Help with a powertank for the ADV VX (6 or 8 SCT)

[scibuff]

Hi guys, so I was pretty much set on Nexstar 6 or 8 but then I had a chance to play around with the Advanced VX and 6" and 8" SCT and I was hooked. The setup is not as heavy as I thought it would be, I can easily carry everything from the car to a 100-200m distant obs place through a dirt path. 

Now, I need to get a powertank. I have the following three options at my local store:

• BTC 12V / 24 Ah for 150 EUR - link
• Celestron 7 Ah for 60 EUR
• Celestron 17 Ah for 130 EUR

I'll need the powertank to power the mount for public observations (we organize those every 2nd weekend with some folks from around) and they don't last more than 3-4 hours (so no long AP sessions).

I have a simple dew shield (no heaters), and don't currently plan on bringing a laptop along to those obs sessions so I think the only item the powertank will feed power to is the mount. Am I forgetting anything?

My questions are:

1. Would the 7Ah be enough for this purpose? Or could 7 Ah be just enough but 3-4 hours would drain it (almost) completely to the detriment of the powertank's life? 
2. How about trying the cheaper 7 Ah and if it is not enough, get a 20-50 Ah leisure battery and replace the 7 Ah with it? What would I need to make a portable powertank (5-8kg at most), e.g. where could I get a battery enclosure similar to Celestron/Skywatcher or jsut something similar with 2 or 3 12V (car cig. lighter) sockets

Thank you

[alan potts]

I have the 17A/H power tank and whilst I am sure that many others have the same type of tank there seems to be many names on the side of the same model, mines Sky-Watcher.  I can't say I have been over pleased with it, unless it is fully charged it has caused many problems with supply to my HEQ 5 Pro mount. These are mainly pointing issues with the goto system, something I found hard to believe when I posted asking advice.

If  you can afford it I would be inclined to go for a better quality battery with a Li-ion cell, I have never tried one but that would be the way I went given my time again.

When I used my mains transformer which is a quality item, I never get the same problems.

I would just point out that the power tank started to give me these issues when it was fairly new and still does but if it is full charged just before use it works well but not for that long but this is now about 4 years old and nothing lasts for ever. It may also be worth saying the mount has a high power drain but maybe not as much as the larger NEQ 6 mount, smaller mounts with lower load may well work for years. This is only my findings and may differ from others.

Alan

[Guest]

I bought this to run the VX on mains  along with this

 

As for battery power I bought two of these and they seem to provide steady power - I've not had any problems with them - life span will depend on slew frequency :-)

 

Hope that helps

 

David

[Astrosurf]

I bought this to run the VX on mains  along with this

 

As for battery power I bought two of these and they seem to provide steady power - I've not had any problems with them - life span will depend on slew frequency :-)

 

Hope that helps

 

David

I second this. I've always used these jump starter power packs and they last hours. I've been using 17ah ones and they've done well, until they no longer charge up, but they've lasted a couple of years. I've now forked out on a more expensive 20ah one which seems to be going OK. It has two car lighter (or whatever they're called!) sockets and a USB socket.

http://www.amazon.co.uk/gp/product/B00APGX6VE/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Alexxx

[scibuff]

Thank you guys!

[Vox45]

The usual comment that goes with these thread is that you should go with a deep cycle marine battery instead of a car battery. The jump starter are not meant to be discharged for a long period of time but rather provide a quick burst. Deep cycle battery can be discharged up to 80% without issues.

You can find some more info here

http://www.batterystuff.com/batteries/rv-marine/

[lensman57]

Save your money and get a deep cycle leisure battery of about 70 amps/h for the same price of a 17 amps power tank. The battery used in these is not really suitable for steady and slow dischage unlike the leisure battery.

A.G

[Guest]

I've heard about the deep cycle / marine battery option before but having used (and already bought) these jump starter packs I never really read up on the benefits.

The jump starter versions (in my link above) have worked perfectly - in addition to having a compressor and an AC converter - both of which I've never used :-) but handy if needed.

As for design - the batteries I bought are designed to jump start a car - but they won't - I tried LOL- but they run my scope, dew heaters, cameras etc - no problem

So what I'd be interested in is how much it would cost me to buy 2 similar marine batteries, a charger for them and then I guess I'd have to make something to carry them around in?

The prices I briefly looked at seemed quite a bit more than I paid for the two batteries mentioned - which are really rugged too and have lasted - so it would appear to require a great benefit to change?

David