How do you power your mount? Charging "pack" or something else?

[johngwheeler]

Hi,

I'm buying my first powered mount (Celestron AVX) and need to understand my options for providing electrical power. The mount doesn't seem to include any kind of power supply.

The shop I'm buying from suggests a Celestron Charging Pack for $299, which sounds a bit expensive.

I already have a charger for 12V car / motorbike batteries, so I'm wondering whether there is some kind of rig using a car battery that would work on the mount? I imagine the power supply needs to be very "clean" and regulated to work with a mount.

For home use, what do people use to convert 240V AC to 12V? Are the physical power connectors used on EQ mount standard?

Any advice?


Thanks,

John

[Allan_L]

Hi John.
From my experience, most people use a 12v deep cycle battery.
The size you decide upon will depend on what else you power from that same battery, and how long you want to run.

Generally, 17 Ah (Amp/hours) is a minimum, and these are often found in inexpensive Jump starter packs. (see image for example). But even these will be around $100.

If you have several dew heaters powered off it as well, you may need more.

I run a 36 Ah deep cycle battery from Waeco (image2) but it cost me $330.

Have a look at camping places like Rays Outdoors for other options.

[Camelopardalis]

+1 what Allan said, those power tanks from Celestron/SW are really pricey for what you get, there are lots of other options.

A while back I bought a Fusion AGM battery, I got the 55Ah for $180! I got that capacity so that it'd have enough juice to power my scope and dew heater, even my little netbook for a long weekend without any worries. If you search for that type of battery, you'll find many capacities around, just get one to suit your requirements. Assume the scope will use 0.5-1.0A, then another 1-2A for the dew heater, and extrapolate that out for a full night, if that's all you need. It soon adds up :D

I use my battery even when at home, as even the best types of batteries like to be topped up at the wall regularly, so I figure it's a good way to keep on top of that.

[Larryp]

Plenty of good quality AGM deep cycle batteries on Ebay. You need a good multi-stage charger, too.

[bugeater]

I use a big deep cycle battery. I think it's around 70 Ah. I think it was a bit under $200 when I bought it a few years ago. Bought a clip on adapter from Jaycar to provide the cigarette lighter port thing. It weights a lot.

[codemonkey]

I picked up a 105Ah AGM battery recently for... I think $230 from a place in Brisbane. I use that to power my mount and camera, and a separate 27Ah AGM battery to power my dew heaters.

[JoelyE95]

John,

For me at both home and on the field, I use a 350W computer PSU to convert 240V to a stable 25A 12V DC. You can use devoted "Din Rail PSU's", but they are much more expensive. On the field, this is by a 2000W generator as apposed to a wall outlet at home. From there, the 12V goes into a little box that gives me both dew heater control and a few "cigarette" sockets and USB charger for phones and tablets. I have also rigged in a voltmeter for a 9ah battery that only gives me about 4hrs when running my AZ-EQ6 without a generator.

For me, it suits as my generator is quiet and only takes about 0.4L of fuel for about 15hrs. It also (obviously) powers my laptop and any other device I throw at it. It has also lasted me 15 years so far, so I can not complain about longevity.

Joel

[johngwheeler]

OK - I have a trickle charger that (C-Tek), and can buy a deep-cycle car / boat battery.

But presumably I need at least a cable with the correct power terminator for the mount. Are the connectors and cables standard?

Can you just connect the 12V battery directly without any further power treatment (regulator etc.)?

The mount will be a Celestron AVX.

[OzEclipse]

Yes. You can connect direct to a car battery. The mount should come with a car cigarette lighter plug cable.

At any car accessory shop, Super Cheap, Repco etc you can buy a cable with two clamps and a female cigarette lighter socket.
Like this-
http://www.supercheapauto.com.au/online-store/products/SCA-12V-Extension-Socket-With-Clamps-42cm-Lead.aspx?pid=165052&menuFrom=1021628#Recommendations

Just make sure you clip on the correct polarity when you attach it to the battery. Red to positive. Black to Negative. Then plug in your mount.

Joe

[GrampianStars]

Hi John
My portable setup is a 33Ah gel deep cycle battery
Easy to carry and has never let me down
I've added a twin ciga adaptor with a 1.5 lead for convenience, and use a 7amp smart charger to top up before and after use

[DarkKnight]

Hi John

I'm doing the same exercise for my HEQ5.

