Low battery cutout settings

[Mack Turner]

At what voltage does everyone set their inverter to cut off so it doesn't damage your flooded batteries?

[Fred Brooks]

   Mack,
 The default setting from Magnum for the RC-50 remote (LBCO) is 10.0 VDC. Fred

[Mack Turner]

Thanks for answering Fred, I saw that in my book for the Magnum but then you read online  and they say not to drain a flooded battery more than 50%?  So at this point I'm about as clear as mud on where it should be set, I thought these golf cart batteries could take being drained down to almost nothing and still return but I'm no battery expert either.

[Fred Brooks]

   The inverter is not very efficient. As a matter of fact the inefficiency is a ratio of 10 to 1. If you were to turn on the microwave and run it off the inverter, the microwave draws about 12 amps of 120 volt power but the inverter draws 120 amps of 12 volt battery power to create the 12 amps of 120 volt power. Even if the 4 batteries were fully charged, that momentary demand would drop the voltage down somewhere around 11 to 11 1/2 volts. Now granted the microwave would only be on for 5 minutes or so, as soon as it turned off the voltage would jump back up to 12.6 or 12.7 because you have 460 amps capacity.
  As far as discharging the deep cycle batteries, the rule is to not discharge them more than 50% of there voltage. A fully charged battery is 12.7 or 12.8 volts dependent on the type and manufacturer. 50% discharged is 12.3 volts. That is when it should be charged back up to "float" That is considered "one cycle". Hope this helps, Fred

[Bill Lampkin]

The 'inverter' in our motorhomes are quite 'efficient'; efficiency is listed in the mfg specs and inverters are  about 98% 'efficient'. What Fred is getting at is better explained by the term watts, a measure of work.  Ohms law; volts x amps = watts (of 'work' or 'power'). For our microwave example, 120 volts x 12 amps = 1440 watts. Or, 12v x 120 amps = 1440 watts.  So to do the same amount of 'work', you have to draw 10x the amps from a 12v battery as compared to a 120v source. Its the same amount of work, no matter the voltage. Simplified I know, but I hope it helps.

Happy Holidays to one and all!!

[Bill Lampkin]

I just looked up the efficiency of my Xantrex Freedom SW 2012 inverter. Manual says 90% efficient.

[Fred Brooks]

   Thanks Bill for the explanation. Inefficiency may not have been the best choice of words. I am just trying to explain in layman's terms what happens when you put a large demand on the inverter. If you set the LBCO at too high a setting, the inverter may drop out while your using it. Merry Christmas to All. Fred