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Power source for synscan alt AZ mount.


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I am very ignorant when it comes to things electronic. My basic question is.....is a Meade type portable battery power source pack suitable for a skywatcher synscan alt  AZ mount?.....the synscan instructions mention odd sounding amps etc and I don't want to blow a gasket in my mount ! ....all advice gratefully received. Andy  

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Which mount do you have?

For info, my Virtuoso and the HEQ5 use the same power supplies - one is a Maplin XM21X:

maplin_xm21x_dc_power_supply_front.JPG

The other is an old car battery which doesn't have enough amps any more to start a car, but plenty for telescopes!

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I Have just bought a sealed lead acid 12v 12ah battery for a few pounds and its runs the mount a treat, used it about 12 times now for at least 2hour  sessions and it has barely used any power when checked with my multimeter and small enough to be portable, check screwfix and toolstation.

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For field usage you should buy a car 12V 40Ah lead acid battery, this will have plenty of juice to power your mount. Some people may advice you to buy car jump starters which are a bit lighter than a standard lead acid but it will have less energy, it may be fine for your usage if you plan only to power the mount from it, but if you want to power mount, laptop, USB hubs, heaters and other kind of stuff then *even* the 40Ah lead acid will be giving you around 6h of autonomy. This autonomy will decrease with the outside temperature, the colder it gets the less runtime your battery will have.

For indoor usage something like this will work great.

https://www.banggood.com/12V-10A-120W-Switching-Power-Supply-For-LED-Strip-Hot-AC-110-220V-p-69415.html

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Thanks guys....awesome stuff....so the 'tip positive' on the power requirements is nothing to bother with? I don't know what it means.....however it looks like the car battery is the way to go ?

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"Tip positive" just means that you'll need to connect the positive pole of the battery to the "tip" of the power plug; in this case the tip of a female power plug is it's inside. Sleeve will connect to ground.

51141dfdce395fe801000002.jpg.c2cfe32969c3f6d724316ad6506868b7.jpg

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Your mount requires very little power; 8xAA batteries used to drive mine for several nights. a 12amp houe battery will be plenty; see if you can find an old motorbike battery or the like for £5-£10, then you'll need to do some basic DIY stuff and get a trickle charger to keep it topped up, like this: https://www.amazon.co.uk/Streetwize-Motorcycle-Automatic-Trickle-Batteries/dp/B0012U5BO2

Else get a car jump starting unit which will have a charging plug with it for the 240v mains, something like this where you could plug your existing power lead into it using a cigarette lighter socket: https://www.amazon.co.uk/PROGEN-BATTERY-PORTABLE-STARTER-COMPRESSOR/dp/B01MT6OTXK/ref=sr_1_119?ie=UTF8&qid=1494404272&sr=8-119&keywords=12v+battery+pack+jump

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You need a supply that will deliver a current of up to 2 amps at  12 volts for several hours.  This 12v 2A specification can be met in several ways - either from a mains power pack or an external battery.

Most users soon give up on the internal AA batteries. You don't need a battery as physically big as a car battery - a 7AH 12v sealed lead acid battery is adequate for powering the mount alone. There are issues with external plugs and leads - see here:-

The connector has to be the right design to snugly fit the socket on the mount. And make sure it's connected the right way round.

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11 hours ago, Andywilliams said:

....so the 'tip positive' on the power requirements is nothing to bother with?

That's very important - it either won't work or it'll damage something if you get it the wrong way round.

The pic posted above shows a good clear example of what goes where when you add the tip to a DIY lead.

You may well be able to buy a ready-made one with the correct tip type fairly cheaply. You could then choose what connector goes at the other end (cigar lighter plug / metal rings or U-shapes for connecting to screw connections / crocodile clips or other connector for 'car' batteries etc.)

I use a car battery because I had it spare. My lead for it is just a pair of crocodile clips on one end of two-core lawnmower flex with a cigar socket on the other end - because the cable that came with my mount has a cigar plug one end (and its tip the other of course). I just had to make sure I chose flex and connections that could take the power (in amps) that I was going to use.

If buying something new, I would probably look for a smaller lead acid battery or maybe one of the new Li-Ion batteries which are a lot lighter to lug about - but are more expensive.

There is lots of info and advice about all the options here on the forums, and there are solutions for pretty much every budget which is great.

