Powertanks - how long do they last?

[WayBig]

Lots of questions tonight, whilst I'm sizing out an upgrade or two...

Pentaflex do a 7ah tank for £40, which is a lot cheaper than celestron's

(dont tell me that I can get a leisure battery, or a jump starter for less...that's for a different thread )

How long would 7ah last on, say a skywatcher auto tracker

(my rechargeable batteries in my nexstar 114slt have 2000ah total and last for at least 5h before I start to get nervous and recharge them)

Thanks for the advice...

[Supay]

I asked about powertanks the other day and was advised to just use one from Maplins. The branded astronomy ones are the same, although sometimes with extra gadgets, but sold for a lot more.

There was a good one I was linked to on Maplins the other day which was about £25 or so iirc.

[steve_bham]

Ijust use a 7ah battery as i have a seperate charge, and it easily lasts 12hours. But you need to factor in temp as it has a bit of an impact on them.

But you should easily get a full night out of it for your scope

[Bizibilder]

You can work it out - If your scope draws 1amp the 7Ah tank will last 7 hours. BUT you cannot run it like that or your tank will not last long! To be safe say 50% of that so 3.5 hours at 1 amp. A lot of scopes only use about 1/2 amp for tracking (more for fast slewing) so you are back up to about 7 hours again!

Check the literature of your mount it should tell you the current drain.

[steveangel]

Supay is absolutely right. My 5 in 1 jumpstarter from maplins cost me the grand total of £25 ad has a 17ah battery

This is considerably cheaper than the 17ah Celestron powertank priced at around £150 and does EXACTLY the same thing!

So far the longest ive used it for was 6 hours with my nexstar 6se and the readout shower over 75% charge left!

Hope this helps