Doc Posted July 16, 2015 Share Posted July 16, 2015 Time to sort out dew control on my new scope as winter is nearly here. The whole point of my scope set up is that it's a quick grab and go set up, so I'm staying away from large batteries, wires etc. I have found the following website called Tech2000 and they have a product called Zap-On. http://www.tech2000astronomy.com/zap/ I know you shouldn't believe everything that is wrote but according to their website, it runs from one 9v battery. They quote 10 nights on one battery. Now what could be simpler then wrapping a dew strip around your tube and just connecting one little 9v battery. No wires, No dew controller. I would get three, one for the tube, one for the finder and one for 1.25" eyepieces. The finder and the eyepiece I would splice the wire and use one battery. All I have to do is carry a few spares or buy rechargeable batteries and charger. Any comments. Link to comment Share on other sites More sharing options...
M. Posted July 16, 2015 Share Posted July 16, 2015 I guess it's worth a shot, if it ain't too expensive. Link to comment Share on other sites More sharing options...
Doc Posted July 16, 2015 Author Share Posted July 16, 2015 Just hoping someone who knows about electrics can work out if these heaters will get hot enough on just a single 9v battery. Link to comment Share on other sites More sharing options...
Tweedledee Posted July 16, 2015 Share Posted July 16, 2015 I'm sure they will get hot enough, but I'd be surprised if the batteries last as long as they claim. However they look ideal for you Mick, to avoid trailing wires. Looks good and neat Link to comment Share on other sites More sharing options...
M. Posted July 16, 2015 Share Posted July 16, 2015 I don't think heat is the real issue, but more endurance of the battery. It's possible to get extreme temperatures by using resistors in series off even a AAA battery. Link to comment Share on other sites More sharing options...
Doc Posted July 16, 2015 Author Share Posted July 16, 2015 I agree I doubt very much if one battery will last 10 hours. As there is no dew controller I would imagine it's on full pelt all the time until the power drains to nil. Link to comment Share on other sites More sharing options...
Smithysteve Posted July 16, 2015 Share Posted July 16, 2015 Hi Mick, I would consider using bog standard heater strips with a bespoke rechargeable lithium battery. You could do everything they can do with one battery ( and a few wires :-) ) Tweedledee can advise you on the lithium battery, he already has one. I have had a look at the web site and yes it all looks appealing, but in practice you would either get through a lot of batteries or forever be charging up re- chargeable ones (and re-charging these types of bats is quite inefficient) The heater straps are resistive loads and they are converting current into heat, so they will use a fair amount of juice. That's why resistive element electric fires take about 2 kilowatts +, but electronic equipment only takes a few watts... If you decided to put a 12volt supply onto same 9 volt straps as they advertise you can, then you would increase the current flow by about 33%, ( amps = volts/Resistance ) so they would be 33% warmer! Would that be good? They do not seem to have any control or on/off switches so you may have to de- couple batts when finished... I could go on... If you are still tempted then go for a very small one, say for your eyepiece, and see how you go. 😄👠Link to comment Share on other sites More sharing options...
M. Posted July 16, 2015 Share Posted July 16, 2015 I think surface area and thermal conductivity is most important here, wouldn't a 2" thick band that wraps around the near 4.7" aperture ? total approx area of 0.14m^2 I'd liken this to a small heat mat that's used for keeping spiders, based on this logic I'd say it would most likey work. I could be wrong though, it happens often lol Link to comment Share on other sites More sharing options...
Smithysteve Posted July 16, 2015 Share Posted July 16, 2015 I agree I doubt very much if one battery will last 10 hours. As there is no dew controller I would imagine it's on full pelt all the time until the power drains to nil. Connect a large (or small) dew heater across your nice big car battery and it will flatten it.... It's just a load that turns the power in your battery to heat... Only good thing is you are limiting the current flow using a tiny 9v battery (because of the tiny ampere /hours output), so they would be safer in that respect ... Link to comment Share on other sites More sharing options...
