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Portable Power Supply


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I have just bought an etx-ls (being delivered tomorrow) and am unsure as to what Power supply to use with it as there are quite a few about (I've read that using standard batteries will prove both expensive and frustrating due to them being quickly exhausted)

I have a budget of up to £100 to spend on a portable power supply. Can anyone offer some advice on the best one to get.

Thanks!

SC

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if it takes the 12v dc power supply, get yourself down to maplins and have a look at the 17ah powerpacks there for £25, it`s an all in one jump starter job and it works very well with my celestron cg5 gt mount, also think that aldi had some in last week with two cigar connections on it for about £30, can`t go wrong in my view for the money but remember to keep them fully topped up as it helps keep the life of the battery

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if it takes the 12v dc power supply, get yourself down to maplins and have a look at the 17ah powerpacks there for £25, it`s an all in one jump starter job and it works very well with my celestron cg5 gt mount, also think that aldi had some in last week with two cigar connections on it for about £30, can`t go wrong in my view for the money but remember to keep them fully topped up as it helps keep the life of the battery

I have one of the starter packs with jump leads and cigar 12v sockets, it came with my Lx90 and it's spot on for the job, also been great with my flat battery on these cold mornings.

Stu

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A secret with these type of things is try and get a volt meter wired in if you can.

As soon as a 12v battery actually drops to 12v, the fall from there is precipitous, and that's when the damage gets done to the battery. So a 12v reading or just under, is the time to turn things off.

These Oximiser Battery Charger are brilliant value (0.6 amp trickle charger) for conditioning batteries and keeping them in good health. I have heard that they even have a good chance of reviving batteries that have been deep discharged.

There's an SGL member that made their own 12v power supply, using a 105amp battery, and did an outstanding job of showing what was involved. Obviously you don't have to go with a battery that heavy of that amperage (e.g. an alternative is the 32ah lawnmower battery here Numax Lawn Mower Batteries - Lawnmower Batteries ) .

Then using something like this LUPO Triple Cigarette Lighter Charger Adapter + 1 USB: Amazon.co.uk: Electronics & Photo built into a carry case, you can have 3 sockets and a USB power supply.

I'll see if I can find the link to the SGL member's fine effort.

Still searching, and found a link to this which looks a nice job Portable Power Supply

OOoo! another nice link power

Large Marine Plastic Battery Box LARGE MARINE PLASTIC BATTERY BOX caravan motorhome boat on eBay (end time 14-Feb-10 13:11:55 GMT)

Smaller NEW BATTERY BOX YACHT BOAT MARINE CARAVAN CAMPER VAN on eBay (end time 10-Mar-10 16:45:15 GMT)

Sockets that should handle 10amp (they have cigar lighter elements with them) 12v Power Cigar Cigarette lighter/charger socket plug on eBay (end time 10-Mar-10 23:27:38 GMT)

Nice cheap voltmeter 12V Battery Voltage Meter, Voltmeter 11.0 to 14.7V on eBay (end time 09-Mar-10 15:33:18 GMT)

It would be very fast and not much more expensive than a cheap powertank, to knock something together that's really heavy duty and easy to maintain in comparison.

Stick one of these 12v 24v Car Truck USB Charger Socket Adapter for Ipod.. on eBay (end time 23-Feb-10 12:36:40 GMT) in one socket, then plug in a USB hub, and you can have all sorts of USB stuff powered (e.g. USB LED Laptop Light/Lamp METAL Flexible Low Power UK on eBay (end time 06-Mar-10 11:14:08 GMT) ).

Nice 40 amp gel battery here (and as an aside, I am shocked to see the profiteering on these battery prices, at sites that supposedly cater to the disabled this exact same battery listed at around £110 :) ) - MOBILITY & GOLF BATTERY 12V 40AH GEL on eBay (end time 11-Feb-10 21:19:35 GMT)

Edited by Ogri
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I'll see if I can find the link to the SGL member's fine effort.
That would be me ;) Thanks for the comments :) - link is: http://stargazerslounge.com/diy-astronomer/95646-105ah-powertank.html. I wanted to be able to run mount, PC, dew heater and camera all from the same power supply hence the Ah rating (and weight - the whole thing weighs in at 25kg....)

