12A power supply for Skywatcher HEQ5

[Jezphil]

When I use my 12V Skywatcher power adapter for my HEQ5 mount, it works only intermittently. Sometimes simply refuses to budge or react in any way on instruction to do so.  If I run the power at 12.8V however, from a Primalucelabs Eagle4 mounted on the scope, the mount works fine. I've read somewhere that 12V is actually slightly low for an HEQ5 mount. Anyone else encountered this issue? Why don't SkyWatcher slightly bump up the voltage, say to 12.5 or 12.8 to account for this?

[Padraic M]

Yes the HEQ5 doesn't like a voltage below ~11.5V. When you draw current from the PSU, the voltage will drop and the mount can behave erratically. I use a 13.8V Nevada Radio PSU and it works perfectly.

[Alien 13]

I think the 12V is probably correct but you could easily loose 0.4 V or more in cable resistance, never understood why most commercial PSU units dont have an optional 4 wire option to remote sense the voltage at the actual mount connection.

Alan

[Jezphil]

3 hours ago, Padraic M said:

Yes the HEQ5 doesn't like a voltage below ~11.5V. When you draw current from the PSU, the voltage will drop and the mount can behave erratically. I use a 13.8V Nevada Radio PSU and it works perfectly.

Thanks for this. Would it be this you are using?...  https://www.firstlightoptics.com/batteries-powerpacks/nevada-ps-08-6a-8a-regulated-linear-power-supply.html

[fozzybear]

I use one of these left over from my Amateur radio days and serves me fine with various outputs 

[Jezphil]

14 minutes ago, fozzybear said:

I use one of these left over from my Amateur radio days and serves me fine with various outputs 

Thank you. So that's 10A. Is that what you are using? I was thinking 12A was too low. Or is your one higher amps?

[bosun21]

32 minutes ago, Jezphil said:

Thank you. So that's 10A. Is that what you are using? I was thinking 12A was too low. Or is your one higher amps?

12A ??. The rating for the HEQ5 is only 2A at 12v. If you increase the voltage to say 13v then the mount will draw slightly less than the 2A

[Skipper Billy]

I think you are confusing volts with amps.

The HEQ5 is designed to work off a 12v battery which is about 13.7 volts when fully charged and below 12v is 'flat'

The ampage is irrelevant as long as it is high enough to power the device so whether its 10 amp or 12 amp doesnt matter as it only requites ~2 amps,

Edited March 18, 2022 by Skipper Billy

[Skipper Billy]

Any good ??   https://www.astrobuysell.com/uk/propview.php?view=184600

 

[Padraic M]

2 hours ago, Jezphil said:

Thanks for this. Would it be this you are using?...  https://www.firstlightoptics.com/batteries-powerpacks/nevada-ps-08-6a-8a-regulated-linear-power-supply.html

It's actually this one... https://www.firstlightoptics.com/batteries-powerpacks/nevada-psw-30-25-30a-switch-mode-power-supply.html

I was using as 12V 10A generic brand power brick so when I needed to upscale I went for 30A. It's way more than enough to power the mount, camera cooler, dew bands, Mini PC etc.. and it never draws more than ~3A even when slewing.

[bosun21]

47 minutes ago, Skipper Billy said:

I think you are confusing volts with amps.

The HEQ5 is designed to work off a 12v battery which is about 13.7 volts when fully charged and below 12v is 'flat'

The ampage is irrelevant as long as it is high enough to power the device so whether its 10 amp or 12 amp doesnt matter as it only requites ~2 amps,

That’s exactly what I said the OP was talking about the amperage not me. I am an Electrical and Electronics engineer so I’m well versed in all things electrical.

[Jezphil]

Ah - apologies. Yes, I ended up getting volts and amps confused!  Anyway thank you for this link below, which is really helpful and I will go for this as a solution...

https://www.firstlightoptics.com/batteries-powerpacks/nevada-psw-30-25-30a-switch-mode-power-supply.html 

 

 

[malc-c]

That's nice, but you don't need 30A to drive an HEQ5.  A PSU capable of supplying 5A @12v (ie 60watts) still gives you stacks of head room.   13.8v PSU rated at 5A would be perfectly adequate 

Edited March 18, 2022 by malc-c

[Skipper Billy]

10 hours ago, bosun21 said:

That’s exactly what I said the OP was talking about the amperage not me. I am an Electrical and Electronics engineer so I’m well versed in all things electrical.

My comment was to the OP not you.

[StevieDvd]

17 hours ago, Jezphil said:

When I use my 12V Skywatcher power adapter for my HEQ5 mount, it works only intermittently. Sometimes simply refuses to budge or react in any way on instruction to do so.  If I run the power at 12.8V however, from a Primalucelabs Eagle4 mounted on the scope, the mount works fine. I've read somewhere that 12V is actually slightly low for an HEQ5 mount. Anyone else encountered this issue? Why don't SkyWatcher slightly bump up the voltage, say to 12.5 or 12.8 to account for this?

