12v Cable Run // Pegasus Pocket power box

[8324689]

Hello, 

I am hoping this will work;

1st in the shed is mains power to my 12v 10A power supply with cigarette socket

https://www.amazon.co.uk/gp/product/B06Y2BGRMZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Which goes to the male cigarette plug cable that came with the Pegasus Pocket Power box to 5.1mm x 2.1mm jack

I will then extend the 5.1mm x 2.1mm cable by approx 7 meters using this cable and appropriate connectors in to the Pegasus situated on the scope, on the pier.

https://www.amazon.co.uk/gp/product/B07F6D7DBB/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

 

Should be good!?

Cable run not too long?

 

Thanks 

 

Edited October 11, 2020 by 8324689

[8324689]

Sorry maybe this belongs in the begineer forum....

Last dumbo entry I promise...

So using this calc I believe its not going to work given my cable is 20 AWG...

https://www.rapidtables.com/calc/wire/awg-to-mm.html

I suppose Ill have to put in a 10m IEC mains cable to the pier plugging in the cigarette power supply.

I am reluctant to do this as I do not want the large power supply on the pier I would much prefer it in the shed under proper cover

 

 

 

Edited October 11, 2020 by 8324689

[Seelive]

The voltage drop with a 7m length of 20AWG twin core wire will be around 5V at 10A, so not much left out of the 12V you start with. You could use a 2.5mm flex cable (e.g. https://uk.farnell.com/pro-power/3182y-2-50mmblk100m/flex-cable-2core-black-2-5mm2/dp/2425457?st=Multicore cable) which at 7m would drop about 1V at 10A. Flexible cables above 2.5mm are about as rare as rocking horse **** but if flexibility is not a specific requirement you could use 4mm twin and earth which is readily available. 

[8324689]

Thanks for this it definitely makes things a lot clearer for me. 
 

I do  think unfortunately I will go to mains route. 
it means the power supply will be under the inverted dustbin when not in use and a little bit cumbersome with cables 
but probably the most straightforward route

 

 

Edited October 11, 2020 by 8324689

[8324689]

Thanks 

Edited October 11, 2020 by 8324689

[Seelive]

24 minutes ago, 8324689 said:

I wish there was a smaller profile powersupply though

How big is your existing PSU? This one is 180mm x 65mm x 40mm https://uk.farnell.com/powerpax/sw3477d/ac-adaptor-12v-10a-reg-3-pin-vi/dp/3375895 which seems to be typical for a 120W PSU.

[8324689]

Yes mine is similar - Its just the contour of the pier I cant have it that neat there will be .5m mains cable and cig socket hanging about. I just wanted to get it as neat as poss -I should stop moaning !

[mallorcasaint]

I have two 13.8 v bench supplies in my obsy warm building with 3 seperate runs of 12 volts running underground  to the pier. One 12 v supply converst to 5 v at the pier end so all my equipment is adequately supplied and no mains needed at the pier.

[8324689]

need to dbl check

Edited October 13, 2020 by 8324689

[Birman1]

As suggested by Mallorcasaint keep mains away from the pier to avoid safety problems and the necessity for a mains rated exterior enclosure and proper  earthing of all metal. Using 4mm cable will give a small dc voltage drop over 7m. You can use more flexible cable at the pier end if you mount a junction box on the pier. Look at https://www.12voltplanet.co.uk for cables and connectors. Good luck

[8324689]

Shoot was trying to get. all purchases from same site i cannot

 

Looks like Ill by the cable suggested above from Farnell and supply from CPC/Farnell

 

Thanks all

 

 

Edited October 13, 2020 by 8324689

[8324689]

So I got a 13.8 power supply and 10 m of the cable. 
using a calculator I had expected approx .7 V drop with at 7 m

 

I plugged it into the 10 meter line cable and read the volts and it was 13.8 🤷‍♂️
 

i’m not complaining - it’s nice to have good juice ! But still maybe I was fine with the cheaper option!

Edited October 16, 2020 by 8324689

[pete_l]

1 hour ago, 8324689 said:

using a calculator I had expected approx .7 V drop with at 7 m

When drawing how many Amps?

If you just measure the voltage at the remote end without a load in place, the reading will not be any different than at the supply.

You need to know what the maximum instantaneous current will be when all your kit is connected. Then ascertain what the supply voltage is at that instant. IME very many mysterious problems that people experience with their astronomy kit is due to dodgy power from supplies that drop to below the minimum required. Even if that drop is only for a few milliseconds, for example when the motors on the mount both start up and both take a switch-on surge current.

That's the real test!

 

[8324689]

6 hours ago, pete_l said:

When drawing how many Amps?

If you just measure the voltage at the remote end without a load in place, the reading will not be any different than at the supply.

You need to know what the maximum instantaneous current will be when all your kit is connected. Then ascertain what the supply voltage is at that instant. IME very many mysterious problems that people experience with their astronomy kit is due to dodgy power from supplies that drop to below the minimum required. Even if that drop is only for a few milliseconds, for example when the motors on the mount both start up and both take a switch-on surge current.

That's the real test!

 

Aha ! Thank you for this! 
of course. 
learning all the time! 

[symmetal]

You can get 2 core stranded cable from many sites on ebay like this up to 4.5mm. At £22 for 10m it's not too pricy. 😀

Alan

[8324689]

Thanks everyone I’m done and dusted cable installed etc! 
 

thanks for your help