POWER SOURCES

The DewBuster™ Controller may be operated on a 12V Battery or 13.8 VDC Power Supply (fully charged 12V batteries measure 13.8V). All DewBuster™ Controllers have a Low Voltage 10.5V cut-off to prevent running your battery completely dead and damaging it. The newest DewBuster™ Controllers also have a High Voltage 16V cut-off to protect your heaters from burning up if your power supply should malfunction and go to 24V.

As shown above, DewBuster™ Controllers with Powerpole® connectors can switch between different pigtails to fit various power sources. I highly recommend this option so that if you change power sources you will not have to send your DewBuster™ Controller in to have the power cord changed, you simply order a pigtail to fit your new power source. For more information see my FAQ on Power Cords.

If you need help selecting a battery see my FAQ on power sources. If you are considering a PowerTank, remember that it is just a "Jump-Start" battery with extra features. If you do not need the extra features, consider a conventional Jump-Start battery available at tool or auto parts stores at much better prices. When 120 VAC is available you can power the DewBuster™ Controller while the battery is on the charger so the battery does not run down yet it prevents loss of power if the AC power is momentarily lost (use a normal charge rate, do not "Fast Charge").

The Li-Ion type Jump Start batteries are getting more popular and the prices are dropping so they are becoming a viable option for powering your telescope. Most of these units have "EC5" connectors for the 12V output so use an EC5 to cigarette socket adapter to power your DewBuster™ Controller. Beware that the mAH ratings are deceiving  because it is for the internal batteries which are not 12V. To calculate the AH rating at 12V, divide Watt-Hour (WH) by 12V. For example, an 18,000mAH Li-Ion Jump-Start unit is 67WH, which divided 12V yields only 5.6AH at 12V, so the unit is slightly less than a conventional 12V 6AH battery . The 18,000mAH was for the internal 3.7V battery (67WH / 3.7V =18AH or 18,000mAH) but at 3X the voltage we get 1/3 the AH.

When purchasing a power supply consider the following:

• 13.8VDC OUTPUT VOLTAGE - Most "12V" Power Supplies output 13.8V because that is what a fully charged battery delivers. Your heaters work better at 13.8V and will produce 1/3 more heat than at 12.0V which may be important with a big scope or when trying to burn off any dew that has already formed. Do not use a power supply that outputs 15V or higher because you risk overheating and damaging your heaters.
• DC OUTPUT AMPS - A wimpy power supply's voltage will drop each time the heaters are pulsed, so choose a power supply rated for at least twice the maximum Amps you will use (see heater manufacturer's web site for Amps). Be sure you are looking at the power supply's "Continuous" DC Output Amps (not "Peak" Amps).
• LINEAR POWER SUPPLY - "Linear" power supplies are big and heavy because they have large transformers and heavy duty regulators that can easily handle the large current swings caused by dew controllers pulsing their heaters. "Switching" power supplies are smaller, lighter, and lower priced but they sometimes have trouble smoothly regulating the voltage when the current suddenly changes. They also vary the switching cycle as current changes which can create RF noise that can interfere with your camera images. So if a Linear Power Supply is able to supply enough Amps it WILL WORK, but it is hard to predict whether a given Switching Power Supply will work so make sure you can return it if it does not work out. Another downside to switching power supplies is that they work their capacitors harder so they sometimes fail after a few years. Linear power supplies tend to last many years.
• PROTECTION FROM MOISTURE - Most Linear Power Supplies are intended for "indoor" use so you must protect them from moisture. I suggest a plastic storage container several times larger than the power supply to allow air circulation inside.  It's OK for the power supply to get warm (helps keep it dry) but you do not want it to get hot so leave a gap for warm air to escape. You can usually place the storage container upside down with the power supply resting on the lid and using the bottom of the storage container to cover the power supply.
• GFCI - To prevent electrical shock your power supply (and any other 120VAC devices) should be powered through a Ground Fault Circuit Interrupter (GFCI). Most homes have the exterior AC power outlets feeding off a GFCI from a bathroom or kitchen (press the TEST button and if the  exterior outlet loses power then it is protected by that GFCI). If you are not already protected, home supply stores carry GFCI's that plug into electrical outlets.

There are many "HAM Radio" power supplies available. Try searching the internet using keywords like "13.8 Volt 10 Amp Bench Power Supply". For customers in the USA, Pyramid makes several reliable and reasonably priced power supplies including these popular models: