Low voltage issue

[Saturn488]

Currently running an HEQ5 mount with a Pegasus Power Box and a 12V DC 10amp power supply.

For some reason I am only drawing 11.1V - 11.2V and getting a red flashing light on my mount. It flashes really quick when slewing.

It sounds like I may need a more reliable power supply. Currently hooked into an extension cable that has 4 outlets on it, that could be the reason why?

Any tips or recommendations for a really good power supply that can support a constant 11.8V or more?

[AdamJL]

What's the 12V DC 10amp one?
It's not one from Jaycar is it?

[Saturn488]

Not sure where it's from. It was a power pack I already had.

Im guessing that the Jaycar ones are no good?

[AdamJL]

Yeah I've had 2 Jaycar 12VDC 10A ones not deliver 12V now. Usually it's somewhere between 11.8-11.9V but sometimes that's enough to stop things working.

These are the duds:
https://www.jaycar.com.au/12v-dc-10a-desktop-power-supply-2-1mm-dc-plug/p/MP3241

A cheaper option from Jaycar, and I've had two of these now (only replaced the first because I stepped on it and broke it!) is this:

https://www.jaycar.com.au/12vdc-7-5a-switchmode-power-supply-mains-to-cigarette-lighter-socket/p/MP3575

uses a cigarette lighter port but it's been rock solid.

edit: about your extension cable though.. how long is it, and what else is connected? First thing to test before spending any money would be to see if you can connect your power supply to another socket and test if it works? Setup the mount indoors and test it out?

[Saturn488]

Great to know thank you! It does look similar to that one at Jaycar the one I have.

It's 20 metres and I have an Intel NUC plugged in as well for my rig.

Yep, I might do just that this weekend. Going to have some rainy weather so it might be a good test to plug it straight on its own and see if anything happens.

Thank you!

[RAJAH235]

20 Metres?
Wowser!
It appears that the extension cable is not adequately large enough to handle the current required.

Too much voltage drop.

Try a larger diameter, higher rated cable.
Make your own?

12 Volts over that distance = Not really efficient.

[AdamJL]

I've run power on 20m cable and it's fine. Depends on the quality of your cable though.

[Dave882]

It’s quite obvious the change in performance in the mount when voltage drops and I’ve always been a bit concerned with undervoltage causing damage to the electronics…so I got one of these things that convert any input voltage between 9-13v up to 13.8v.

https://www.ebay.com.au/itm/Waterproof-DC-DC-Converter-Regulator-12V-Step-Up-to-13-8V-15A-207W-UB3-/384621008664?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=705-154756-20017-0

I’ve been using it on my eq8 and is fantastic when running on a battery that gradually drops in output voltage as the night goes on. The voltage to the mount stays constant till the battery finally dies. I use a similar different unit on my g11 that outputs 18v.

I never share this output to the mount with any other gear. But before all of that, you need to ensure the main supply is delivering enough amps to provide for all the gear with plenty to spare.

[AdamJL]

Yeah buck boosters are a great idea as well

[raymo]

Assuming that the 20m extension lead is a standard 10amp one, Rajah is right, the voltage drop would be unacceptable if the power source is only putting out marginal voltage, say 12-13v. If the source is putting out say 13.5-14.5v then the 10amp lead might suffice. The easy answer is to get 15amp cable as used on caravans, and attach your 10amp plugs to it. The quality of the lead makes very little difference; generally available extension leads use copper wire, and only the diameter of the wire matters.
raymo

[astro744]

Are you running the 230V a.c. 20 metres or the 12V d.c.? The laptop type supplies are typically 100-240V a.c. input so should still be producing 12V out even at the end of 20m of the a.c. run. Measure the output on no load and see what volts you get and then fully loaded. The supply may not be regulating very well so you may need a better one. A booster is a good option but you should still ensure your load is not drawing too much current otherwise you may just need a higher Watts/Amps supply and one that is better regulated.

There are many voltage boost options available at Amazon, eBay and even Jaycar but first ensure Amp capacity is available.

If you are running the d.c. 20m then get heavier gauge cable to reduce the volts drop. A better regulated supply is still preferred.

[mura_gadi]

Do you need all 100 feet of cord? What's the battery for if you have four outlets? Can you run two shorter cords out, both plugged into their own wall socket to share the loading?

[JA]

Skywatcher specifies the power supply requirement for the heq5 as 11 to 15 V at 2 A, although I suspect the current draw may exceed that at higher payloads and high slew speeds. I would look for a good 13.8 Volt regulated supply in order to stay as far as possible away from the 11 volt lower voltage limit.

Best
JA

[Startrek]

I second Adams comments
I’ve used Powertech 7.5amp 12v power adapters for 5 years at two different locations on various mounts , EQ5 , HEQ5 and 2 off EQ6-R mounts and soon to be used on my new EQ8-R mount in June and with 230V extension leads up to 25m long with and without 4 and 5 way power boards and not one has failed yet , all mounts have operated perfectly

Can’t get any better reliable power source to your mount

I use them to power the mount , cameras , dew heated etc...

https://www.bintel.com.au/product/powertech-12vdc-7-5a/

[wasyoungonce]

Chrys


all these simple "brick" converters are usually a little low on the output voltage...aka 11.8V. But the worst thing is the cable out is lets say 22 to 20 gauge at best (narrow gauge and probably not copper wire as well).


