Atik 383L+ light frames getting darker, power supply issue?

[kookoo_gr]

Lately i have noticed that my light frames are getting darker after each exposure at my 383L+. suspect that it may be a power supply issue but i want to be sure. I supply my camera with a 12V/45Ah battery which i have for about 5 years. At my last session i measured the voltage of the battery and it was at 12,8V at about 20C. Are there any other reasons that may cause this?

[kookoo_gr]

a few extra info. the camera runs at -10C with ambient temperature 20-15C humidity 50-60%. The lens on my scope has not fogged up from humidity. The light frames are getting darker during a photo session 

[Lex]

Hi,

AFAIK batteries drop current after a certain time. You get the best results with a regulated power supply.
I use a 13,8V 5A constant power supply for my cameras and my mount. A good point with a power supply is that it is "earthing" the equipment so that static energy can be discharged.
For me this is one of the possible causes of your problem...

Best

[jolo]

Hello,

It seems to be voltage drop issue. As I found out in my camera (and some other users as well) when voltage drops below 12V hot pixels amount rises very much. The battery voltage can drop uner 12V quite fast (under load) so it can be that in your frames there are many hot pixels and then if you use any kind of auto stretch in the software it may appear darker. I described this in my blog: http://astrojolo.blogspot.com/2013/09/atik-power-hunger.html

Lukasz

[kookoo_gr]

I saw your blog and i would like to ask if the step up board pic you have is a sample or do you actually use it for powering the camera. Maxim showed me that the consumption for -10C was at 50%

Here are two pics (not calibrated) form my latest session, the first and the sixth (last) 1200 sec bin 1x1 Ha. I measured the darkest part of the image near the top left corner and at the center and the values were close to each other.

http://stargazerslounge.com/uploads/monthly_10_2013/post-4387-0-91597000-1382880489.jpg
http://stargazerslounge.com/uploads/monthly_10_2013/post-4387-0-83524000-1382880499.jpg

P.S. an off topic question. I saw the HEQ5 belt you made and i would like to know if it has improved your imaging since i have not seen any photos with this mod from the time the maker started developing it.

[jolo]

I use this board to power my camera in field using 12V battery. I can regulate output voltage to 13.5V and then it keeps it for all time till battery is depleted.
This belt mod I bought in Rowan Astronomy - it is really well done. For the imaging - it has been improved in terms of peak errors - I often had the peaks over 2" before. After the mod has been applied they disappeared, but actual RMS value of guiding has not improved much - it is still about 0.4-0.8" depending on seeing.