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Adam1234

Power supply for go-to

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Hi, can anyone suggest a basic power supply to operate the Go-to on the 10 inch skywatcher dobsonian?

 

Thanks

Edited by Adam1234

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I’m not certain, but have been told that one of those jump start battery pack for a car does the job, and much cheaper than a power tank.

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I bought a LiPo car jump start unit, came with a car ciggy socket outlet too, was Yaber 20000mAh unit. Only BUT was I measured the output before hooking up and it was 16v, my SynScan upgrade manual says 15v max. So I added a 12v buck converter in-line from the ciggy socket to a 2.1mm plug to go direct to the mount and that gives a steady 12v to feed the GoTo. Not really had the chance to use it out under the stars, but spend a while testing and familiarising myself with the operation of the controller/mount, so had it powered and sweeping to targets for a good 45 mins and it hardly drained the battery pack at all.

Nice and light and compact compared to a lead battery unit, some advertise they're perfect for telescopes but I'd check the fully charged output before hooking up...

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Could be that 15V was just the open circuit voltage?  Still wise to put some sort of voltage limiter into the circuit though, I reckon.

James

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could be, but wasn't going to take any chances, not knowing what if any regulation there is in the pack itself :) 

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On 27/08/2019 at 16:18, Adam1234 said:

Hi, can anyone suggest a basic power supply to operate the Go-to on the 10 inch skywatcher dobsonian?

 

Thanks

I use an automotive jump start unit that works very well. It has two 12 vdc outlets, two 110 vac outlets, two usb outlets, and jumper cables. It has lasted five years thus far without issue and only cost $85.00 USD new from a home improvement store.

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do you know what the power draw will be for your complete setup?

The 7Ah will likely work fine but no idea what runtime will be. It will be heavy compared with lithium packs but then it has lighting and USB which not all the lithium starter units do. Don't forget to keep it charged tho and also don't drain it much below 50% too often, regular sealed lead acid batteries don't do well sat unused for months esp if low on charge or fully drained. Relatively cheap to replace the internal battery tho

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That is the same unit that I use with my 12 inch Dob. It works well so long as you keep it charged up regularly, but only lasts about 3 hours before running out of power. The 17ah unit would last a lot longer so may be a better bet if you can afford it.

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14 hours ago, DaveL59 said:

do you know what the power draw will be for your complete setup?

The 7Ah will likely work fine but no idea what runtime will be. It will be heavy compared with lithium packs but then it has lighting and USB which not all the lithium starter units do. Don't forget to keep it charged tho and also don't drain it much below 50% too often, regular sealed lead acid batteries don't do well sat unused for months esp if low on charge or fully drained. Relatively cheap to replace the internal battery tho

It requires a 12V DC power supply if that's what you mean by power draw?

I just looked on the specs for the my scope and they do actually recommend the 17Ah Power Tank so probably worth getting that one. Any idea on the size and weight of the 7Ah and 17Ah Power Tanks? I don't really want anything too bulky or heavy, just something that is going to be able to run the scope for a few hours.

Do you have any links to any of the lithium ones?

 

 

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never bought an astro powerbank but I know the 7&17Ah batteries as I use those in various UPS and the 17Ah is pretty heavy, 7Ah is around 2.6Kg and the 17Ah around 6Kg, so the powerbank will weigh a bit more than these numbers..

For the LiPo ones, amazon have several under the car starter search such as: https://www.amazon.co.uk/TACKLIFE-Portable-Car-Jump-Starter/dp/B075HBDN95/ref=sr_1_15?keywords=lithium+car+starter&qid=1567167387&s=gateway&sr=8-15

Best to test the output voltage tho and if needs be add a buck converter between this and the mount, such as:
https://www.amazon.co.uk/SUPERNIGHT-Buck-Converter-Voltage-Reducer/dp/B07CZBKZ9Z/ref=sr_1_16?keywords=12v+buck+converter&qid=1567167603&s=gateway&sr=8-16

Tho you can get lower cost ones depending on your current draw, best to check what current the battery pack can deliver as some smaller ones may not do well pushing a steady 2A out as they're really geared to low duration surge or low Amp steady load, check reviews before buying and if needs be ask the seller.

