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RV Tech Savvy: Refrigerator Makes Battery Go Dead

Originally Published in MotorHome Magazine

Red letter Q

I own a Four Winds 5000 Class C. I have a problem keeping the refrigerator running when dry camping. The battery goes dead before the day is over with just the refrigerator running; everything else is off except the carbon monoxide sensors. I have a solar panel on the unit, but it will not help. If the refrigerator is off, the solar panel can keep the battery charged all the time. The battery only goes dead when the refrigerator is on. Is there a way to find out why when the propane refrigerator is on the battery will start to lose its charge within a couple of hours? Does having the refrigerator on make something else come on which drains the battery?

Mike Morgan | Rio Vista, California

Teal letter A

Essentially, the three likely culprits are: You’re either not getting enough current when charging the battery bank, the battery capacity is diminished due to age or sulfation, or the refrigerator is drawing excessive current. You didn’t mention what size your motor­home’s solar panels are, or what capacity the battery bank is, which are important factors here. I’d start by measuring current draw from the refrigerator. If the refrigerator has a three-way function, make sure you are not running it on 12-volt DC power. Additionally, test the battery with a load tester and test the charging system. I think these checks will solve it. Please let me know.


Using CPAP Machines


Red letter Q

We own a 2016 Thor Windsport 30-foot motorhome. My wife and I both use CPAP machines while we sleep. We would like to know the best way to have enough electricity for dry camping. In our previous motorhome we installed extra 6-volt house batteries and that worked fairly well. But only one of us used a CPAP then. We are hoping that you know about a better way to get this accomplished.

Wayne Smith | Agoura Hills, California

Teal letter A

Have a tech question?CPAP machines use a considerable amount of electricity over time, as you probably know, and it’s easier if you connect to shorepower. However, there are many types of CPAP machines designed for travel, and their current draws vary considerably. Some are even available with travel battery packs. Start by checking the current draw of each machine. Many owners report that by leaving the heated humidifier function off, they can reduce current draw substantially when running on battery power. To calculate power demand in ampere-hours, multiply amp draw by the number of hours they will run (typically eight hours). If you only know the watt draw, divide watts by 12 to get amps at 12 volts. Keep in mind that if you are using an inverter to get 120-volt AC power, it uses some current too, so add a fudge factor of 10 percent or so. Once you have your total amp-hour requirement you can estimate the capacity of the deep-cycle batteries needed to power your machines through the night. Batteries should not be drawn down below 50 percent capacity, as doing so will dramatically shorten their life, so allow for a generous reserve and don’t forget that other items are drawing current too. Large 6-volt deep-cycle batteries provide the best bang for the buck over time. If you don’t plan to recharge the batteries each day, you will need to multiply the amp-hour requirement by the number of days before you recharge. For dry camping, you also can’t beat a solar panel battery charging system to help keep your power supply up to snuff.


Vegas Fuel Economy


Red letter QWe are considering buying a 2017 Thor Vegas. Do you have any idea what the fuel economy might be?

Richard E. Gonzales | Via email

Teal letter A

As the commercials say, your mileage may vary, and it’s very true. The way you drive, speed, acceleration, traffic, elevation, wind and gradients cause huge variations. The Ford V-10 engine tends to be a bit thirsty, but the Vegas’ body design is more aerodynamic than many other motorhomes using that powerplant. Fuel economy is a touchy subject and no matter what I say, somebody will probably be unhappy with my answer, but here goes: Based on a number of owner reports, I suspect that in normal use (not steep mountains or towing) and at legal speeds, you are likely to get roughly 7.5 to 10.5 mpg, with most reports falling between 8.5 and 10 mpg.


Dim Dash Lights


Red letter QI have a 2011 Freedom Elite Class C on a Ford E-350 chassis. The dash lights are so dim, I can barely read them in the daylight. Is there a way to make them brighter? I have them turned up to max.

Russ Reynolds | Shrewsbury, Pennsylvania

Teal letter A

Find a bulb on that circuit that’s relatively easy to get to and measure the voltage going to it, and compare that to the voltage going to other items at the fuse panel. It could be that the dash light rheostat is faulty, or the bulbs have a bad ground. If the dash lights are getting significantly less voltage with the dimmer switch at full brightness, you will likely have found the culprit. I solved a problem with dim dash lights recently on one of my vehicles by installing LED bulbs in place of the old-fashioned tungsten filament bulbs. They will maintain brightness at lower voltages; however, you lose some of the ability to dim them.


Ken FreundRV DIYRV TechRV Tech Savvy

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