I run the camera off DC and the laptop off an inverter. Another option is a battery dedicated to the laptop, which is a power hog. I've thought about a portable generator, which is more versatile, but also is not always permitted at the star parties depending on how dry the area is and Forest Service rules.

--- In ap-gto@yahoogroups.com, "observe_m13" <JunkMailGoesHere@> wrote:

What you require is to figure out what your actual energy consumption is. Knowing Watts = Amps * Volts

1) The SBIG camera (Peltier coolers swill power), what is its rating in Watts? It will likely be using a significant portion of that (80-90%) constantly depending on temperature. If it is running off an AC inverter inverter add at another 20%.
2) laptop (they swill power too but can be adjusted somewhat to use less by turning off the screen and running in a low power cpu mode. Do not confuse this with the overall Windows style machine settings of low power mode as that may also turn off hard disks, USB ports and other items which may require constant power to keep the imaging and tracking software working properly. You will have to manually configure a usable low power mode and then measure the consumption. Problem with laptops is that they can run off the internal battery for a while and then when it is empty it wants to be plugged in. This really costs power as it not only has to run the entire laptop, it has to run the charging circuitry to recharge the battery. Oh, if it too is running off the 110VAC inverter add another 20% as well.
3) Mach1GTO - it all depends on how much you are slewing. It can use from a negligible amount of less than a Watt to around 15 Watts if you are slewing constantly.
4) Focuser - barely noticeable power use once it has run through its focus routines.

This is really a SWAG since I have no idea about your actual equipment, but I'd expect you will be pulling down a minimum of 60Watts (5Amps * 12VDC nominal) and are actually going to be using even more.

Once you have a firm grasp of the total energy required you will have an idea of what capacity of battery you will be able to use and how much energy you have to put back into the battery. While you can run at a deficit for a period of time, overall you will likely have to put back about 75% of the energy used daily and small inexpensive solar arrays won't do at all. Even moderate sized moderate priced ones of 2 to 3 or so square feet only put out about 20 Watts maximum (~1.2A @ ~16VDC) in intense direct sunlight. The only way around this is several solar arrays as described (and don't forget the proper battery charging circuitry), several more batteries to cover the expected energy required, or a source of reliable AC power.

Anyway, this is all just guesswork until you come up with some firm numbers for actual consumption.




--- In ap-gto@yahoogroups.com, "Wayne" <wayneh9026@> wrote:

I will be at a couple 5-night-long star parties running Mach1 mount, focuser, SBIG camera and laptop from about an 80 amp-hour AGM battery. I expect I can get at least 2-3 nights from the battery but not sure about 5. Any recommendations from the gallery on a reasonable solar charger to get me through the week?

Thanks!

Wayne