Dew Heater tapes - Power consumption?

[Alveprinsen]

Ok, so I've got an order from FLO on the way that will hopefully eliminate my dew problems.

However, I have no experience with these heater tapes, and it would be helpful if someone with experience could give me an idea of what kind of power consumption I will most likely be looking at.

I will be using a HitecAstro four channel four port Dew Controller along with two heater tapes sized for 4" telescopes.

I plan on plugging this thing into a 9Ah battery I got, but I fear that might not be enough juice? With warmth-producing stuff I just naturally assume that they require quite a bit of power...

Hope some of you with electric dew shields and heater straps are able to give me a few examples.

Sincerely, Alveprinsen.

[Carl Reade]

Hi, This may help also 4" strips should be around 0.9 Amp at 100%. Cheers Carl

Q: My heater setup indicates (as an example) I need a 6 amp power supply. Do the heaters draw 6 amps all the time?

A: Only when the controller has pulsed on. For example if you have a controller set to operate the outputs at 40% it will draw 6 amps 40% of the time. The other 60% of the time the draw will be zero. Averaged out it will be drawing only 2.4 amps per hour. With temperature or dewpoint sensing modes, the heaters will draw their full amperage rating but only when switched on by the controller.

Q: What size battery should I use?

A: That will depend on the size of the heaters you are using. See this chart to help you decide. Bear in mind that these figures represent the amp hour draw at 100%. The actual amp draw is a factor of your controller settings (1% to 100% depending on controller in use and setting chosen).

Q: What happens if my battery is low?

A: All our controllers all have built in low voltage cut-off control. When your battery gets to a certain voltage, the controllers will shut down, saving your battery from being too deeply discharged.

Q: How long will my battery last?

A: This will depend on three things,

1. The amp hour rating of your battery.
2. The amp hour rating of your heater (see chart).
3. The setting of your controller.

The formula is: battery amp hour rating / (heater amp hour rating x % of controller setting) x.8.