Power Consumption

[Jerry Winchester]

This one I can't quite figure out.

Tied on to shore power here in Las Vegas. Kicked the three Cruisair units on. About a minute later, the breaker trips. I reset it and it trips again.

I go check to see what all is running. I turn the inverter battery charger off along with the AquaHot electric heater and any other potential power hogs. The fridge is still online since I can't really shut it down.

Get the AC's back on line and they run thru the night okay. Hey, its only 105 deg. here at 3pm. But when I look at the meters, with all the stuff on, we are only consuming 40-45 amps (both legs added together). I would have thought 50am service would have handled that, but I swapped spots at the park and have the same problem.

Is this normal? I don't know if the AC units are pulling more power because of the high ambient temperature or what, but there won't be any battery charging unless I shut down one of the AC units or put the power share for the inverter at about 5 amps.

I shut down one of the units this morning in the interest of beauty so the blow dryer, etc. could be used, but I would have though you could push it closer to 50 amps before I shut down. However, my generator won't keep up with all the ACs and the old battery charger I had, so maybe that is just life.

[Jon Wehrenberg]

Jerry,

On a shore power outlet of 50 amps you literally have 100 total amps theoretically available, 50 on each 120 V leg.

I don't know how your volt meters or amp gauges are set up in your coach, but lets assume you can read each leg individually. Each leg should read a nominal 120 V. If it gets lower the amperage will rise. If it gets below 110 you need to pay close attention, because your ACs will start to shut down in another 4 or 5 volts of drop.

Assuming however your voltage is high enough, your three ACs when running will draw about 39 amps (13 each), but if they cycle on and off the starting current will be considerably higher. It is possible your hot water heater will draw about 12 amps, a refrigerator about 5, and your battery charging system could draw some more and maybe a lot more depending on how you have it set up.

The leg with 2 ACs will be at 26 amps, add something else and it is possible you are over 40 amps. The industry seems to accept that you can run 80% of rated amperage all day long, but once over that value you could trip the breaker. Lower voltage equals higher amperage so your breaker tripping could be a combination of factors. There is also a possibility that the connections to the breaker in the box are loose and if that is the case you are not the cause.

There may be another issue in play because if your generator cannot keep up with things it is either a small one (12.5KW) or you have too much load on one leg.

[truk4u]

Jerry,
I just went through this exercise while at the races, even though I was using the gen (20KW) the problems are similiar. Jon is dead on, as voltage drops, amps rise. My problem is not getting a good 120 Volts on each leg from the gen, but the power management is the issue.

If your getting less than good volts (120 each leg) from shore power, you just have to cut back the usage like you are doing. I even had to adjust the Trace Inverters to go to float charge during high power usages to keep all three A/C's, coffee pot, hair dryer, etc working during those demanding times when Ms. Truk must have more power than a nuclear power plant.:o

The real killers were the bulk chargers and water heater. I have two bulk chargers and they suck some serious amperage. I also have two water heaters that take as much amps as the chargers. I just let the webasco take care of the water and manipulated the chargers to get by. I would then go back to bulk charge and let them do their thing.

I haven't yet been plugged in where I had two good legs of 120 each, but I doubt that all 3 A/C's, bulk chargers and other loads will run. You would also be surprised the amp loads with just all the stuff you have plugged in as well as the phantom loads of AC.

MORE POWER Scotty........:p

[ken&ellen]

There is a good article on Prevost-Stuff.com about the Trace Inverters and bulk charging. Maybe you could sneak onto the site in the middle of the night as not to stir up the natives.:p and read it.
On the Trace you can adjust the absorsion time to zero and go to float charge. You can also adjust the voltage on float higher so that the batteries do not require the bulk settings. Ken or as I was known in the electrical business " Ready Kilowatt ":D

[truk4u]

I already do all that Mr. D J and I visited the site in the day time along time ago before I converted to the dark side! Did you just now read the article oh great record spinner?:D Now my gen is making 120 on both legs and life is good.

Get your speakers ready for Myrtle big boy.:o Ex mooney pilots have wierd tails.