Goto mount question

[Azure]

I'm thinking of getting a goto mount at some stage (have been looking at them for some months now) and was just wondering how exactly you power them? Do you use a cable or a rechargeable battery box sort of thing?

Because I've heard of both being used, and just wondered which is better, and whether it comes with the mount? I know on FLO you can buy a power cable with the mount, but the cable appears to end with either a ciggarette charger end or a 'ring tongue' end? I'm assuming you can't plug that in the house?

Forgive me if I sound a bit nooby, I'm new to all this goto stuff and don't want to make the wrong purchase

[brantuk]

I use one of these in the field : http://www.maplin.co...le-power-224871

It has two ciggy socket 12v outputs. At home I use a PSU with a ciggy socket wired in. HTH

(Most mounts come with a power cable supplied - but one or two don't)

[JamesM]

I use a leisure battery which lasts for ages and there are plenty of adaptors you can buy at Maplins and various camping shops that can help you make the connections. Whilst looking at these adaptors, it's always worth buying one that will provide you with a spare outlet in case you want to add in the future additional items like dew heaters and a laptop etc. I bought the power lead from FLO not because my mount didn't come with one (..it did) but because the connection fitting was better and the lead itself was much longer (helpful if you are sharing the power with someone else or just want the power source in a more convenient position). There are additional adaptors that will allow you to plug your mount into your home electric supply but you need to make sure that the supply is properly regulated and again Flo's long cable allows you plenty of scope when positioning your kit.

James

[sologuitarist61]

I too use a Maplins jump starter - http://www.maplin.co.uk/5-in-1-jump-starter-with-portable-power-224871

[Capricorn]

If you use a Maplins rechargeable then do not discharge the pack completely.

They are not intended for the use we make of them and if discharged them they get seriously damaged.

The problem is that when viewing we tend to continue viewing until something stops us, a power pack running flat being an obvious one.

The leisure battery type ones are good as they use a battery that is designed to run down tpo a much lower level. They cost more however.

[Carbon Brush]

As this sounds like your firsr foray in '12V in the dark' issues, perhaps a note of caution?

Mounts generally have a 'DC socket' on them. This mates with the small black plastic plug on the end of a long black cable to your battery pack (start/charge, powertank, etc). A cable just asking to be tripped over in the dark.

There is often no method of securing the plug to the mount, or at best a half hearted recomendation to twist the cable around something. After plugging into the mount, run the cable down to the tripod and secure the cable. By secure, you can use releasable cable ties, plant ties, shoelaces, etc. If you keep the battery on the floor under the tripod, keep the cable out of the way of your feet. Coil up and tie excess length. If you regularly use a setup that means the power cable is too long, then cut down and resolder the lead at the cigar plug. Or buy a shorter lead.

The DC plugs are chosen by the mount manufacturers simply because they cost pennies. Not because they are robust and good for the job. They need care.

Next the cigar type plug/socket on your powewrpack. Again a cigar plug will pull out if the cable is not secured. Also, before setting out, make sure the socket on the powerpack is a good one. Cost saving on some start/charge units can mean a low cost socket is fitted, that can give an unreliable connection. Find out at home, not in the field.

Insecure and intermittent connections will certainly mean loss of mount datum, so you have to go to the bother of a calibration routine, time/date, etc.

On some mounts, a dodgy power connection can allow the flash memory to be corrupted. The cure for this is beyond the scope of this post. Needless to say, prevention is better than cure.

As for the batteries and their care. Another big subject!

Hope this helps more than frightens! But better to make sure of everything in the light.

[skywatcher58gb]

Hi Azure

All mounts use 12V dc to drive them, and some mount manufacturers sell a seperate 230V ac to 12V dc transformer which is great if you have access to a mains socket and an extension lead. Alternatively you can buy a jump starter as described above, skywatcher also do a couple of these types of battery pack. If you buy a battery which normally have cigar sockets and intend to make your own lead with a cigar plug on one end and a small jack on the other be sure to check the polarity of the mount and wire the lead accordingly.

[Azure]

Thanks for the help guys! Much appreciated -

Yes, as you guessed, this is my first venture into powered astronomy

I was just wondering if the maplins rechargeable has a way of telling you how much charge it has left? So I could check I'm not running it flat?

Also any specific leisure batteries etc. that you guys use/reccommend?

[danielbb]

im using a 12v laptop PS. Just type '12v 2a power' into ebay.

[BargeGazer]

When I am are at a site away from home but where I can have the car nearby, I use the cigarette lighter socket in the car and a LONG lead to a socket suited to the mount or a 12 volt distribution board. If this cable is made from a good quality loudspeaker cable then distances of 10 or 20 metres are no problem. Even after several hours of GOTO power and maybe even dew and laptop supplies, a decent car battery will have used only a small percantage of its capacity and will be fully recharged on the trip home.

You will probably have to have your ignition switched onto Aux which may cause lights to come on inside the car. These will need to be trned off or covered of course.

Comments in a previous post about securing the ends of such a cable are important

[Carbon Brush]

The basics on a battery are:

Buy a pack with a large battery. Car packs generally (but not all) have about a 17 amp hour battery. This will run a goto for a few nights.

The only simple method of establishing level of charge is to measure the voltage. A multimeter is another piece of kit to buy!

Forget the red/amer/green status lights or inbuilt pack voltmeters with dubious accuracy.

Charge the battery until it reaches 13.2V to 13.8V. Do NOT go higher.

In use it will drop to 12V to 13V ish.

When well discharged you are looing at about 10.8V to 11V.

Put back on charge for at least a short time when you return inside.

Never leave a battery well discharged for any length of time.

This generic adsvice works for a small powertank battery, motobike battery, car battery, or leisure battery.