Power issue - CG5 GT mount - too long a power cable ??

[Telescope40]

Hi All. I'm no electrician, but please read on as a bit stuck at the mo.

Bought a CG5 GT mount yesterday from a fellow SGL er. Was seen to be fully working before purchase.

Got home, connected my powertank. Power light is on, handset looks fine. When I go to align I can here the motors go clunk in an attempt to slew, then nothing. Seems to be a lack of power. Couple of Q's if I may.

The cigarette lighter type cable that came with the mount is approx 4.5 meters long. Too long ?? Thinking I am losing power due to this.

I have plugged in my LX90 which has a much shorter ( curled ) cable and it is running fine with no issues. Both need 12v power.

The powertank is not fully charged at the mo. ( currently being charged ).

If the cable length is the issue, is it quite easy to dismatle the cigarette plug, shorten the cable to say 1.5 meters and re attach. Guess a touch of soldering will be on the menu. Hoping not too many bits and bobs drop on the floor when I undo the cigarette plug ?

Any other thorts welcome.

Regards as always John

[cantharis]

Voltage drop = internal resistance X current taken

Internal resistance includes that of all connecting cables - maybe this will help.

[Uranium235]

Try plugging it into a mains power supply to see if it still happens (it needs to be at least 3 amps @ 12 - 13.5v).

[cfpendock]

It is extremely unlikely that the cable is too long. the motors should take less than 1 amp, and so perhaps the cable is damaged or not connecting properly. Can you try the long cable on the Meade? Or can you connect directly to a car cigarette lighter? Otherwise, can you get someone with a multi-meter to check the cable? These tests should confirm the suitability of the cable. I run my celestron CPC 1100 with around 15 metres of mixed lighting cable without a problem.

Chris

[Photosbykev]

These mounts need a minimum of 12v so if your cabling has a small cross section then even with only an amp being pulled it wouldn't take much for the voltage to drop below the minimum required

[Telescope40]

Thanks for the info guys. Think this rules out a cable issue. The same cable worked fine yesterday when the previous owner was giving me a demo, using his 12v power supply. I was just baffled by the fact my LX90 was running fine off the powertank and the CG5 wudddnt.

I'm loathe to switch cables as I blew a goto mount a while ago by cross using a meade cable on a Celestron mount. Not pretty !!

I'm suspecting the powertank now. Its not had much use over the last few months due to the ongoing atmospheric conditions and may well need an overnight / 24 hr charge to get it to somewhere near full output again. If it dont play ball, a new "tank" may be on my to buy list.

Thanks again everyone. This is a cracking site. Always someone happy to help the afflicted.

Regards John .

[cantharis]

This is a cracking site. Always someone happy to help the afflicted.

Regards John .

Yes, I have noticed that there is always a good Samaritan.

[Stu_2011]

Thanks for the info guys. Think this rules out a cable issue. The same cable worked fine yesterday when the previous owner was giving me a demo, using his 12v power supply. I was just baffled by the fact my LX90 was running fine off the powertank and the CG5 wudddnt.

I'm loathe to switch cables as I blew a goto mount a while ago by cross using a meade cable on a Celestron mount. Not pretty !!

I'm suspecting the powertank now. Its not had much use over the last few months due to the ongoing atmospheric conditions and may well need an overnight / 24 hr charge to get it to somewhere near full output again. If it dont play ball, a new "tank" may be on my to buy list.

Thanks again everyone. This is a cracking site. Always someone happy to help the afflicted.

Regards John .

Celestron stuff seems very picky about low voltages. When I purchased my CPC 925 a couple of years ago I also bought a new Celestron power tank at the same time but it never really worked properly, lots of strange slewing movements. I changed the lead acid battery inside the power tank for a better quality lead acid battery (from Maplins) and its been fine ever since

Make sure you charge the power tank once a month, lead acid batteries need to be kept charged up.

Thanks.

Sent from my iPad using Tapatalk

[Telescope40]

Thanks Stu. Didnt realise you could replace the main battery in a powertank. i There is a Maplins near work. I feel a possible visit coming on.

i have one of these http://www.firstlightoptics.com/power/skywatcher-powertank-7ah.html

Is it a case of splittng the case, removing the battery and install a new one. In other words foolproof !!

