Astro rig PSU recommendations needed please

[dazzystar]

Hi All,

Apologies if this question isn't in the right place but I need recommendations of a portable astro 12v PSU. Can anyone recommend something they use?

Cheers
Daz

[lardy]

Hi Daz,

A 12 volt leisure battery pack ? 
 

They do sell dedicated battery packs that last the night for astronomy or knock up one based around the above.

 

Regards

Mark
 

 

[teoria_del_big_bang]

You first need to know what size of supply you need and how long you are wanting it to last.

• What equipment do you have to run from the 12V supply ?
• How long do you want a session to last ?

Steve

[dazzystar]

2 hours ago, teoria_del_big_bang said:

You first need to know what size of supply you need and how long you are wanting it to last.

• What equipment do you have to run from the 12V supply ?
• How long do you want a session to last ?

Steve

Thanks Steve.

I'll be running an EQ3 mount (soon to be upgraded by the addition of a OnStep mod), an ASI183MC camera, An ASI120MM or similar small guide camera, and a Beelink U59 mini PC (12v 3A). Hope that helps.

[david_taurus83]

When you say portable do you mean back garden session portable or trips out to dark site portable? If back garden then have you considered all possibilities of a mains supply ran outside? If this isn't feasible I'd recommend a leisure battery. If its kept charged between sessions you shouldn't ever need to worry about running out of power. If for travelling, might br worth looking at a Lifepo type battery as their much lighter. Think their used in golf carts etc. The Tracer LiFePo range are good but expensive.

[teoria_del_big_bang]

3 hours ago, dazzystar said:

Thanks Steve.

I'll be running an EQ3 mount (soon to be upgraded by the addition of a OnStep mod), an ASI183MC camera, An ASI120MM or similar small guide camera, and a Beelink U59 mini PC (12v 3A). Hope that helps.

So there in theory you have a maximum of about 2A for EQ3 (a bit of a guess), 3A for ASI183MC, less than 1A for ASI129MM and 3A for the PC, so a total max amperage of 9A, if my maths is right.
But, it will never need all that as the mount only takes anywhere near 2A when slewing, when tracking less than 0.5A, the ASI183MC will not ever get to 3A and will only take towards 2A when cooling is 100%, again otherwise probably around 1A, the PC could be quite hungry for power but again if it specifies a supply of 12V 3A then probably will be around 2A (could be less).
Only way to check for sure is to measure with an ammeter or power meter, but I would hazard a fair guess you are looking at needing something capable of delivering 6A as a maximum but the average will probably be around 3A.

So if you wanted a supply to last 8 hours then you are looking at a 12V supply at 24 Ampere hours (3 x 8). This is all a bit of a guess but you get the idea.
Also bear in mind what you may add, a couple of dew bands for example that may add another 1 to 1.5 A.

So then it depends whether this is for backyard or on the go as @david_taurus83 states.
The cheapest route is a leisure battery but you probably will have to do some work boxing it up and adding some sockets. If you are capable of a bit of wiring then this is a popular way to go, but these car type batteries are heavy if you are on the go so the  Lifepo type battery are much lighter, but more expensive.

Steve

 

Edited February 7, 2022 by teoria_del_big_bang

[dazzystar]

I can't see the scope being used for more than 3 - 4 hours per night in the garden. We may decide to go to a star party so would need to think about that in more detail.  I'd have a power splitting box (DIY) to deliver 12V power to each device from a 12V power source for neatness of cabling (just one cable from the ground to the scope instead of several). The Tracer batteries are very expensive and therefore a no-go for me. Both ZWO cameras are un-cooled and are powered by the USB ports on the mini PC but the ZWO doesn't give current draw specs but it has to be 500ma or less if I remember correctly as this is the max current per USB port.

The 12V 3A figure I gave you for the Beelink U59 mini pc is just what is written on the mains power supply it comes with and according to various tests uses an average of 11W with a 23W max.

 

 

[teoria_del_big_bang]

Ah if uncooled and on purpose I was over estimating to be safe so looks like you are drawing 1 to 2A then so if you worked it around maybe getting 6 hours to have a safety margin you are looking at something over 12 A/hr (even working on the high end)  but if you are getting a leisure battery then not good to run them right down at all it can damage them so probably looking at something around 17A/hr or more.
Also important to charge the battery back up after use and even when not using and stored you should periodically put on charge to top them up as they will lose charge.

Steve