Generator Is Not Charging Battery
Dear RV Doctor:
I have an older 31-foot Type C motorhome on a Ford E-350 chassis with an Onan MicroLite generator, model number 4KYFA261000B. One weekend while at a remote location, the generator was used for about 18 hours for the air conditioner and RV power, and then early in the morning the generator died, causing a total loss of RV power. The RV battery ran dead, so I assumed the trickle charger from the generator was not working. I started the RV engine and then jumped the generator battery to start it; it 0perated fine while the RV was running. Voltage at the battery was 12.1 to 12.2 with the engine and generator off. With the generator running, the voltage at the battery was 11.9 volts, which further makes me think that the battery is discharging and the generator battery charger is not working.
I read online that the rectifier bridge may be bad and in need of replacement, but I removed the generator and cannot find the bridge on this unit. Does the RV inverter under the rear bed function as a battery charger as well? If so, how do I troubleshoot that?
Harlan Foraker
Wichita, Kansas
Your generator, unfortunately, does not have a battery charge circuit. Spec A models did come equipped with a small battery charging circuit, but with Spec B, Onan configured only a battery charge module into their 50-hertz power plants, and, of course, here in North America, everything runs on 60-hertz electricity. In all honesty, I’ve always found the battery charge circuit to be less than stellar for charging some of the more robust battery banks. Far superior battery charging options exist. So, simply put, your generator is used only for AC output and will not recharge its own battery.
Most motorhomes rely on a charging converter or an inverter/charger to keep the house battery bank charged. It’s apparent that the inverter on your coach is suspect, if indeed it is equipped with a charging circuit. It could quite easily be something as simple as a blown fuse inside the inverter. In many cases, the inverter, which normally uses DC battery voltage and inverts it to 120 volts AC, becomes a very good, multistage battery charger when the coach is connected to shore power. It pulls double duty — removing amp-hours when inverting to AC, and charging amp-hours back into the battery system when connected to shore power. In my opinion, it is much preferable to have a charging INverter as opposed to a charging CONverter.
Check the literature that came with the inverter for the location of the fuse, or let me know the inverter brand and model number and I’ll do some further digging. Inverters either work or they don’t, so if you are still receiving 120-volt-AC output from yours, chances are the battery charge circuit has simply fallen prey to a blown fuse or a faulty connection.
Refrigerator Warm-Up
Dear RV Doctor:
I have a Norcold refrigerator, model 1210IM. The freezer compartment is 10 degrees while the fridge compartment varies from 38 degrees to 55 degrees. Until lately, the temperature stayed around 40 degrees. The thermistor is on the fourth fin from the right side, and the clip that holds it on the fin is rusted. Is this temperature variation normal? If not, could the thermistor be causing the problem?
Harold Southerland, F412055
Chapel Hill, North Carolina
If the thermistor were shorted or had an open wire, you would see a fault code on the display. I’m not aware that thermistors can become erratic or cause the issue you are experiencing without a fault code being displayed. But to be sure, there’s a quick and easy test you can perform if you’re handy with a digital multimeter (DMM).
Remove the thermistor from the fins and place it in a small container of crushed ice. Insert a thermometer in the container as well. Wait 10 minutes or so and check the temperature of the ice in the container. Use the attached chart to compare the temperature to the resistance measurement between the two thermistor wires. If the measurement differs drastically from the chart, replace the thermistor.
By the way, the thermistor should be attached to the second fin from the right, not the fourth. Clean the oxidation from the clip on the thermistor. All connections should be clean and tight. If the difference in temperature between the freezer and food-storage compartment occurs during a hot summer excursion, keep in mind that high (as well as low) ambient temperatures have a direct effect on the performance of the cooling core, as does high humidity.
If the thermistor checks out okay, look for obstructions in the chimney area behind the refrigerator. Be sure there is a clear ventilation space all the way up and through the upper refrigerator vent (either a roof vent or an upper side vent if the refrigerator is mounted in a slideout). There will be a relatively small gap between the back of the refrigerator and the inside portion of the side wall, but that air space must not be impeded. Likewise, check that both fans are operating properly while the refrigerator is on. The fans are controlled by a thermal switch mounted on the condenser fins at the back of the refrigerator. Also, verify that nothing inside the refrigerator is blocking the normal flow of air inside the box. A large cookie sheet on one shelf, for example, can disrupt the normal convection process enough to cause cooling problems. There’s an outside chance the cooling unit could be faulty, but further troubleshooting would be required to verify that. All this assumes the same problem exists during both 120-volt-AC and propane operation.
