down the voltage quite a bit. it could also be that the battery has lost its capacity due to age and/or heavy cycling. as was suggested, you should pin down the loads more precisely over time with a meter like the killawatt. batteries should not be taken below 50% dod as a general rule. 50% of a 220ah 12v battery is 110ah and that translates into 1320wh plus there will be an extra draw for the operation of the inverter in the area of 10-30%. rounding this off to say 1500wh and over 2 hrs would represent 750wh of use per hour. it could be that the battery has been taxed too much too often an if you fail to reach a full charge with your solar then this compounds the problem by allowing the battery to not only go below 50% dod, but it can sulfate as well if it persists.

    i recommend checking the electrolyte levels with bringing it to a full and proper charge and the checking of the specific gravity of each of the cells.
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