Would you know which battery I might need if my current charging attempt of my powertank comes up short. .

many thx John

[Telescope40]

Hi Would this be wots required. ??

Maplins Rechargeable Lead-Acid Batteries

7Ah L/Acid Bat 12V MG47B

Order Code: MG47B £39.99

http://www.maplin.co.uk/rechargeable-lead-acid-batteries-27088

Thx John

[Stu_2011]

Hi John

Yes I have this Powertank (the Celestron version but I'm sure they are the same) and yes it was one of those Maplins batteries, it was fairly easy to do but I enjoy doing things like this.

Lots of screws to undo and then the Powertank separates in half and the new battery fits in. I'm sure someone had written a guide on this, I remember reading it before doing mine, I seem to recall 2 hidden screws somewhere?? Under the movable light? A google search will help I'm sure.

Thanks

Stu

Sent from my iPad using Tapatalk

[celkins]

Hi All. I'm no electrician, but please read on as a bit stuck at the mo.

Bought a CG5 GT mount yesterday from a fellow SGL er. Was seen to be fully working before purchase.

Got home, connected my powertank. Power light is on, handset looks fine. When I go to align I can here the motors go clunk in an attempt to slew, then nothing. Seems to be a lack of power. Couple of Q's if I may.

The cigarette lighter type cable that came with the mount is approx 4.5 meters long. Too long ?? Thinking I am losing power due to this.

I have plugged in my LX90 which has a much shorter ( curled ) cable and it is running fine with no issues. Both need 12v power.

The powertank is not fully charged at the mo. ( currently being charged ).

If the cable length is the issue, is it quite easy to dismatle the cigarette plug, shorten the cable to say 1.5 meters and re attach. Guess a touch of soldering will be on the menu. Hoping not too many bits and bobs drop on the floor when I undo the cigarette plug ?

Any other thorts welcome.

Regards as always John

Sorry, John, coming to this rather late.

The cable in question is the one I purchased from FLO with the mount, as a "better quality" power cable - it's a significantly heavier grade of cable than the standard Celestron-supplied power lead, and so should show a lower voltage drop - to be frank, over a 5m length of that at the current the CG5 pulls, you'll hardly notice a voltage drop.

I'd suspect your power tank, as we saw on Saturday... the batteries in power tanks aren't really suited to driving astro-kit: they're designed for a short, high-current pulse to jump start an engine, and they *really* don't like being deep-discharged (say, below 12V).

Cheers,

Carl.

[Telescope40]

Hi Carl. No worries at all. Appreciate your viewpoint. I knew that my powertank would have some issues running the mount, as we saw on saturday morning.

No reflection at all on our transaction. More than chuffed with the mount. Hows the CGE tripod. Still got a smile on my face everytime I think about it. lol

Have given the powertank a long charge. It is running the mount but i cant say its happy about it.

Main question now is recommendations for a new power supply. I'm edging towards one of these. Will it have enough "guts" to be a good buy.

http://www.maplin.co...pstarter-383992

Couple of positive posts on this site. 9ah battery, meter showing charge. Any comments more than welcome. Presume after EVERY use it is critical i charge it back to a full charge ? Charge at least every couple of weeks if not used.

Regards John

[Telescope40]

Other alternatives ??? These two seem beefier !!! 17 ah battery. Thinking the 17ah is aminimum requirement.

http://www.maplin.co...le-power-224871

or http://www.ebay.co.uk/itm/Booster-pack-light-and-12-volt-power-supply-and-compressor-/230867752219?_trksid=p5197.m1992&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D14%26meid%3D3275985499722927205%26pid%3D100015%26prg%3D1006%26rk%3D1%26sd%3D230867752219%26

Thx John

[celkins]

Other alternatives ??? These two seem beefier !!! 17 ah battery. Thinking the 17ah is aminimum requirement.

http://www.maplin.co...le-power-224871

or http://www.ebay.co.u...d=230867752219

Thx John

Hi, John,

- didn't mean this to sound too heavy, sorry if it came over that way: I'd intended it as more of a technical explanation as to why I picked that lead than anything else - I'd read that the standard leads can be a bit like wet string.