The key is to get something to look after it. I use an CTEK multistage charger - I have the 7A one, but the 3.6A one would be better for smaller batteries (and at half the price saves in teh pocket department too!)

Edited by arad85
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That would be me :D Thanks for the comments ;) - link is: http://stargazerslounge.com/diy-astronomer/95646-105ah-powertank.html. I wanted to be able to run mount, PC, dew heater and camera all from the same power supply hence the Ah rating (and weight - the whole thing weighs in at 25kg....)

The key is to get something to look after it. I use an CTEK multistage charger - I have the 7A one, but the 3.6A one would be better for smaller batteries (and at half the price saves in teh pocket department too!)

Well credit where it is due, it was a fine effort. :D

I've been scurrying round the web for some basic sources of stuff (and have updated the above), and was over the moon finding things like the marine battery boxes - a fair selection on ebay.

I'm still bouncing over the profiteering of the disabled though. :) If people are retailing the exact same thing at less than £50, they are obviously happily making a profit at that (I am not anti profit either, I recognise how essential it is), so boosting it up to £110 makes my blood boil.

In America they have anti 'price gouging laws' as they call it, and people can get very heavily fined and go to jail for it.

We need the same here.

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Sorry to hijack but hope it helps! I have one of these which seemed to work well:

Buy Gifts, Crafts & Collectables | homeshopping.24studio.co.uk

I assume this is the same sort of thing as the Maplins one? I haven't checked if it has run down and become useless! :) Is this the sort of thing the Oximiser can be used to keep charged up??

Also, when on, can the clips be dangerous to touch? I'm not an electrical sort of person so am completely stoopid about this!

Alexxx

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Yup, same sort of thing as the maplins type. I destroyed a similar type (it is easy to do either by overcharging or draining too much) hence why the excursion into leisure batteries.

As to dangerous to touch: they generally have a switch that makes the jump leads live, but that would still be OK to touch with your hands 12V DC isn't a high enough voltage to kill you. If you touched them together through something conductive (cable, screwdriver etc...) be prepared for a very big bang as all the hundreds of available amps flow in one go! If in ANY doubt, don't mess/touch. There is an awful lot of power in those batteries........

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Don't worry 12v clips are ok.

"Is this the sort of thing the Oximiser can be used to keep charged up??"

Yes, you get a lead with permanent ring fixings to connect to a battery, with a 2 pin socket on it, plus a lead with 2 crocodile clips and a 2 pin socket on it. The charger then has a lead with the 2 pin plug at the end.

Just hook up the red crocodile clip to the red crocodile clip on the battery pack, and the black to the black, and you are good to go. :)

eta: if the casing is easy to open on these things, then you could permanently fit the connector lead with the ring connections. Maybe drill a hole big enough to get the little rings through in the case, and hot glue the socket to the outside for ease of use? You can get spare leads too - http://www.mandp.co.uk/productinfo/500071/Workshop/Battery-Chargers/Optimate and http://www.mandp.co.uk/productinfo/567203/Workshop/Battery-Chargers/Optimate etc.

Edited by Ogri
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I like the look of these batteries:

MK 12 VOLT 35 AH HIGH QUALITY GEL BATTERY,13cm wide,19cm long,16cm high

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110488716036&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en

That height (160mm) should work well with the 234mm external height (210 internal) of the small battery box I posted the link to above, leaving good clearance for the fitment of sockets, etc.

Postage is a bit heavy (just under £15) but still a good deal on a deep cycle battery.

Heeey, now here's a thought - how about someone good at this sort of thing, doing a hands on powerpack building course at SGL5 for those that are going?

List the components to bring, and everyone interested could put their own together on the course? It would be very easy for everyone to maintain their own from then on?

If there were enough numbers, I bet there'd be really brilliant discounts for a group buy too!

eta: Well I've ordered one of these 35 amp hour batteries (bouncing again, a disabled specialist gear outfit sells them for £92!!! :) ), plus one of the smaller marine battery boxes, and a volt meter. I won't order any of the other stuff until I have it all delivered and can double check all the height, width, etc clearances as they really are, Can take some photies of what it looks like in the box, etc., then, and upload them to photobucket.