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The trouble with croc clips at the battery end is that it is relatively easy to get them the wrong way around and despite taking every effort to ensure polarity is correct at the mount end of the lead, you'll still end up blowing up the board and need to fork out £100 for a new one... if you are going for a homemade DIY job, make sure the battery end is semi-permenanty connected to the battery terminals, or get some connectors which prevent you from getting polarity wrong that end of the lead. Most garages have a stack of "old" batteries they've taken off vehicals and are waiting for the scrap man to collect. I've sourced many this way and just give the garage £5 or so for each of them. Ideally take a voltmeter and check the resting voltagel if it's over 12.4v or so, it is likely an OK battery. You can get very inexpensive voltmeters online: https://www.amazon.co.uk/Volmeter-Voltmeter-digital-voltage-display/dp/B00PGOU8UM/ref=sr_1_14?ie=UTF8&qid=1494414002&sr=8-14&keywords=voltmeter

I get the impression thought, you might just favour a slightly more expensive, but easier option - in whcih case I'd just get one of these: https://www.amazon.co.uk/Silverline-234578-Silverstorm-Starter-Compressor/dp/B001C85UG8/ref=sr_1_8?ie=UTF8&qid=1494414123&sr=8-8&keywords=car+jump+starter or something similar.

James

 

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3 minutes ago, jambouk said:

The trouble with croc clips at the battery end is that it is relatively easy to get them the wrong way around and despite taking every effort to ensure polarity is correct at the mount end of the lead, you'll still end up blowing up the board and need to fork out £100 for a new one...

That's a good point. The clips have red and black sleeves so it's pretty obvious and I am very careful. But I may well revisit my croc clips - as I very rarely unclip them they may as well have one side semi-permanently attached. Hmmm I might even have the screw terminal somewhere...

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Thanks for all of the valuable info guys. I'm definitely not a handy man so I will probably be lazy and get the charger/compressor type pack and then there's no room for error!! 

This really is a goldmine site for us newbies.....so thanks, and clear skies !! 

Andy 

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Worth looking out for a second hand one on ebay, gumtree and the like. Even if the battery inside has degraded a bit I suspect you'll still be OK as the mount draws so little current. Again if buying second hand, worth just testing the resting voltage if you can, aim for one which is over 12.4v or so; anythign less suggests the battery may be giggered. If you get one, new or second hand, always recharge it after use if possible, don't leave it flat for long periods of time.

James

 

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Its worth knowing that if you go with a sealed lead acid battery you should aim for a leisure battery rather than a car battery. A leisure battery is designed to release power over a more steady period and can be discharged deeper with less risk of damage. Car batteries and jump start batteries are designed to give a high initial boost ( to get the car started!) and then discharge rather rapidly but of course are recharged by driving the car. So after a few long nights discharging car type batteries there is a tangible risk of damaging them.

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100% in agreement with John (Proto Star). I now use a leisure battery and it is very satisfactory. It's also important to use the correct charger. After a lot of research I bought a charger and battery from ebay.

Battery: http://www.ebay.co.uk/itm/200878944465

Charger: http://www.ebay.co.uk/itm/351952656036

The charger can be left permanently attached when not using the battery, but even if it isn't it's important to fully recharge the battery after use.

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I have to disagree.

The mount in question uses very little "power". A 7-17 amp hour standard lead acid battery will be more than sufficient for the needs of running this mount. There won't be any deep discharge if the battery is recharged after each use or after a couple of uses, or even after a weekend away camping. If dew bands, a laptop, heavy kit etc were involved this might be a different kettle of fish, but that isn't the case so I see no reason to for the person to track down a leisure battery and have to undertake DIY to make suitable connections for their mount and run the risks of getting polarity wrong etc.

This isn't a moan as the two previous posters, but I find there is a tedious infatuation with leisure batteries on SGL. They have their place, but for many users operating light weight kit in their backyard for one or two hours there simply is no need for them. Even when running more kit (and laptops), people (including myself) have been using conventional lead acid batteries for several years without a problem. If one understands a bit about how to care for standard lead acid batteries they can serve you very well and are considerably cheaper. The ability to obtain car jump starters like the ones shown above which are essentially sealed units and have a female cigarette style power port mean these are ideal for those who have no interest in DIY and just want a bit of power in the field for light weight mounts.

James

 

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G'day Andy, greetings from the world's most liveable city, Melbourne!

