Dew heater questions

[Ric]

Hi all,

I've just started using a Kendrick dew heater this year, I've always had a large dew shield so it wasn't a big priority.

Not having used one before I have a few questions.

1. I'm using it with a 900 amp jump starter/power pak, the dew heater is the only thing being used of it but it seems to drain the pak in around 5 - 6 hours. Is that normal or should I expect more? or should I look for a stronger power pak.

2. While the corrector remains clear and dew free I don't feel any warmth in the heater I usually have the heater at about 60 - 70%.
Should I feel any warmth or is it only gently warming the corrector to a few degree's above air temp and therefore not really noticeable.

All the best

[MattT]

Ric,
I use the 4 channel heater with a 17amp hour battery and it lasts all of two nights with goto's on an HEQ5pro hours with the heaters going flat out.
About 8 hours worth I reckon, so yours sounds about right. I feel the heat so it's probably a bit too much but nice on cold fingers.
Matt

[Ric]

Cheers Matthew

[pgc hunter]

I use a 900 amp jumpstarter with a 4-channel 1000 Oaks heater which last a good 2 nights on one charge. I feel a lot of warmth in the strips at only 40-50% power but my case only about 30% is necessary to keep things dew free in all but the worst conditions. The heaters don't operate constantly, but rather in "pulses" or "waves". In other words, the heater will warm up, then switch off for a short period, then when temp starts dropping it will switch on again. I don't know if other brands do this. I'm guessing it works this way to save battery life.

5-6 seems like a pretty short time to drain a jumpstarter just from using dew heaters.

[Larryp (Laurie)]

Ric, how old is the battery in your jump-starter? Perhaps the battery isn't in the best condition. Sometimes even new ones are not great, and I think the quality of battery used in jump-starters is not the best, anyway.

[Ric]

Hi Sab / Laurie

Thanks for the info, by the sounds of it mine might be getting a bit old.

It's about 4 or 5 years old and has spent most of it's life pumping up tires.

I bought it from Super Cheap Auto so it wasn't probably of the highest quality to start with.

[Larryp (Laurie)]

Originally Posted by Ric

Hi Sab / Laurie

Thanks for the info, by the sounds of it mine might be getting a bit old.

It's about 4 or 5 years old and has spent most of it's life pumping up tires.

I bought it from Super Cheap Auto so it wasn't probably of the highest quality to start with.

Ric, you can probably replace the battery without replacing the whole jump-starter. If you can, I would suggest replacing it with an AGM type deep cycle battery-you can buy them fairly cheaply on Ebay.

[Steffen]

Originally Posted by Ric

Should I feel any warmth or is it only gently warming the corrector to a few degree's above air temp and therefore not really noticeable.

I'm wary of that, too, I don't think it's a good idea to introduce too much heat. If the optics get warm then you could get all sorts of other issues like tube currents, mirrors going out of shape etc. All you need is to keep the surfaces above the dew point.

Not having a temperature sensor or intelligent dew controller I try to manually adjust the heaters to be cold enough not to feel warm and just warm enough to prevent dewing.

Cheers
Steffen.

[roughy (Mark)]

I use an AC adaptor from Jaycay on a Digifire 10 Output rated at 12V, 7.5amps. About $30.

[Ric]

Hi Laurie

The powerpak is a sealed unit, I think it would be just as easy to simply buy a new dedicated one.

Hi Steffen

I'm always wary of that and try not to go above approx 60%. I also have the thought that the corrector plate might crack and then I would really be up the creek without a paddle.