Copper wire resistance of 22 to 20 Gauge is at best 16/10 ohms per 1000ft ft =16/1000=.016 ohms per ft x 60 = .96 ohms over your cable....but your cable is there and return to the pwr source so double that rx = 1.92ohms total. Using an online calculator I get 1.973 ohms So I'm close enough.


Voltage is dropped over that cable because it has resistance. Easy to calculate...V=IR. Say you draw 1 amp = 1 x 1.92 = 1.92V lost in the cable. Using the online calc for 20 gauge I get 0.609 ohms over the cable, double for length = 1.2ohms so using above I get 1 x 1.2 = 1.2V dropped over the cable. So the cable and distance matters, it vampire sucks away you usable voltage.



So how much does the system draw...well you have a Mount and power box...so you are drawing at least that in current !


You stated you are measuring 11.1/11.2V....you are lucky to get this!. The Fix....bring the converter closer or use a larger diameter "copper" cable. Most of these converters use small gauge cable and since they come from a place that will use the cheapest parts....they don't even use copper in the cable.


The HEQ5 on its usable voltage range but it says 12-16VDC. So why not use a DC/DC boost converter (https://www.ebay.com.au/itm/312827033805?_trkparms=ispr%3D1&hash=item48d5f1b8cd:g:C80AAOSwrcRdu-cR&amdata=enc%3AAQAGAAACoPYe5NmHp%252B 2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSB 0Xm7k0guzAysaIMfJcbBFqJHWUBl%252BIY ga8A80sSdeYyKWXztXlimkupo3TZzXAWjgx iXJFCcheywGrbYjvQePnGzfspQorte1PxLR ZcOfaFIFFhCz40s97PrcNpJyKXhhvdz4uKF WuPpcrjh32HVwO31g%252BUYvtd1qAUr8gM 6KDvHyuEcJ%252BroGmtk7V%252FN2ulPn9 COQVnjl8imi2YuXt51%252FZLPB6I%252BB aOHYttdzzX8QBMDxRXJhg5N4ukcmKFNU9Pf Ug8m0T%252F05oym8LROcv%252BRGfkSBRC XZjCCWiaJufjtbYlwYKSkjR%252Fvsbt%25 2FbY%252BFyvxZx1fNVTqFn0dScvp5Od1uF buj8M4XaBQ5Ww11Zt%252BqqKtzO71Yte1W quEKYuXF38KDba1eI4Eh0Zm1gQS7eMBiILN 0LaiUIrrIqbDevuCV9MvTyoBpbJ6XxWSsvr l4veJLhiconje5pUxwqbhqefLy5VIOOMQ41 MvhR7hBTnyUqfdD5xwDA%252Fg%252F6%25 2Bp%252Fc5foefOQ2XLVGsKz%252F%252BP Z4C3vdQcv6jZmUeb%252BPNbF%252BrIIIQ lHzWR6oKCTjc2S%252BUFCV3YDwAfhH2l7Q JQBq7eAKk%252BvRw4k4T1E7YdL2v5yFRdF RW1srB%252FDdAMmbfThAwCdnxlcRfGyR%2 52B76w51uiW7x0vokiy9WmHeDLvoQPXu5nD 1K1e0LKHWd9Hh8YGivnCI3oswmoYlz239zY Ovwt1f42yOXPWHymlKyqVoVU9raFsyLpaXC gfqAuigdFIn4zqqrMYUXM8Blql6Khseb8XD z4Q69bOzucCNUifkALLYNCFoY2o1OdAmUMr cG2aKVf%252F11r7rFOKOHfUefrmhVpH4kC mqD7GqZA%253D%253D%7Cclp%3A2334524% 7Ctkp%3ABFBMtujpnOpf). Set it to output 16V DC...it'll be more efficient for the mount and you can negate cable losses.


Of course these are the fleabay ones I'd rather make my own (like the Parallex versio (https://nineplanets.org/12v-to-18v-converter/)n) using LM2587 or LM2588 but its not a cheap exercise . At least I know it would be a good unit and protected.


Hope this helps, the fleabay units work but reports on their reliability are somewhat "iffy"...depends I suppose.

[Saturn488]

OK. This is kind of embarrasing.....

I have set everything back up to do a test and realised I had my power supply plugged into the Adj Out port of the power box and not the 12V DC!!

Thinking back on it I got a feeling I have had it plugged in wrong for a while.

So, I have plugged the NUC and power supply back in the 20m extension cable and getting 12V on idle with no drop and 11.9V when slewing the mount, camera taking subs and cooling and both dew bands on.

Im so sorry, what a stupid mistake. I think I will get a shorter extension cable though cause I don't need 20 metres, prob only need around 8 metres.

[AdamJL]

oh geez, I've heard of Pegasus boxes being destroyed doing that. You're lucky!

This is what I do to prevent that.

[Saturn488]

Brilliant idea, ill do the same.

Thanks!

[RAJAH235]

Hey Chrys,
No probs.
Glad you sorted it out.
Easy to make small errors when fumbling about in the dark. :)

Still....it wouldn't hurt to get a larger gauge (15 Amp) cable, just to be sure.

The references to the type of cable "they" use is thus,
Cheap stuff out of China uses Aluminium strands with a very minute coating of copper.
These will not carry the required current & often fail.

Stay safe.