I have exactly the same scope and mount as you and my electronics genius brother in law got me this car jump starter and modified a lead for me. When I initially connected it to the mount the controller booted and went thru the alignment procedure but wouldn't slew the scope. Long story short, it ouput 16v and but thankfully the mount has an overload protection for the motors. He made the little white box in the pic with a nice long lead to connect  the green box and the scope so that it output 12v and voila, no more batteries - it's saving me a fortune

20170511_183919.jpg

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Most of the SW mounts can tolerate 11-16v (probably a wider range in relatity). If the mount won't slew, it is usually because the power source can't generate enough Watts. Someone I knew was trying to use a main transformer to run an EQ mount, but the maximum load was something like 800mA which just was insufficient. A car jump starter battery like the ones I showed above won't have this problem.

Macrob1 - having a mate who is an electronic genius is handy isn't it  :) I've got a mate who is also into astronomy and is a wizard with a soldering iron.

James

 

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I don't mean any disrespect, but I think some posters are making too much of a meal out of this. The OP has a basic GoTo mount which can run on 8X AA cells, so it does not need a lot of power or battery capacity just to run the mount alone for a few hours. As a step up from the internal AA cells, a 7 amp-hour 12v sealed lead-acid battery, or a good quality 12v 2amp regulated mains-powered supply unit (sometimes sold for this exact purpose), or a purpose-made power lead to connect to a vehicle cigarette lighter outlet will suffice.

When using any external power, it is essential to ensure that the plug is the correct fit (there are several variants that look almost identical) and is not making a poor connection. I use a cable anchor to stop the plug twisting in the socket. And that the + and (-) must be the right way round. Further details are in the 'GoTo FAQ'

 

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I would guess a lot would depend as James says on how/ where Andrew is going to use his scope/mount, if like me its mainly in the back garden then I wont be using the laptop etc on the battery as that is in the the wife's cocktail bar/ my astronomy shed plugged into the mains, the 12v/12Ah sealed lead acid battery I have has more than enough power to keep the mount going for days/ weeks/ months (weather dependent) as I have found out. 

If when we go to better dark sites then perhaps I would need a rethink but then I have a 12v/110Ah leisure battery in the caravan to use if need be but I probably wont take the laptop and just use the hand controller as there is enough data on that to guide me around to observe our universe! As you can guess I am not a serious astro bod unllike many of you on here with serious top equipment!

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My suggestion was based on my own experience of a car battery jump starters that eventually failed even though the usage was 3-4 hours on a regular basis and they were looked after and never flattened. Four others in our astronomy group have also fallen victim to car batteries that have not lasted any significant time. I don't think its over stating it all to use a leisure battery as it is about having the right tools for the job. Two hours now and again in OK conditions then maybe your car battery will be fine, start doing 3-4 hours or more with generous slewing in cold conditions and the game changes, especially after repeated discharges.

Ultimately buying cheap is one thing but having to buy twice is another. If the OP wants decent and reliable battery power and also a battery that will last him as the hobby grows, and something that gives confidence it will work in the field then I advocate getting a leisure battery.

Now I do not own a caravan and never will but those nice caravan people have put together a very good datasheet on batteries and it is well worth a read.

Hopefully it attached!

 

 

 

 

Datasheet-33.pdf

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Andy,

I use a 12V 1.5A or 12V 2A plug-top supply with my Skymaster Skymax 127. I come from an electronics background, so I wanted to find out the true power consumption. The scope takes 160mA when tracking and 350mA when slewing.

The compressor/charger packs should be fine if you want portability. They come with their own power brick to charge the internal battery, but DO NOT plug it into your scope. I have one of these, and have the power brick plugged into a timer switch to top-up for about 30 minutes every 24 hours.

Geoff

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Andywilliams, you've got a range of opinions and advice. There are very few black and whites in atronomy asin other areas of life. You pick, choose, modify the bits which you think will work for you and work on your budget. At the end of the day, it's just a hobby to enjoy. None of us fall out over these discussions, there are bigger things in life to worry about :)

Do keep us posted and let us know how you are getting on, and ideally share what you manage to observe, sketch or image.

James

 

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I run my skywatcher Virtuoso mount with a Celestron powertank the liFePo4 one.

It is super light and very small and a 7Ah it's plenty for me *you will not be able to run a dew heater as well from it. Lead acid battery was going to be too heavy and pain to remember to always keep it charged regardless of use.

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