Power Options for EQ5 (Non-Goto)

[JohnSadlerAstro]

Hi,

I'm currently using a very cheap mains to 6v adapter for my EQ5. However, I've noticed that the motors are a behaving a bit erratically while guiding, so I want to change to a more steady power supply to help reduce this.

Looking on FLO, most stuff seems to give 12v, double what I need. I'm new to the power supply area of astronomy, and it's all a bit confusing! 

What kind of setup should I use? Is there anything I can get for around £50 from FLO that will give 6v DC from mains?

John 

[nightfisher]

Have you considered using a 3000mah 3s lipo battery with a 6v bec, this would last weeks before needing a recharge, and would give a clean 6v dc output

 

[spaceman_spiff]

Are you using the EQ5 pro or just the basic motors? I have the EQ5 pro and it works well with a 12V 17Ah motorcycle battery.

[JohnSadlerAstro]

1 hour ago, spaceman_spiff said:

Are you using the EQ5 pro or just the basic motors? I have the EQ5 pro and it works well with a 12V 17Ah motorcycle battery.

I'm using the basic motors, with the new upgrade handset. 

https://www.firstlightoptics.com/skywatcher-mounts/enhanced-dual-axis-dc-motor-drives-for-eq-5.html

 

[spaceman_spiff]

21 minutes ago, JohnSadlerAstro said:

I'm using the basic motors, with the new upgrade handset. 

https://www.firstlightoptics.com/skywatcher-mounts/enhanced-dual-axis-dc-motor-drives-for-eq-5.html

 

Good to know!

AC power supplies need to be well regulated - producing a nice smooth DC current in order to get stable movement from the motors. Cheap ones (i.e. the little plug in ones with the multiple jack attachments) just don't cut it.

If you want to be completely safe then go for the battery solution. I used to have the dual axis motors and I just bought some beefy rechargeable D cells and they were OK.

Dan

[JohnSadlerAstro]

This kind of thing?

https://www.amazon.co.uk/EBL-Universal-Discharger-Rechargeable-Batteries/dp/B011TRBX44/ref=sr_1_4?ie=UTF8&qid=1520858746&sr=8-4&keywords=Rechargeable+D+cell

[spaceman_spiff]

25 minutes ago, JohnSadlerAstro said:

This kind of thing?

https://www.amazon.co.uk/EBL-Universal-Discharger-Rechargeable-Batteries/dp/B011TRBX44/ref=sr_1_4?ie=UTF8&qid=1520858746&sr=8-4&keywords=Rechargeable+D+cell

Exactly! They look way better than my old Energizers and have 4x the capacity.

[JohnSadlerAstro]

There is slightly less voltage, they appear to be 1.2 v not 1.5, could that be an issue though?

[spaceman_spiff]

It should work...My old batteries were also 1.2V (I think...) and they worked. The only issue is capacity. I used the motors only for short periods when I was purely observing. If you wish to do imaging then you will need something a bit more heavy duty.

There is another option if your are worried...you could look for a 6v Lead acid gel battery.

Here's a link:

https://www.amazon.co.uk/PS6100-10AH-NonSpillable-Rechargeable-Battery/dp/B00LZV1C5U/ref=sr_1_11?ie=UTF8&qid=1520862365&sr=8-11&keywords=6v+Gel+battery

Of course you will need a balance charger and electrical clips to connect it.

[JohnSadlerAstro]

So in theory, the 1.2 D cells have 40 amp-hours between them. The mount draws around 1-1.5 amps at 6V. Therefore, at 4.8 V, it will probably draw about 2 amps. That should then give around 10-15 hours of steady power. 

Alternatively, if I were to get the standard 1.5V 2.5 amp-hour D cells, that would then be 10amp-hours in total. If the mount draws 1-1.5 amps, that will give around 6 hours reliably. Technically, that is actually enough, as I normally on start imaging after midnight when the council decides to cease the night sky illumination and switches off the nav beacons positioned on every corner.  

[Dr_Ju_ju]

remember to factor into your calculations, that cold temperatures, reduses the power output of batteries....

[JohnSadlerAstro]

An edit to my original calculations, the "instructions" if you can call them that--(We all know Skywatcher ) give a minimum requirement of 0.4 amps. Allowing for guiding and cold, it will probably be around 0.75-1. With 10 amp hours in total in the battery pack, that will leave me with around 6-7 hours, with a broad margin for lost power due to the cold batteries.

[Alien 13]

Mobile phone power banks (5.2 V at 2A) work fine with these mounts, they are cheap, lightweight and are available at various AH ratings.

Alan