My batteries don’t charge when connected to shoreline power. How can I test my converter?

Dear Dave,
My converter does not appear to be working. My batteries are not being charged when plugged into shoreline power. How can I test/check to verify an inoperative converter on my Airstream? —Jay, 2020 Airstream Classic 33

Dear Jay,
According to the Airstream technical library, they use either a WFCO WF 9855LiS converter, either integrated or deck-mounted, or a Progressive Dynamics 4045 LCSV integrated only. The integrated models of either brand mean the converter is part of the distribution center, such as this model. The converter is to the right side, where you see the vents, and has an internal fan.

The WFCO deck-mounted model is a separate converter/charger that would be mounted somewhere hidden, like under the bed or under cabinetry, to hide some of the fan noise and heat.

All models take 120-volt power from the shoreline cord either by plugging into a campground source or by using the generator and converting that power to 12-volt DC power to charge the battery or batteries.

Your unit would have WFCO deck-mounted converter

According to the site, your unit came standard with 50-amp service and would have the WFCO deck-mounted unit. All converters utilize a 3-stage charging procedure that starts with a bulk charge of 14.4 volts, known as the quick charge/bulk stage. It then drops to 13.6 volts, known as the nominal charge/absorption stage. Once the batteries reach 12.6 volts they are fully charged, and the converter drops to 13.2 volts, known as the trickle charge/float stage. The bulk stage charge can last up to four hours.

Your WFCO can also be configured to charge Lithium Iron Phosphate (LiFePO4) batteries, which require a 14.6-volt charge for a specific amount of time, typically 1.5–2 hours, then go into a float charge of 13.6 volts. A 14-gauge jumper wire is required for your converter to change the charging profile. On the back side of the converter, there are two 35-amp automotive fuses when it is in the FLA charge mode. If it is set up for lithium, there will be an electrical plug labeled “Lithium Switch” and the jumper wire.

Test your converter

To test your converter, start by unplugging the unit from shoreline power and, without the generator running, use a multimeter to test the batteries. If you have the original AGM batteries, they should be 12.6 volts if fully charged. Anything lower will indicate a depleted battery. Depending on that state of charge (SOC), the converter should kick into a higher voltage when plugged in.

Next, plug the shoreline cord into a 30-amp power source and check the voltage going to the batteries. It should be at least 13.2 volts if the batteries are fully charged and higher, depending on the SOC such as 13.6 volts or even 14.4 volts. If you disconnect your batteries from the system, the converter should recognize the low or lack of voltage and provide a bulk charge of 14.4 volts. This will tell you if the converter is putting out the correct charge procedure.

Verify shoreline power

One other item to look at is the shoreline power coming into the distribution center and the other 120-volt components that might be running. From what I can tell from the information on the website, your unit has a 50-amp service. However, if you are connected to a 30-amp outlet or even worse, a 20-amp residential outlet that might be at your home, you could be starving the converter for power.

I remember back in the late 1980s, when working at Winnebago, we had a unit called the Elandan, which had a 30-amp power center and converter. When connected to shoreline power and running the roof air conditioner and other 120-volt appliances, the batteries would go dead. After much research, it was determined there was not enough power for the converter to charge at full capacity.

If you are plugged into a residential 20-amp outlet, use the multimeter to determine the charge going to the batteries. You can shut off all circuit breakers at the distribution center except the main and the converter to verify there is 100% power going to the converter and what the charge is.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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