Roughly how long do you get out of a 7AH power tank with a Nexstar 6SE ?

[bobafett]

Seems to be a huge price difference between the 7AH and 17AH power tanks so I was wondering on average how long the 7AH lasts off a single charge ?

[brantuk]

Scopes tend to draw 1-2Amps so in theory about 3.5 hrs - A 17Ah tank should last 8.5. But then if you attach dew heaters and cameras this will come down considerably. Also - the tracking gets less effective as it drains below half it's charge. I got the 17Ah and when I accidentally flattened the battery, replaced it with a 20Ah battery. Keep them well topped up if you get one - or go for a deep cycle leisure battery instead. There are other options like 5A psu's if you use campsite elec hookup. Hope that helps

[Glider]

Halfords, Powering PRO120, 40Ah, used in winter for 6-8hrs at a time, freezing temperatures and never got below 75% on the indicator LEDS.

Even if I don't use it I give it a few hours charge once a week.

[acey]

You never get 100% efficiency, so you won't get 3.5 hours of 2A current from a 7Ah source. Maybe only half that. And a battery drained right down before recharging will have a shorter lifetime than one that only gets half drained. So it's worth paying more for 17Ah.

[bobafett]

Right OK just checked the spec sheet in my Nexstar 6SE manual and it says it's 750mA so mathematically thats 7Ah / .75A = 9.33 Hours

Then factoring in the "maybe only half" efficiency quoted above then that's still over 4 and 1/2 hours right ? I think that would be plenty for me. I think.

That said, if I add a dew shield to my set-up at some point, it looks as though they draw around 1.5 - 2 amps

[Psychobilly]

A Passive dew shield wont draw any power one of the ones with a dew band built in or seperate dew bands will...

Peter...

[Glider]

4 hours will go very quickly when you are having fun. I'd work on the basis that there's never enough time and money to do it properly, but there's always the time and money to do it twice. Get the biggest one you can!

[Sparrow]

From memory I think the 6SE draws 750maH or .75amps. On this basis and the fact that you should never drain a power tank more than 50%, it would give you a theoretical maximum of 4 1/2 hours. Go for atleast a 17aH power tank - that's what I've got and it used to run all evening with my 6SE and dew heaters running from it.

[brantuk]

If you get 4 hrs of good seeing - then let me know where you are and I'll come join you lol I've barely had a a good session over two hours in the last 3 months.

[steve_bham]

i used the 7ah celestron one on a nexstar 6se and easily got 5-6 hours out of it no problem.

[bobafett]

i used the 7ah celestron one on a nexstar 6se and easily got 5-6 hours out of it no problem.

That's exactly what I wanted to hear - thanks

[Demonperformer]

Maplins do a 17Ah one that is cheaper than a lot of 'astronomical' 7Ah ones. I think they are currently about £35, but they frequently do a reduction to about £25, which is what I paid. Never run out during a session yet.

[acey]

I got my 17Ah jump starter from Woolworths (remember them?) for about £25. Saw the same thing in Maplin the other day on offer for about £20. All I use mine for is powering a 12V hair dryer (and occasionally starting the car).

[bobafett]

Maplins do a 17Ah one that is cheaper than a lot of 'astronomical' 7Ah ones. I think they are currently about £35, but they frequently do a reduction to about £25, which is what I paid. Never run out during a session yet.

Do you have to make up a power cord to go on these then I take it ?

[Demonperformer]

Standard cord with cigarette plug on one end and power tip on the other. A (short) one was included with the power tank, but got a longer one from S'n'S astroboot for £1.

[bobafett]

I assumed you'd get a cord with the astronomy power tank ones but I was refering to these maplin ones ?

[themos]

The Maplin unit comes with a cigar lighter socket on its side.

[bobafett]

OK thanks

[Doc]

I would get a leisure battery of at least 85 Ah and connect a three way cigarette connector to it. One for your mount, one for your dew controller and a spare one for camera etc.

[robhal9000]

Hi,

One advantage of the astro powertanks is they have 2 cig sockets rather than just the one on the maplins.

Re cables. I have read you should never use a cable that is not specific for your brand of scope. That, I think, is why they do both celestron and skywatcher cables at FLO. The SW powertanks come with a SW cable.

I have both 7AH and 17AH.The 7AH ran my 6se with two dew strips for the whole evening.

[brbelly]

i have my own business repairing mobility scooters. i know they use a 24 volt system, but 2 12 amp/h hour batteries on a small scooter can scoot around most of the day on one charge. so a 7 amp/h bat will run a scope using 750 ma for a good all night session.

also scooter motors use a lot more amps.