Longer cable to connect SWSA GTi to battery

[a6400]

Hi,

According to Skywatcher manual:

”The Star Adventurer GTi can also be powered using a 12V DC source. You
can utilize an AC/DC power transformer if you want to plug into a wall outlet.
Make sure that the power supply used has an output of 12V at 2 amps and
2.1mm center pin positive - 5.5mm length.”

 

The battery I have:

https://www.amazon.co.uk/gp/aw/d/B082X92J72?psc=1&ref=ppx_pop_mob_b_asin_title
 

I have found a cheap long cable but the one that came with battery and seems to work fine (too short) has kind of hole on sides.

https://amzn.eu/d/3jNp1ay
 

Here is the original cable: 

https://imgur.com/a/YZVFMNB

 

Thanks in advance

[Carbon Brush]

The short and poorly checked answer is that it should be OK.

The correct (but not immediately helpful) answer follows.

The Skywatcher user manual (and CE/UKCA approval documents) should state max/min voltage for correct operation.
All these must be available from the importer (a legal requirement) if not supplied with the equipment.

The Talentcell user manual (not a few bits of text on the amazon web site) should state the output voltage range in normal operation.
Also their approval documents should contain this information.
Ensure the upper end of voltage (at full charge) supplied does not exceed that allowed by Skywatcher. Very important!
If the lower end falls below that allowed by Skywatcher, monitor voltage when in use and be prepared to end use early.

Kenable are a well known cable manufacturer.
The long answer is to identify the Kenable part number and check the spec on their web site.
The cable CSA or resistance will be specified.
That allows you to calculate exoected voltage drop.
Provided it is small (which I expect) it can be ignored.

All of the above is applicable to any mount, power supply and lead combination. Not just this enquiry.
With the caveat that if a heavy off balance scope and big mount are involved, slew currents will be higher than expected.

HTH, David.
 

[Celerondon]

Yes, that longer DC5521 male/male cable will work.  Like David said, the numbers need to be right but you aren’t doing anything extraordinary.   That LiFePO4 battery pack will naturally produce voltage in the range that your mount requires with current to spare for other devices.   As long as your cable runs don’t exceed two meters you should be fine. 
 

Don

[a6400]

44 minutes ago, Carbon Brush said:

The short and poorly checked answer is that it should be OK.

The correct (but not immediately helpful) answer follows.

The Skywatcher user manual (and CE/UKCA approval documents) should state max/min voltage for correct operation.
All these must be available from the importer (a legal requirement) if not supplied with the equipment.

The Talentcell user manual (not a few bits of text on the amazon web site) should state the output voltage range in normal operation.
Also their approval documents should contain this information.
Ensure the upper end of voltage (at full charge) supplied does not exceed that allowed by Skywatcher. Very important!
If the lower end falls below that allowed by Skywatcher, monitor voltage when in use and be prepared to end use early.

Kenable are a well known cable manufacturer.
The long answer is to identify the Kenable part number and check the spec on their web site.
The cable CSA or resistance will be specified.
That allows you to calculate exoected voltage drop.
Provided it is small (which I expect) it can be ignored.

All of the above is applicable to any mount, power supply and lead combination. Not just this enquiry.
With the caveat that if a heavy off balance scope and big mount are involved, slew currents will be higher than expected.

HTH, David.
 

I know nothing about electricity but that battery was recommended in few places for multiple mounts including mine.

[a6400]

9 minutes ago, Celerondon said:

Yes, that longer DC5521 male/male cable will work.  Like David said, the numbers need to be right but you aren’t doing anything extraordinary.   That LiFePO4 battery pack will naturally produce voltage in the range that your mount requires with current to spare for other devices.   As long as your cable runs don’t exceed two meters you should be fine. 
 

Don

So the cable I’ve linked will work despite the output/input looking slightly different?

And I should go for the 2m length?

 

[symmetal]

21 minutes ago, a6400 said:

So the cable I’ve linked will work despite the output/input looking slightly different?

And I should go for the 2m length?

 

The cable will work despite the ends looking different. They both perform the same function.

The Kenable site just specifies 75W rating for the cable used, no other details, which isn't very helpful without specifying the voltage it's used with. I expect it's nominal 3A cable so will drop some voltage when the mount is slewing depending on the cable length. The current used determines the voltage drop down the cable. The Star adventurer doesn't take much current so if you can use a 2m cable then fine, but if you need 3m to make things easier to work with choose 3m length. It's very unlikely to cause any problem.

Alan

[a6400]

8 minutes ago, symmetal said:

The cable will work despite the ends looking different. They both perform the same function.

The Kenable site just specifies 75W rating for the cable used, no other details, which isn't very helpful without specifying the voltage it's used with. I expect it's nominal 3A cable so will drop some voltage when the mount is slewing depending on the cable length. The current used determines the voltage drop down the cable. The Star adventurer doesn't take much current so if you can use a 2m cable then fine, but if you need 3m to make things easier to work with choose 3m length. It's very unlikely to cause any problem.

