DewBuster™ Controller Frequently Asked Questions

14" and Larger Scopes

Can the DewBuster™ controller handle a 14" SCT?
Yes, the DewBuster™ controller works well on a 14 and eliminates the need for a second controller. Efficiency is very important so be sure to place the heater strip around the aluminum tube just behind the corrector plate casting and use a dew shield. The ring terminal option is strongly recommended to reduce voltage losses.

How can a DewBuster™ controller  keep my 14" SCT from dewing up if my old controller couldn't?
The DewBuster™ controller doesn't waste battery power early in the night when it is not needed, conserving battery power. The result is higher battery voltage later in the night when you need it the most. Be sure to place the heater strip properly and use a dew shield. Also consider wrapping the heater with insulation to reduce heat loss.

Can the DewBuster™ controller produce any more heat than any other brand controller?
Not if the voltage reaching the heater is the same, but this is seldom the case. Small changes in battery voltage cause large changes in heat output (see chart below). A DewBuster™ controller with ring terminals delivers higher voltage to the heater and it does not waste energy early in the night so battery voltage will be higher late at night when it is needed the most.

How much does battery voltage affect heater wattage?
A fully charged battery will produce almost twice as much heat as a discharged battery. This is because the heat output (Watts) is equal to the square of the heater voltage divided by the heater resistance. The chart below shows the heat output curve of a typical 14" heater. The curve is plotted for when the heater is turned on (battery voltage drops when current is flowing) and assumes full battery voltage is reaching the heater. In reality, the voltage reaching the heaters is usually at least 1/2 volt lower than the battery due to voltage losses in the fuse, wiring, connectors, etc.

Can a second heater strip be added?
The C-14 heaters are marginal in heating capacity, so if the DewBuster™ controller's AUTO LED remains on constantly this tells you the heater is not applying enough heat to maintain the temperature. Before adding a second heater, try solving the problem by wrapping your heater with insulating material to improve its efficiency. A DewBuster™ controller with ring terminals can handle the extra current for a second 14" heater (plugged into second AUTO output). Since the DewBuster™ controller monitors temperature, it automatically compensates and uses no more power than a single heater, yet it can produce extra heat when needed.
 

 

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