Battery requirements

[oobydooby]

I am off to a star camp at Abernethy in a few weeks and have just got a Celestron Nexstar 4SE as a grab'n'go.  I want to buy a sealed lead acid battery because a power pack is too heavy.  All I know is that I need a 12v one, but am not sure what rating I need.  Maplins do a wide range from 20Ah down to 4Ah and I am totally confused.  I would hope the cheaper lower rated ones are fine as money is tight, but would appreciate any suggestions or help in deciding.

Many thanks

Tony (oobydooby)

[Pig]

Tony, If your mount is a rated at 1Ah and you use a battery that is rated at 20Ah to power your mount the charge in the battery will last for around 20 hours  (fully charged)

[knobby]

Pig is correct, however ... your mount will start misbehaving long before the battery rating as the voltage tends to drop as well. Probably aim for about 70% of battery rating.

Mount draws about 300 ma tracking and about 650 - 700 ma slewing from what I can remember when diy'ing a pack for mine (2500mah maplin nimh 1.2v rechargeables x 10 in 2 banks parrallel giving 5000mah) I used to get about 5 or 6 hours use but never let it go flat.

Complicated !

But food for thought .

[oobydooby]

Thanks for replies.  I have had a talk with someone who has an 8" Celestron SCT he uses on an eq mount which must be quite hefty with all the weight and so on and he uses a 7.5AH battery and he assures me that this will be adequate for my needs.  There is power at the camp so I can recharge after a nights use so hopefully all will be well.

Thanks again

Tony

[John78]

A yuasa np7-12 at £15 seems made for astronomers.

[glowjet]

Power-Sonic, both the 7Ah and 17Ah are excellent, reasonably priced, suggest you have a look at their web site for Tech info. Do remember that you will also need an appropriate charger to match the SLA battery you eventually choose, which will also add to the total cost

[oobydooby]

Went to Maplins and got a 12v 17.5AH sealed lead acid battery for about £39 and a charger for £17 , just over £56.  The battery was not charged but hooked it up to my EQ3-2 and it worked a dream.  It is now charged and will give it a test run if sky is clear tonight.

[HighHo]

I know there a bit pricey but I went with a Tracer Lithium polymer battery, its light and dont have to worry about over charging or running below certain levels. For me at least its been ideal I have the 10AH and its completely overkill for a single nights use for the mount alone I would say its 3 nights decent use (Celestron AVX).

[Staffs Oatcake]

I got myself one of these for £39 .    Absolute bargain.  And if my car won't start. I  can sort that too.  

[barrie greenwood]

I'm now on a 32Ah power caddy golf caddy battery cheap and loads of power and weight ? but I'm told that the leisure batteries are much better and lighter although more expensive

[noah4x4]

3 hours ago, HighHo said:

I know there a bit pricey but I went with a Tracer Lithium polymer battery, its light and dont have to worry about over charging or running below certain levels. For me at least its been ideal I have the 10AH and its completely overkill for a single nights use for the mount alone I would say its 3 nights decent use (Celestron AVX).

I too use a Tracer. The joy is it is compact;  will sit nicely on the SE4  tray; and its charge lasts for ages. Add a Starsense and other like accessories and you will require this level of power.

My SE4 struggles on 8 x AA batteries and "dies" in no time. My guess is other options might suffer too. That's why a Tracer  is the best option. But ensure you buy the smaller Tracer unit as the larger is not permitted on aircraft. 

[drewzilla]

Hi all. I think I'm also keen on the Sealed lead acid batteries from maplins. But I am new to all this and have no idea what sort of connector I would need to connect it to my HEQ5. Hope someone can point me in the right direction.

Cheers 

[Kardell]

Hi All,

   I was wondering is there any alternatives to these Celestron / SkyWatcher power tanks.

I would like to get one of these 17ah ones then just replace stock battery (which is crap according to some people) and put a new leisure battery in the right size, but the price is £120.

Can you replace batteries in any of these cheaper jump starters you have mentioned?

 

I am not an electrician so I don't know what to buy to make a bare leisure battery work for me especially if eventually I would consider adding a dew heater or something else to it.

 

[CSM]

I have used a Skywatcher 7Ah for the past 3 years and it has worked perfectly - it came with the scope.  What I always do is to make sure that I charge it up the next day after using it.

[Astrofriend]

I have used a lot of different batteries to my equipments, from 8x 1.5 volts AA batteries, 12 volt 17 Amph powerpack and now I use a 45Amph carbattery, still not power enough in some situations.

To get it to be more easy to handle in the dark I built a thermal isolated box to have the battery and the equipments in. You can read here how I did it:

http://astrofriend.eu/astronomy/projects/project-astro-server-and-powerunit/project-astro-server-and-powerunit.html

Now I'm on the move to build a much lower weight power box. My miniPC is the one that take a lot of power, it will be replaced with a Raspberry computer, just take some time to learn how to set it up.

 

I also have a highly portable mount, the Star Adventur, that one and the heating band I power from a USB 10 Amph powerpack:

http://astrofriend.eu/astronomy/projects/project-heating-band/project-heating-band.html#part05

 

/Lars