Gonna keep you lot busy, another question.

[Simon E]

I probably know the answer to this question.

I have a spare 520amp car battery lying around. If it powers a EQ5 mount, couple of dew heaters etc etc. Will it last all night?

I am assuming a big fat yes, no harm in asking though, as i'm sure others on here use the things.

Thanks Si

[JohnP]

Hi Simon, I think the 520A you refer to is the short term cranking capacity in Amps - i.e. how many Amps it can provide instantaneously for a very short period of time in order to turn over a big metal engine dipped in thick oil etc.. What you need to look at is the Ahr capacity of the battery (Amp Hour) - this give an indication of how many Amps it can provide continuously for an Hour - your standard 12V car battery is around 85Ahr.. i.e it can provide 85Ahr for one hour or 170A for 30mins or 8.5A for 10 hours.. etc. these are all theoretical Maximum - in reality with cold temps etc. age you are probably looking at a much less then these maximum's. Assuming your mount draws 1A (when slewing), Dew heaters (depending on size) can easily be 2 or 3 A, a laptop will easily draw 4 or 5 A + cooled camera 2A - so you could be looking at needing 9 or 10A from the 12V (if you power everying) - based on that an average car battery (85Ahr - in reality say 60A) might last 5 hours or so if in peak condition... If I'm  at a remote location in field I would recommend using at least a coulpe of car batts.

Hope that helps. John

PS - I seem to remember Mac doing a really good write up on use of batteries sometime in the past..

[Simon E]

Thanks for that John, Just looked at the battery and it delivers 60AH, so may have to get another then. It is pretty new and only a year or so old.

Thanks Simon

[Rick]

Check out the infamous Leisure Batteries thread for information (if not for actual shopping links, as it's rather old now)...

Edit: Actually, for better and more recent information it's probably worth checking this thread --> http://forum.orpington-astronomy.org.uk/index.php?topic=8445.0

[Simon E]

Hi Rick, I was checking out ebay as you wrote your post.

I can get a 110ah leisure battery for £50, so I think that will be the way to go, with my 60ah as a spare.

Cheers si

[Mac]

ahh the good old infamous Leisure Batteries thread, whatever happen to that 

Mac

[JohnP]

Just looked at the battery and it delivers 60AH

Yep - defo not enough for a full night with everything running...

Also might be worth considering running your mount off the battery you already have & everything else off the new one you are looking to get. The only reason I say that is that potentially dew heaters etc. switching ON/ Off might cause glitches that could screw up the mount/ or cause it to 'stack' Believe me the last thing you want to happen in the middle of the night is loose power to the mount.. especially if you are in the middle of imaging.

John