The first one you referenced in the 7:49 post is exactly the same one as I grabbed on Saturday morning; in my experience, you'll get at least a couple of hours out of one of those for visual work with the CG5 (ie not running a camera, too), more likely 3-4, and if you take care of its charge state, you may well get a couple of years service (don't run it down too far - I found the mount really doesn't like it once the voltage reading drops below about 11V, and that's probably significantly shortened its service life, too) - not bad for £25!

Personally, I think the second one (Maplin) is way over priced - you can pick up the same for less, as you see from ebay.

IMHO, once you get towards the £50 mark, you're getting to the lower end of significant capacity, deep-discharge tolerant leisure batteries, and for the way we (Astronomers) use them, that really is the right type to go for, but it comes at the higher cost by the time you've packaged the supporting bits (box, voltmeter etc.) - I'll try to get the pictures of my battery box build uploaded next week.

Glad to hear you're getting on well with the mount - I've yet to figure out how to cart that tripod around with me, but it'll build my muscles up :-)

Clear skies.

[allcart]

I have one that looks like the one in the ebay link but without the compressor. It is the 17ah model and has run my CG5-gt without a problem. The longest run has only been about 3 hours. I think I could comfortably power my dewstraps as well from this unit.

[Telescope40]

Hi Carl. No problem. Your comments not heavy at all. No offence taken. Really enjoyed our chat on Saturday. I know now which power supply you were running so Maplins it is this week, when i get an hour or two.

Thanks to all again with the advice and wisdom.

John

[Telescope40]

One last time guys . Which would you reccomend. Seem to be almost identical apart from air compressor on the 2nd one for £39.99 AND the cheaper one has a 9AH battery, the second has a 17AH battery.

1. http://www.maplin.co.uk/3-in-1-portable-jumpstarter-383992 9 ah battery

2. http://www.maplin.co.uk/portable-jump-starter-and-air-compressor-49038 17 ah battery.

Is it worth spending the extra and going for the 17 ah option - much better performance ??

Thx john

[DrRobin]

Hi,

I run an eq6 from a 12V 7AHr battery with a heavy scope for ages, no problem at all. I don't use a power tank just buy my batteries from here

http://www.rapidonline.com/Electrical-Power/Yuasa-Batteries-Rechargeable-Lead-Acid-62268

The 12V 7Ahr is £13.63 + VAT and delivery, but is currently out of stock. The do stock bigger batteries if you want more capacity. Delivery is free if you end up spending over £35. We use Rapid at work for many years always been very good, fast and 100% reliable.

Yuasa are one of the best makes of sealed lead acid batteries and they will give many years of good service. I don't bother with a power tank, just connect a cable (which I make) straight on to the terminal with a couple of crimps, but best to put an in-line fuse in there. All of my cables are less than 2m long and I usually use reasonable heavy duty wire, say about 0.5mm², which would be fine up to a couple of amps.

Rapid also sell molded power leads and cigarette lighter plugs, leads and distribution boxes if you need them? Cig plugs have an inbuilt fuse. I would think Maplin also sell all of this kit.

[nightfisher]

Yes better to get the larger battery, i have just bought a 26 amp hour battery for £15 from local scrap yard, he has a job lot, tested and ideal!

quick question, so i dont blow the HEQ5 up: can some one clarify the connection, i think its "tip positive", could some one elaborate on this please

[barkis]

I have a CG5-GT Pro mount too, and use it with a 20 metre long power lead plugged into a Maplin power tank 17A/H Cap. battery.

No issues ever with supply problems. I always ensure the battery is adequately charged

Power tanks can be unreliable if in regular use, and not replenished sufficiently after a session.

The voltage meter reads the voltage when you press the button to activate it, but do check the voltage whilst the drive is in use.

A 13volt open circuit reading, can fall off dramatically when a load is applied.

Erratic mount behaviour can attributed to low volts in most instances.

Ron.

[Telescope40]

Hi Guys. I'm back. I've shelled out for one of these. http://www.maplin.co.uk/portable-jump-starter-and-air-compressor-49038 Seemed a good choice.

Any tips now please. Initial instructions with the charger is to fully charge over a period of 15 hrs. This has been done and mount is functioning. Do I need to do a "few more" 15 hour charges over the next few days to get it to an "optimim" state. ??

Would an overnight charge every weekend be the way to go so it's always available if and when this cloud ever decides to clear.

Any sage advice greatly received. John