Smithysteve Posted July 16, 2015 Share Posted July 16, 2015 I agree I doubt very much if one battery will last 10 hours. As there is no dew controller I would imagine it's on full pelt all the time until the power drains to nil. It could last 10 hours but the output would decline over the 10 hours so it would become more and more inefficient as time went on... Link to comment Share on other sites More sharing options...
Doc Posted July 16, 2015 Author Share Posted July 16, 2015 I understand. It's basically a standard dew strip with a 9v connector on the end. The strip will get hot and drain the battery until it's empty and then you change the battery for a new one. Problem is it will not be a constant heat until the battery is drained it will taper of as the battery gets low. Will check out lithium batteries Steve. Link to comment Share on other sites More sharing options...
Tweedledee Posted July 16, 2015 Share Posted July 16, 2015 (edited) I have the 22Ah Lithium Tracer battery, but don't think you'll need anything that powerful. They apparently have a flat discharge rate and keep their voltage nicely, work perfectly at sub zero temperatures, and are very small and lightweight for their power output. http://www.firstlightoptics.com/batteries-powerpacks.html Edited July 16, 2015 by Tweedledee Link to comment Share on other sites More sharing options...
BAZ Posted July 16, 2015 Share Posted July 16, 2015 Not forgetting that a batteries performance is badly affected by cold. It increases the internal resistance, and can cut the expected run time in half. Even sat on the dew band, I would expect a loss in performance. Proof would be seeing how it coped on a minus four night. The funny thing is, I really want it to work, because it's such a good idea. Link to comment Share on other sites More sharing options...
Doc Posted July 16, 2015 Author Share Posted July 16, 2015 I agree it's a brilliant idea Baz. Even if the battery lasts just 3 hours instead of 10 hours then that only equates to 3 changes on a 9 hour night and how many times do we have a night like that. All I then have to do is recharge the batteries when I get home. No more wires, No more leisure battery, No more dew controller. As Steve says I might try one and see how it goes if it lasts 3 hours then that's a good deal. Link to comment Share on other sites More sharing options...
Tweedledee Posted July 16, 2015 Share Posted July 16, 2015 I'd be worried that as it is not adjustable, it could be putting too much heat in causing temporary image distortions. Also that the battery is likely to die without you realising until it dews up just when you are in the middle of that exciting observation. But still a neat idea if it does the job. Link to comment Share on other sites More sharing options...
Doc Posted July 16, 2015 Author Share Posted July 16, 2015 I understand your concerns Pete. I have terrible OCD when it comes to wires. In fact I'm also OCD on central heating and water pipes, I've hidden them all in the walls and floor when I done up the house, looks neat but I'm dreading it if one bursts. Link to comment Share on other sites More sharing options...
Tweedledee Posted July 16, 2015 Share Posted July 16, 2015 I see Mick. Probably the ideal system for you then Link to comment Share on other sites More sharing options...
+RonC Posted July 16, 2015 Share Posted July 16, 2015 You can also get rechargeable 9v batteries don't forget!! Ron Link to comment Share on other sites More sharing options...
M. Posted July 16, 2015 Share Posted July 16, 2015 I understand your concerns Pete. I have terrible OCD when it comes to wires. In fact I'm also OCD on central heating and water pipes, I've hidden them all in the walls and floor when I done up the house, looks neat but I'm dreading it if one bursts. Out of sight out of mind My dad had a similar obsession, he never liked wasting stuff and was overly excited about using expanding foam (everywhere lol) . I really feel for that family that recent bought our old house lol Link to comment Share on other sites More sharing options...
M. Posted July 16, 2015 Share Posted July 16, 2015 You could also buy a solar charger of sorts too, and charge a few batteries at no extra cost. I would maybe velcro a few 9v batts on the strap and then that way you can just switch between batteries with no impact on your stargazing. Doc 1 Link to comment Share on other sites More sharing options...
Doc Posted July 17, 2015 Author Share Posted July 17, 2015 You could also buy a solar charger of sorts too, and charge a few batteries at no extra cost. I would maybe velcro a few 9v batts on the strap and then that way you can just switch between batteries with no impact on your stargazing. Link to comment Share on other sites More sharing options...
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