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Dewbands & CCD on same 12V source?


Grinde
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Hi guys

I'm building a portable battery-box for my imaging setup, & have some questions.

The box contains a 12V 95Ah deep cycle marine battery, with charger-socket on the outside, so I don't even have to open the case to charge it. and i've added six 12V sockets on the outside, all with seperate fuses.

The stuff I need 12V power for is:

Mount (EQ6)

Dewbands (1-2 bands, depending on setup)

Laptop (Asus EEE 1005HA)

Camera (QSI583wsg or Canon 50D)

Robofocus

I also got a lil' space left in the portable box, so I can fit a small 12V 7Ah battery too, to power the 6th 12V socket seperately, if it turns out that I need it.

So the question: Is it necessary to run the CCD & Dewheaters on seperate batteries..? I think I've read something about the dewheaters (& also laptops) interfering with the CCD if used with the same 12V battery. And if so, does it damage the ccd, or just add extra noise?

& if I have to run 'em on seperate batteries, would it be best to run the ccd on the 12V 7Ah battery, or the dewbands?

Or will I need an even bigger battery to run either of 'em seperately?

Thanks!

Jonas

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I don't think you should have any problem from a common 12v DC Supply feeding all your equipment, as long as the capacity is sufficient to sustain it. The output is smooth, and there shouldn't be any interference. Don't have the charger connected whilst the battery is in use though.

What are your Dew straps rated at, and are they on a controller of some sort?

Ron.

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I don't think you should have any problem from a common 12v DC Supply feeding all your equipment, as long as the capacity is sufficient to sustain it. The output is smooth, and there shouldn't be any interference. Don't have the charger connected whilst the battery is in use though.

What are your Dew straps rated at, and are they on a controller of some sort?

Ron.

The straps are rated at:

for the 190MN- 20W 1.6A , + it's ST80 guidetube, 11W 0.9A

(might ditch the ST80 if my OAG will be doing it's job)

or

for the FSQ- 15W 1.2A

The controller is a Hitech Astro 4channel dewcontroller (top of the page)

No problem at all - I run my mount, dew bands, CCD, CCD Peltier/Fan, GPS etc etc etc all from the same 12v supply with no problems.

Exactly what I was hoping to hear, then I might even be able to store some cables & gadgets in the same compartment! What kind of battery do you have, & how long does it last, running everything?

A battery while unregulated acts like a capacitor in the circuit and smooths any interference generated on the power lines so won't interfer with the CCD.

Dave...

Ah, so that's how it works, thanks for the heads up! Is it another story if you run the same gear from 220V AC with AC/DC:headbang:-converter?

Thanks for the help guys, back to cutting cables & soldering!

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As most dew heaters are pulse width modulated I would keep it separate, although the interference may be small it's a bit of an unknown quantity and noise is the enemy of the astrophotographer.

Regards

Kevin

Ahrg, I'm trying to get rid of all the 'maybes' , so I guess it'll be seperate then... Would you recommend giving the dewbands or the ccd it's own smaller battery? & approx. how much capacity would I need to run either the ccd or dewbands for a whole night of imaging? (hopefully)

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What's the max current of the dew bands? If it's no more than 1A then put the dewbands on the smaller battery and everything else on the larger battery. This would give you enough for a 6-7 hour run and even if the dew bands run out you will be able to carry on for a while until dew sets in or you could swap batteries without affecting the rest of the kit.

If you do decide to use one battery only I would recommend having seperate 0V to each item and creating a star point at the battery ground terminal.

Regards

Kevin

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What's the max current of the dew bands? If it's no more than 1A then put the dewbands on the smaller battery and everything else on the larger battery. This would give you enough for a 6-7 hour run and even if the dew bands run out you will be able to carry on for a while until dew sets in or you could swap batteries without affecting the rest of the kit.

If you do decide to use one battery only I would recommend having seperate 0V to each item and creating a star point at the battery ground terminal.

Regards

Kevin

Here's the project, just completed

Depending on which scope I'm using, the bands are rated at either 1.9A or 1.2A.

I just found out I got two 12V 7Ah batteries, so I'll run the dewbands with them, replacing if running out.

& I'm also curios about running a test to compare the amount of

noise added by running it all on the same battery... Will darks be enough for that kind of test, you think?

Thanks alot for the advice on the 0V, unfortunately I had already connected the wires when I read it, but I'm thinking about rewiring after I buy some more 0V cable, since I ran out.

Best Regards

Jonas

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