I've found this one from the UK for $41.17 ... http://www.ebay.com.au/itm/Celestron-3m-power-supply-cable-12V-/280709305706?pt=LH_DefaultDomain_3&hash=item415b94156a

and this one from Hong Kong for $3.08 ... http://www.ebay.com.au/itm/12V-24V-Car-Cigarette-Lighter-Power-Supply-Cord-Adapter-Cable-DC-Plug-2-1mm-Dia-/311354088124?pt=LH_DefaultDomain_15&hash=item487e265abc

I am not at all knowledgeable about things electrical but gee, they look like they do the same thing assuming the plugs are the same. I would imagine you would have to fit an inline fuse with the cheaper job.

[Camelopardalis]

Checkout Jaycar...I bought a bunch of cigarette lighter plug to 2.1mm cables from there that are the same as what Celestron/Skywatcher use. Get one of the guys to check they're centre-positive if you're in any doubt.

[killswitch]

Most cigarette plugs are fused, you just unscrew the tip and a glass fuse will pop out.

As Dunk said Jaycar will have them for $5. I picked one up just last week. No need to spend more than $5 for a simple cable.

The ebay ones will work too. 3M might be a bit too long though.

[DarkKnight]

Apologies if I appear to be highjacking your thread John but as I am possibly asking the same questions as yourself I hope you wont mind.

The specs on my mount nominate a power supply of DC 7.5 to 12v 100mA.
Is 100mA equal to 1A ? If so, what size in line fuse should I use ?

And a bit off topic. I've just done a rough total of my 'portable' astro imaging kit.

HEQ5 mount 9Kg
Tripod 6Kg
Counterweight 5Kg
Camera + lens 4Kg
35AH Gel Battery 14Kg
Total 38Kg
------
Thank gawd they are all individual bits and I have a 4WD to get me right to my set-up location.

[killswitch]

I think your looking at the synscan handset power requirements which is only needed for firmware updates. The handset natively gets its power from the mount

HEQ5 mount power should be similar to the EQ6 which is 11-16v, 4A minimum.

You would use a 5 or 7A fuse.

1000mA = 1A

[DarkKnight]

Thanks Edison.

I did mention before that I'm not a very bright spark with this electrickery stuff. :confused2:

[johngwheeler]

Hi,

I bought a 12V / 7.5 PSU from JayCar to power my Celestron AVX mount (http://www.jaycar.com.au/Power-Products-Electrical/Plugpacks/Desktop---DC-Output/12VDC-7-5A-Switchmode-Power-Supply---Mains-to-Cigarette-Lighter-Socket/p/MP3575), but I am not sure whether it is regulated or not.

The shop staff weren't able to tell me but said "probably", which doesn't fill me with confidence...

It seems to me that having a regulated power supply is highly desirable for a telescope mount, and I'm reluctant to experiment with a $1500 device which specifically states that use of non-Celestron PSUs will void the warranty.

My limited understanding is that a regulated supply should supply the specified voltage for all loads up to the maximum rated current (7.5A in this case). I measured the DC voltage without load at 13.2V - which seems high for a 12V device. The AC "ripple" (measured putting the meter to AC volts, and observing the changes), was 200-300mV. I have read that anything more than 100mV ripple voltage *may* indicate a non-regulated supply.

Can anyone advise whether it would safe to use this PSU on my mount?

Many thanks for any guidance.

John.

[JoelyE95]

John,

When a battery has been taken off the charge, it is generally at that 13.2V mark and gradually drops as it loses charge. The specs of the mount suggest that is needs 12V and 3.5A (full load), so you will be fine with it as a power supply. You would likely see the voltage drop when the load changes (as I do by about 0.2V with 4A of full load for my mount and the same again with heaters on my 25A PSU).

I'd be hoping others here would say the same and instil you with confidence.

Joel

[GrampianStars]

It is a switchmode power supply where the voltage regulation is achieved by switching the pass transistor ratio of on-to-off time.
It'll work ok :thumbsup:

[Camelopardalis]

Any better suggestions for home use? I'm used to using my battery and topping up regularly, but it be nice not to have to lug it down the garden :D

That Jaycar is reasonably priced, is it a case of too good to be true? :help:

[The_bluester]

I have been using one of these in a battery box with an old SLA battery out of a jump start pack wired in with it to float me over any power bumps. I fitted two lighter sockets to the box so I plug in to it directly. I have a multi stage charger that I use to give the SLA the occasional drink between uses.

http://www.jaycar.com.au/Power-Products-Electrical/Power-Supply/Laboratory-Bench/13-8VDC-0-to-12-Amp-Regulated-Power-Supply/p/MP3079

[johngwheeler]

I saw this from http://myastroshop.com.au:

https://www.myastroshop.com.au/products/details.asp?id=MAS-096F

It appears to be identical to the one JayCar sells, so this would seem to be a vote of confidence!