Edited by Ogri
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Could someone STICKY this thread? Maybe also a few electrical whizz kids describe the correct wiring to make these things up. I know that they are comparativly simple to do - but a bit of guidance would help!! (eg wiring sizes & fusing etc.)

Thank You

Edited by Bizibilder
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Just found this which looks rather funky

Skywatcher 7Ah Rechargeable Power Tank

Would it suffice?

Well the cheaper Maplins type at 17 ah, would give you almost 2.5 times the amp hours.

It does seem as though a fair few people quickly run into limitations with the 17ah too. Discharge them too much, and then they die fast as well.

That's why I was thinking of the 30 - 40ah range as about doubling the 17ah capabilities, plus using a deep cycle gel type battery for very long life (especially if you still don't deep cycle them), then put it together (hopefully to Alex's standards) with good heavy duty wire so there's no overheating risk, have easy access fuses, and such, along with a voltmeter to be instantly able to visually check the real state of the battery, with it all hopefully in a package weight that isn't going to be doing people's backs in (a 105ah battery, to be fair, is a fair old lump for some people to risk shifting - including me these days, sad to say).

ETA: would a mains power supply do if using from home, or even tide you over for a bit?

ETA2: Bizibilder I'm going to try and do it all as simple as I can and take photo's, and only use simple stuff like crimped spade connectors (with a bit of heat shrink for the joints perhaps) so all anyone would need is a cheap crimp tool kit (which may have all the connectors necessary already with it), a pair of pliers/wirecutters, and a Stanley/Modelling Knife to cut the openings for voltmeter and sockets. No soldering! I promise! :)

Any guidance from 'them that knows' along the way will be more than welcome too! ;)

Edited by Ogri
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Well the cheaper Maplins type at 17 ah, would give you almost 2.5 times the amp hours.

I'm a little confused as to the amp hours thing. Am I right in thinking 17Ah gives you 17 hours (of 1 amp per hour @ 12v) before the battery is completely exhausted?

Also, what sort of current does a 6 inch scope draw an hour (or is that a 'how long is a piece of string' question)

Cheers :)

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I'm a little confused as to the amp hours thing. Am I right in thinking 17Ah gives you 17 hours (of 1 amp per hour @ 12v) before the battery is completely exhausted?

Also, what sort of current does a 6 inch scope draw an hour (or is that a 'how long is a piece of string' question)

Cheers :)

Yes that's right, 1 amp draw for 1 hour is 1 amp hour. Plus watts = volts x amps is always handy to remember. ;)

No idea on the power drain sorry, I don't have anything electrically driven (yet), but it does seem that once you have one thing that's using the amps, other stuff that's using amps quickly follows along. So say a 5 - 6 hour session at total 5 amp drain means 25 - 30 amps needed in the bank (so a 34 ah battery should never get too stressed out).

Good news with laptops and such, my sister bought one of the new Acer 1810's (I know Dell do something similar now too), with the new ultra low voltage dual core Intel CPU (good chipset too, as it has the Intel 4500 graphics built in - compatibility, compatibility, compatibility). She's getting 7+ hours of use online via wifi, and from fully charged at least enough time to watch 2 videos (also feeding power to the external USB DVD drive). So I would imagine this sort of technology is going to become more easily available and price competitive soon.

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mounts are in the 2 amp per hour draw rate, well the celestron cg5 gt is and i`m fairly certain the skywatchers are, so a 17ah power plant should give you 8 hours, you might need more if you are running dew heaters and so on as extras. the gel battery as shown on e bay above is a very good price even with delivery, but then you`ll need a charger for it.

Edited by red dwalf
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so a 17ah power plant should give you 8 hour
You will never get this out of these tanks. With a 2 amp draw you will be lucky to get 4 hours before the voltage drops too low to drive the mount. I certainly never got much more than this with mine (which has thankfully died, even despite the attentions of one of those 3-stage chargers).

NigelM

Edited by dph1nm
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