To answer the last part of the question about higher voltage, the answer is that they do.

See HEQ5-Pro specs it can take 11-15v so a 13.8v supply  (like a car battery etc) is within the range allowed.  Always good to see what the manufacturer states as required.

I read in later SW mount manuals where 11-15v is specified that the 11v needs a higher amp rating quote:

"Output Current: 4A for power supply with 11V output voltage, 2.5A for power supply with
16V output voltage."

So perhaps the psu you have does not have enough amperage to supply a steady 11V.

 

[Cosmic Geoff]

27 minutes ago, StevieDvd said:

I read in later SW mount manuals where 11-15v is specified that the 11v needs a higher amp rating quote:

"Output Current: 4A for power supply with 11V output voltage, 2.5A for power supply with
16V output voltage."

So perhaps the psu you have does not have enough amperage to supply a steady 11V.

That is curious behavior, but quite possible for a switch-mode device which boosts the voltage up to a constant level. (There is an indication elsewhere that these mounts develop a higher voltage internally to drive the motors.) At one point in my career I was designing (not too successfully) a switch-mode power supply that boosted a battery voltage up to a constant level.  I found that the lower the input voltage, the greater the input current (as above) and that a nasty feedback loop was liable to develop which dragged the input down...

[Jezphil]

1 hour ago, StevieDvd said:

To answer the last part of the question about higher voltage, the answer is that they do.

See HEQ5-Pro specs it can take 11-15v so a 13.8v supply  (like a car battery etc) is within the range allowed.  Always good to see what the manufacturer states as required.

I read in later SW mount manuals where 11-15v is specified that the 11v needs a higher amp rating quote:

"Output Current: 4A for power supply with 11V output voltage, 2.5A for power supply with
16V output voltage."

So perhaps the psu you have does not have enough amperage to supply a steady 11V.

 

Thank you. I was referring to the power adapter which only supplies 12V as I understand it. Why not make that, say, 13V when 12V can create intermittent issues like I experienced? Great that the mount itself can go to 15V but they could bump up the power from the adapter. It just seems that 12V adapters are on the edge of being too low for the HEQ5, or that they aren't that reliable and maybe can easily be delivering below 12V. It doesn't allow much margin for error if the voltage from the adapter is slightly low maybe? 

[StevieDvd]

Did that psu come with the mount - and are both new? It's 12v but what amperage.

There are many SW mounts that can use a 12v supply but the amps may differ slightly, for example the AZ-GTi needs far less amps (min  750mA) and a psu from 7-14v

 

[Jezphil]

2 hours ago, StevieDvd said:

Did that psu come with the mount - and are both new? It's 12v but what amperage.

There are many SW mounts that can use a 12v supply but the amps may differ slightly, for example the AZ-GTi needs far less amps (min  750mA) and a psu from 7-14v

 

Yes, it's the branded one actually supplied by SkyWatcher that came with the mount and is noted on the back as 12V and 5A. I am using it purely for the mount, nothing else. Why wouldn't they do it for slightly more than 12V to avoid issues with under powering? Posing this HEQ5 with slightly more eradicates the issue, I have found. And I think that's what others have found also, from what I have seen.

[Jezphil]

Just now, Jezphil said:

Yes, it's the branded one actually supplied by SkyWatcher that came with the mount and is noted on the back as 12V and 5A. I am using it purely for the mount, nothing else. Why wouldn't they do it for slightly more than 12V to avoid issues with under powering? Posing this HEQ5 with slightly more eradicates the issue, I have found. And I think that's what others have found also, from what I have seen.

Mount and adapter are around two years old btw. 

[StevieDvd]

43 minutes ago, Jezphil said:

Yes, it's the branded one actually supplied by SkyWatcher that came with the mount and is noted on the back as 12V and 5A. I am using it purely for the mount, nothing else. Why wouldn't they do it for slightly more than 12V to avoid issues with under powering? Posing this HEQ5 with slightly more eradicates the issue, I have found. And I think that's what others have found also, from what I have seen.

That should be fine if working properly. There have been instances where the connection was loose at the socket causing intermittent issues - but if you have a working solution now is that OK?

Otherwise you'd need to try another 12v/5A psu to see if that replicates the problem or not.

The bad connection for some folk was resolved by using better jack & sockets like the GX12-2 - which SW themselves went with on newer mounts.

 

[bosun21]

6 hours ago, Skipper Billy said:

My comment was to the OP not you.

My apologies @Skipper Billy

[Jezphil]

13.8V supply now ordered for this. Thank you everyone for your help and advice. Much appreciated - what a great community this when you need help 👍

[Skipper Billy]

1 hour ago, bosun21 said:

My apologies @Skipper Billy

Nae botha 😉