Finally, check the door seals by using the dollar bill test. Close the refrigerator doors on a dollar bill and gently tug on the bill. There should be resistance as the bill is pulled out. If not, it might be time to replace the door seals or adjust the door fitments. Be sure to check along the entire perimeter of the seals.
TEMPERATURE RESISTANCE VALUE
60 degrees F 12.1 – 13.0 kilohms
50 degrees F 15.5 – 16.5 kilohms
40 degrees F 22.5 – 23.5 kilohms
35 degrees F 24.5 – 25.5 kilohms
33 degrees F 28.5 – 29.5 kilohms
32 degrees F 30.0 – 32.0 kilohms
Add-On Services At Closing
Dear RV Doctor:
I am in the process of buying a new coach. The dealer is trying to sell me a Duratain paint, textile, leather, vinyl, awning, and undercarriage sealant for $2,000. Is this something I should have done for that price?
Mike Albrecht
Auburn, Washington
Typically, I don’t recommend any of those types of add-on products or services at the closing of a sale. It’s a common tactic to get you to agree to additional services that most likely can be obtained anytime after the sale. In some cases, it might be easier to allow the additional costs of such add-on services to be absorbed into the loan, but you might be paying interest on a service that can be purchased later, after you’ve had time to perform conscientious research on exactly what it is they’re trying to sell. I don’t condemn dealers for this; I’m just not fond of the tactic of trying to tack it onto the deal at its closing. Personally, I’d rather take my time and investigate the pros and cons of such added protection and answer questions such as: Is it really needed? Is the price reasonable?
That said, I’ve heard nothing but good comments regarding the folks at Duratain. I do have to say that in our little corner of the Northwest, extra exterior protection can be a good thing. It all boils down to whether you need it now, during the purchase of the RV, or can it wait until later. Only you can answer that.
Battery Article Redux
Dear RV Doctor:
I saved your great FMC article “The Balance of Power” (January 2012, page 46), since I knew one day I would have a use for the information. I have a “new to us” all-electric 2012 Newmar motorhome and am getting ready to install a Magnum Battery Monitor Kit so that I can keep closer tabs on our bank of eight 6-volt batteries when we are boondocking. The kit requires a shunt on the negative side to keep track of the current usage.
My question is actually rather simple. I know how to wire the bank based on your article. That will allow me to run the four equal-length negative cables to a common point before the shunt, and to the negative lines leading to the inverter and coach after the shunt. (Obviously, I will do the same for the positive side.) However, to make it all work, I need to find the “dedicated terminal connecting point” pieces you mention in the article. I have looked at some terminals, but it would seem that it would need to be more of a buss bar than separate terminals. Any suggestions? Also, should the battery ground wire to the coach be attached before or after the shunt?
John Lupomech
Houston, Texas
Pictured are a couple of different terminals as suggested by that article. Photo A shows a surface-mounted terminal. You should be able to find one with a 3/8-inch-diameter stud at any well-stocked electric supply store. You may be able to purchase different lengths so all the cables will fit on one terminal — a black one for the ground cables and a red terminal for the positive cables. Through-the-wall terminals such as that in Photo B also are available. Of course, if all else fails, a buss bar would work as well; just be sure the positive bar remains isolated from any metallic component.
I would wire the negative-to-frame ground cable before the shunt of the battery monitor. That cable also can terminate right at one of these studs rather than back to the battery bank. I’m glad you saved that article!
Refrigerator Not Working
Dear RV Doctor:
I have an Atwood HE-0601 refrigerator. All the indicator lights stay on, and the refrigerator is not working. This happened when I installed a new battery. I connected the leads wrong. The fuses are good, and the book says the issue is an open thermal switch. Where is that located?
Ruven St. Pierre Jr.
Via e-mail
Three causes can lead to all the indicator lamps being illuminated: a faulty fuse; operating the unit off-level; and an open thermal switch. If you’ve verified the fuse is good, and you haven’t run the refrigerator off-level, it’s likely an open thermal switch.
The thermal device is mounted at the boiler section of the cooling core, near the propane flue and close to where the electric heating element is installed. Check the owners manual for the locations of these components. The thermal switch has only two wires connected to it (probably white and yellow), since it’s a fairly simple thermal disc switch. I’m not 100 percent sure, but you’ll probably have to order a new switch through a retail dealer. It also might be wise to contact Atwood’s customer service line, (800) 825-4328, just to be sure.