John

[GrampianStars]

Batteries are rated to the number of recharges of recommended discharge e.g.800 times

Gel discharge to 15% x 800
i.e. (100Ah down to 15Ah = 75Ah*800 = 60,000 Ah available usage
SLA/ AGM discharge to 50% x 800
i.e. (100Ah down to 50Ah = 50Ah*800 = 40,000 Ah available usage
Then it only becomes a cost/usage ratio issue on which type to buy

I would use a power supply when home 240V ac is available
a nice all round model
http://www.jaycar.com.au/Power-Products-Electrical/Power-Supply/Laboratory-Bench/13-8-Volt-20-Amp-DC-Power-Supply/p/MP3098

[Bassnut]

oh gaud this hoary monster again. Its crap, its rated for "testing purposes" in the fine print, ie 1 min at full current if your lucky. I roasted 2 before I realised. Its a great smoke generator. Jaycar power supplies are the very bottom of the hobby market, obviously, you pay for what you get. If you must go jaycar, derate the spec by 60% at least.

[sil]

just buy a jump starter power station and be done with it. why muck about with "will this work?" if you dont know what you're doing any want to save a few bucks. you're dealing with electricity outdoors with dew and wet grass and think mucking about with 240V benchtop (indoors, dry) power supplies and random cabling is not a good idea.

[johngwheeler]

I've rather come to the same conclusion! The JayCar 240VAC-> 12VDC PSU doesn't look like a very robust bit of kit, not recommended for outdoor use, and the idea of messing around with 240V supplies at night in damp conditions just doesn't feel right. (I'll use the PSU to power my portable fridge when travelling, or to chill the beers on the verandah :-).

I've bought a 22AH 12V AGM battery which is small enough to sit on the tripod shelf and some cigarette socket adapters.

This will be more portable, less hassle in setting up, and safer. It even adds a bit of extra ballast to the tripod!

John.

[sil]

the tripod ballast is handy, i got a mate to route me a curved triangle board to make a shelf that sits on my cgem dx mount leg supports, handy to keep power pack off the ground and dry, with room to sit other crap safely away from being stepped on in the dark :)

I know the jump start packs are pricey, but they are a also pratical, running laptop off inverter socket, built in light is great to help when setting up or dismantling in the dark when you need both hands. my first goto mount i bought a 10x AA cell holder and a jack to solder to it and ran my tripod off rechargables (got tons of them) with no problems, would give me juice for a weekends viewing then recharge during the week.

Once you progress to a bigger computer mount with a heavy payload and need to also power dew heaters, cameras, etc you need a beefier battery at the center of your power train, but getting started not really, especially if your mount has a battery compartment (just be aware they are usually for alkaline batteries (1.5V each) not rechargeables (1.2V) and you can damage the mount using the wrong ones, external power packs more flexible and cigarette lighter powering is pretty standard so its easy and safe to find a solution. batteries are always heavy and expensive so are portable power solutions.

[DarkKnight]

I've gone the same route as you John with a 36AH Gel battery and a battery box with a ciggie socket and a carry handle. I can sit it under the tripod and also possibly rig up a hook for extra stability if required as you have alluded to.

I'm going to fit a 12v Red LED parking light to the case for illumination.

I also wasn't too fussed with having 240v leads and the PSU sitting on wet grass.

[5ash]

If its the Powertrch 12v, 7.5amp with cigarette socket , I bought one from jaycar 2years ago and it works perfectly. It's the identical make and unit sold in the Bintel catalogue for about $10 more. Bintel advertises it for powering mounts , and other things . I think even cameras. So I think you've got an ideal power supply at an excellent price ( $39)
Regards philip

[The_bluester]

Which is fine given that maxed out I am running at about 25% of the rated output, perhaps some brief peaks at 50% when slewing.

I would suspect heat would be their biggest enemy, the cooling fan is pretty inadequate, I was looking at fitting a much bigger one to aid airflow and reduce noise.