Alan

I can ask the seller for more details, should I just ask about voltage?

Or perhaps you can link a different cable that you are sure will work?

I really don’t want to fry the motherboard haha

[Bivanus]

Hello, C&I eng here , so maybe a bit biased due to use of professional equipment... When going to Kenable site , they are fair enough to provide the actual model number of the cable. In your case is PPW00027 for the 3 meter variant, so take that , put it in Google and see the sad truth. I downloaded the pdf spec from Farnell site , those guys are rather correct on their data. You might want to try a thicker cable if you aim for 3A. 

PPW00027.pdf

[a6400]

Hard to find something thicker, maybe this one? 
But it’s 1m only

 

https://amzn.eu/d/hQrwtCG

[Bivanus]

The issue is that , sadly, it's the plastic that's more often thicker , not the cooper part. I usually make my own , 2.5 mmp speaker cable , black&red or black&black with red stripe. Also , I go to telecom shops and get CCTV supply cables if they have them 😁 ( 3.3 mmp for some reason , I suspect the gauge used is in imperial  units)

In that idea , Mr. Goagle found me this site , look's like is UK based https://www.blackcatcables.com/ , they have address and phone and seem to be brick and mortar based. Al least a call to ask about the wire gauge for 2 - 3 Amps can't hurt. They should also have an idea regarding voltage drop. Of course , it's 2024 so they can also simply resell stuff from the magical east 😅

EDIT: Looking up the gauge , I saw that 8 Gauge is 0.1285" or 3.264mm and 10 Gauge is 0.1019" or 2.588mm. The more you know...

EDIT 2 : No , no sad face , there is always Option 2 - buy a cable you like and try it. The chances of actually breaking something with this are slim , worst case scenario the cable wil be a bit hot when higher A , but you don't have big Amps constantly on it.

Edited February 4 by Bivanus

[symmetal]

1 hour ago, a6400 said:

I can ask the seller for more details, should I just ask about voltage?

Or perhaps you can link a different cable that you are sure will work?

I really don’t want to fry the motherboard haha

No, the voltage used is confusing the issue here and isn't relevant to you. Kenable quoting a watts rating is rather meaningless on its own. I've bought several of the same multicomp pro cables from Farnell as linked by Bivanus and their 0.6A rating is rather conservative I would say. Current rating is dependant on where it's used, and is governed by the rise in cable temperature when in use, to prevent fires. In the open air the current rating is much higher than if was enclosed in a bundle of wires. If they specified the actual cable size in AWG (American Wire Gauge) or CSA (Cross Sectional Area) we could say exactly how it would perform, but unfortunately that's missing from all the sites data.

Amazon used to sell plenty of thicker higher current cables with the same 2.1 x 5.5mm male connectors but they are not available anymore.

I've looked through my cables bin and found an identical 3m Multicomp Pro DC power cable. I've measured it at 0.3 ohms resistance per wire. At 2A current it will drop 1.2 volts. The Star Advenurer GTI spec states 8AA batteries (DC 9.0 to 12.6V) or a 12V external supply. The Star Adventurer will actually draw less than 2A as the supply is always rated higher than the max current drawn. If it however, did draw 2A then the mount will have an input voltage of 10.8 volts. This is significantly higher than the minimum required, so I can't see any problem with using the 3m Kenable cable in real life.

You won't fry the motherboard if the input volts are too low, so don't worry about that. 🙂

Alan

[a6400]

2 hours ago, symmetal said:

No, the voltage used is confusing the issue here and isn't relevant to you. Kenable quoting a watts rating is rather meaningless on its own. I've bought several of the same multicomp pro cables from Farnell as linked by Bivanus and their 0.6A rating is rather conservative I would say. Current rating is dependant on where it's used, and is governed by the rise in cable temperature when in use, to prevent fires. In the open air the current rating is much higher than if was enclosed in a bundle of wires. If they specified the actual cable size in AWG (American Wire Gauge) or CSA (Cross Sectional Area) we could say exactly how it would perform, but unfortunately that's missing from all the sites data.

Amazon used to sell plenty of thicker higher current cables with the same 2.1 x 5.5mm male connectors but they are not available anymore.

I've looked through my cables bin and found an identical 3m Multicomp Pro DC power cable. I've measured it at 0.3 ohms resistance per wire. At 2A current it will drop 1.2 volts. The Star Advenurer GTI spec states 8AA batteries (DC 9.0 to 12.6V) or a 12V external supply. The Star Adventurer will actually draw less than 2A as the supply is always rated higher than the max current drawn. If it however, did draw 2A then the mount will have an input voltage of 10.8 volts. This is significantly higher than the minimum required, so I can't see any problem with using the 3m Kenable cable in real life.

