12 volt current booster?

My Kendrick "smart" Dew Controller "DigiFire 10" likes to work at 13.2 volts, and works fine when using my Radio Shack 110V, 3 amp, 12V power supply, which supplies a steady 13.2 volts.
However for field use, my dedicated 80 amp hr. 12V gel battery generally operates at around 12.8 volts and the Dew Controller flashes "Low Current Warning" and won't supply power to the heater coils when drawing 12.8 volts.
Can I use something like the Lacey 12 volt to 18 volt converter or a similar light weight unit that boosts battery current voltage to over 13V? Any link to any type voltage booster that operates off a standard car battery, would be appreciated.
I've tried using the 3 amp inverter I use with my computer, between the battery and the Dew Controller, and the Kendrick wouldn't work at all with that. (I'm using six heater coils on the "DigiFire 10.")

>>>>However for field use, my dedicated 80 amp hr. 12V gel battery generally operates at around 12.8 volts and the Dew Controller flashes "Low Current Warning" and won't supply power to the heater coils when drawing 12.8 volts.
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Note that it does not say "Low Voltage Warning" but rather "Low Current Warning." As someone else pointed out, this suggests there is some sort of high resistance somewhere in the current path.

Does the controller work properly if your gel cell (not the with the power supply) is topped up to 13.2 volts?? If it does, then I am with Floyd that something is misadjusted inside the controller.

If it does not work with the voltage topped up to 13.2 volts, then I would look for a less than perfect connection or undersized wiring between the gel cell and the controller.

Best way to check for voltage drops in the current path is with a DVM (Digital Volt Meter) and measuring the voltage at various points while the controller is hooked up and turned on. Sometimes an old fashioned needle meter works better because of the quicker response.

I would also give Kendrick a call and discuss it with them. I would be surprised if the controller required 13.2 volts to operate, batteries will have surface charge that puts them there but when that disappears quickly.

Jon