You'd need to fit appropriate connectors on the in/output of the buck converter to allow it to connect to the scope and use suitable cable to handle the current.

Note I'm not specifically recommending either of the above as I bought different ones but I don't find them on a quick search at the mo. I posted my setup in this thread which should give some clues to how :)
https://stargazerslounge.com/topic/338273-battery-for-powering-the-slt127/

Edited by DaveL59
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Thinking of going for this one? It's a bit pricier than one of the car jump starters, but a lot smaller and lighter which suits me, and at my current stage in my astronomy career I only need something that's going to power the scope for a couple hours and give me some enjoyment. 

https://www.firstlightoptics.com/batteries-powerpacks/celestron-lithium-lifepo4-powertank.html

Edited by Adam1234

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sounds fine, in fact a 10Ah LiFePo battery is as good as a 17Ah lead in performance terms so it may well last better. The batteries are quite expensive to obtain tho 3x or more than lead cells but then they may well last better so give a longer service life :)

 

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56 minutes ago, Adam1234 said:

Thinking of going for this one? It's a bit pricier than one of the car jump starters, but a lot smaller and lighter which suits me, and at my current stage in my astronomy career I only need something that's going to power the scope for a couple hours and give me some enjoyment. 

https://www.firstlightoptics.com/batteries-powerpacks/celestron-lithium-lifepo4-powertank.html

A nice battery 🙂   Just note it doesn't have a standard cigar socket outlet, so you'll need an adapter https://www.firstlightoptics.com/astronomy-cables-leads-accessories/lynx-astro-silicone-21mm-dc-jack-to-female-cigarette-socket.html or different a cable https://www.firstlightoptics.com/astronomy-cables-leads-accessories/lynx-astro-silicone-power-cable-21mm-dc-jack-to-21mm-dc-jack.html to use it  (if you get from FLO just email them to check the connections 😉 )

Helen

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1 hour ago, Helen said:

A nice battery 🙂   Just note it doesn't have a standard cigar socket outlet, so you'll need an adapter https://www.firstlightoptics.com/astronomy-cables-leads-accessories/lynx-astro-silicone-21mm-dc-jack-to-female-cigarette-socket.html or different a cable https://www.firstlightoptics.com/astronomy-cables-leads-accessories/lynx-astro-silicone-power-cable-21mm-dc-jack-to-21mm-dc-jack.html to use it  (if you get from FLO just email them to check the connections 😉 )

Helen

Thanks! This might be a silly question (new to all this), but why does it need a cigar socket outlet? I take it you don't get a direct cable?

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No silly questions 😉  it's all about learning 😁

I'm assuming you currently power your mount from a cable that looks like this https://www.firstlightoptics.com/astronomy-cables-leads-accessories/lynx-astro-mount-power-cable-for-sky-watcher-mounts.html - so has a fitting to go into a cigar socket.  There will be nowhere to plug that in to the celestron powrertank.  The celestron does come with a cable, but for a celestron mount, and the size is slightly different and so it may not work.

Hope that helps 😊

Helen

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Thank you,  I've got it now. Just checked in the pack of cables and yes I have that cable. 

I'll get the Celestron powertank and the cigarette socket adapter then 👍

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Cigarette lighter adapters are fine, but they often work loose over time, which is annoying as it means your need to realign when you reconnect.

An oft recommended alternative is the DIN connector which has a much more positive 'click' into place. Finding them can be a pain though, so try boating electrics suppliers. 

 

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This table shows the current consumption I measured on my various mounts.

1791626613_ConsumptionTable.jpg.da2d5954878f9d66fb0cafa9b05e9567.jpg

So, for the 10" Dob. spending most of the time tracking, an average consumption of 700mA gives 0.7Ah per hour, or 5 hours for a 50% discharge on a 7Ah battery.

Geoff

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