You won't fry the motherboard if the input volts are too low, so don't worry about that. 🙂

Alan

Okay I went with the first linked cable but 2m. 😁

[symmetal]

I bet that was a more drawn out discussion than you were expecting. 😃 Your 2m cable will be fine.

Alan

[Carbon Brush]

Yes a drawn out discussion.

I took a look at the Talentcell specification and user manual (attached) and it will provide 14V on full charge.
This is OK for the majority of mounts and accessories. The 5A capability is good for big mounts and off balance loads.

The Skywatcher site was particularly useless at providing a manual - linking me to manuals for 5V powered products!
However, Mr Google came to the rescue.
https://www.manuals.co.uk/sky-watcher/star-adventurer-gti/manual
Note that the table on page 2 indicates maximum supply 12.6V. Lower than the Talentcell delivery with decent charge.
Current consumption is not given. But common sense says it will be easily within the Talentcell capability.

Yet another case of Skywatcher providing sketchy and incomplete product specifications. not just electrical, their optical specs are just as vague.
Yet we keep handing over hundreds of pounds for their kit?

HTH, David.

 

 

 

lf4100-user-manual.pdf

[a6400]

On 05/02/2024 at 15:38, Carbon Brush said:

Yes a drawn out discussion.

I took a look at the Talentcell specification and user manual (attached) and it will provide 14V on full charge.
This is OK for the majority of mounts and accessories. The 5A capability is good for big mounts and off balance loads.

The Skywatcher site was particularly useless at providing a manual - linking me to manuals for 5V powered products!
However, Mr Google came to the rescue.
https://www.manuals.co.uk/sky-watcher/star-adventurer-gti/manual
Note that the table on page 2 indicates maximum supply 12.6V. Lower than the Talentcell delivery with decent charge.
Current consumption is not given. But common sense says it will be easily within the Talentcell capability.

Yet another case of Skywatcher providing sketchy and incomplete product specifications. not just electrical, their optical specs are just as vague.
Yet we keep handing over hundreds of pounds for their kit?

HTH, David.

 

 

 

lf4100-user-manual.pdf 371.93 kB · 0 downloads

I remember thinking about buying one of their Dobsonians and there was no info anywhere on how large was the mount, so couldn’t figure out if it would fit in the car, ridiculous.

More ridiculous is the design of the polar scope cover. If you insert 8x AA batteries into GTi, the plastic cover that secures batteries won’t align properly, and the scope cover keeps falling off, you can barely touch it and it falls off.

Remove batteries and it holds properly… 😂

Apparently there was the same issue in previous version so they knew it has failed design…
 

On the other hand I don’t know if all the Chinese companies are much better…

Edited February 6 by a6400

[Carbon Brush]

9 minutes ago, a6400 said:

If you insert 8x AA batteries into GTi, the plastic cover that secures batteries won’t align properly, and the scope cover keeps falling off, you can barely touch it and it falls off.

Gaffer tape and elastic bands to the rescue🤣

 

[a6400]

Just got the cable and it fits the mount but doesn’t seem to fit the battery.

 

Got this one instead

https://amzn.eu/d/4gGWwFr

Edited February 7 by a6400

[symmetal]

You possibly may need to push it a bit harder to plug it into the battery. As seems to be the case throughout this thread the actual specifications that matter are missing from the components themselves.

The TalentCell manual page calls the 12V in/out connector a DC5521 which 'implies' a 2.1mm pin diameter and 5.5mm width outer diameter. The plug with the two inner prongs rather than the round inner connector as on the Kenable can likely be forced over a pin which is slightly larger. The two pin sizes in 5.5mm width DC connectors are 2.1mm or 2.5mm, with 2.1mm being the most common. Enlarging the picture on the TalentCell manual and measuring with a ruler it looks to be 2.1mm if the outer diameter is taken as 5.5mm so the Kenable cable should fit. Try again using a bit more force. A tight connection is better than a looser one.

Alan

[a6400]

1 hour ago, symmetal said:

You possibly may need to push it a bit harder to plug it into the battery. As seems to be the case throughout this thread the actual specifications that matter are missing from the components themselves.

The TalentCell manual page calls the 12V in/out connector a DC5521 which 'implies' a 2.1mm pin diameter and 5.5mm width outer diameter. The plug with the two inner prongs rather than the round inner connector as on the Kenable can likely be forced over a pin which is slightly larger. The two pin sizes in 5.5mm width DC connectors are 2.1mm or 2.5mm, with 2.1mm being the most common. Enlarging the picture on the TalentCell manual and measuring with a ruler it looks to be 2.1mm if the outer diameter is taken as 5.5mm so the Kenable cable should fit. Try again using a bit more force. A tight connection is better than a looser one.

Alan

I would need to put a lot of force to be able to fit it in, or damage the input/cable.

We'll see how the new cable does.

[a6400]

The new cable works fine. 🙏

[symmetal]

Good to hear. 🙂

Alan