Celestron 130 SLT help

[smuudge]

Hello everyone. I got myself a Celestron 130SLT earlier this year which I've enjoyed on a number of occasions so far this year.

I have a couple of questions that i wondered if any 130 owners could help with?

First one is battery consumption! It eats batteries for breakfast! So i am thinking of investing in one of these... http://www.amazon.co.uk/dp/B015H2OUA6

The manufacturer has told me the connector/adaptor size is DC 5.5 and the tip is positive current. Will this work with my SLT?

Secondly, astro photography! I really enjoy taking snaps of the moon my only frustration is with my current setup i cannot zoom to view the whole of the moon, i always end up with a crop. My Nikon D3100 is screwed on using the correct Nikon adaptor, i just wondered if there are any other adaptors that will give me more control on the zoom?

Thanks in advance everyone 

[The Thing]

To have less magnification you will need some sort of focal reducer in the optical train.

Most mounts are 12v centre positive, get it wrong and you will fry the mount as they never seem to have any electrical protection. It should tell you in the manual or on the power socket itself. That power pack should do the trick though most people would use a 7ah jump starter with a cigar socket as you have probably got such a lead with the scope. I had something like this for years for my Meade LX90.

The DC5.5 figure refers to the exterior dimension which is probably right for the mount, but the inner hole is critical for a good contact, see this. I can't find a reference anywhere online for the size required. Buying a correct cable and joining it to the output cable of your chosen power pack may be the way to go.
Hope that helps.

[Ivor]

I noticed your battery suggestion only supplies 1A this might not be enough, what batteries do you currently use?

We have bought http://www.amazon.co.uk/Streetwize-SWPP5-Power-Pack/dp/B004ITAF72/ref=sr_1_1?s=automotive&ie=UTF8&qid=1449073082&sr=1-1&keywords=streetwise+power+pack for the club kit the other day. You then buy this http://www.amazon.co.uk/SUNGOLDPOWER-Charger-Cigarette-Compatible-USB-charged/dp/B015C0FB24/ref=sr_1_17?s=automotive&ie=UTF8&qid=1449073300&sr=1-17&keywords=12v+cigar+lighter+adapter+for+usb giving multiple charging points.

[The Thing]

The power tank thingy provided enough juice for fast slewing of the big old Meade forks - it wasn't that RAC but some Maplin supplied unit, £24.99 at the time (2007ish). It could provide 10amps from the cigar socket, 1 amp was the charger which took forever. Your Streetwise unit is an equivalent.

When I got dew heaters I upgraded to a 110AH leisure battery and a CTEK charger.

I no longer use batteries as camp sites always have hookups these days. Now I use 5v from an old PC power supply to power the USB2 hub and the 12v rail for everything else with a step down doobry(ebay) with readouts for the 7.4V DSLR power. In my observatory I now use a 15V laptop supply with a step down doobry for the NEQ6 mount as the PC supply is not man enough when slewing though it was fine with the HEQ5.

However if I go to astro fests in France I will need a battery as they tend to be in the wilds on very basic sites as far as I have been able to ascertain.

Smuudge should go your route though there are cheaper units esp. if planning to take the scope places. I quite like the look of his choice if a suitable lead can be concocted.

[smuudge]

Hi everyone, the main reason for buying the ANNKE unit is the size. I'm keen to get something that sits in the plastic tray and is out of the way. I have dropped the manufacturer a note to see what size the inner dimension of the connecter is before diving in.

Ivor. i only use AA batteries at the moment. nothing external. I simply require something small and portable. The ANNKE unit states 18000mAh, is this not powerful enough then?

[Ivor]

I think the ANNKE is a good product and I complete understand you considering it, my key concerns based on the details on amazon are as follows:

It's unclear from my quick scan of the internet how many amps the mount uses during operation, the ANNKE states a 5V1A output but for the 12V it doesn't specify state it and I'm slightly concerned the 12V output is only for re-charging car batteries so the output amps @ 12V of the device might not be regulated in the same way which might damage your telescope.

Your telescope uses 8 AA batteries, assuming you are using good batteries providing 2500mAh this gives you 12V 2AH. Slewing often requires at least 2-3Amps so a multiple target night would quickly use up your batteries. If the ANNKE can't provide 3Amps @ 12V the mount wouldn't move.

You might also want dew heaters which can required 2A per hour so you will need a peak of say 5A to be pulled from the ANNKE.

I'm not saying the ANNKE isn't going to work, it would be worth contacting the manufacturer to understand how the 12V output works.

I picked the Streetwise because the battery it is held in a robust waterproof case, it will provide enough power to support either an Outreach or Observing session and it can be opened and the battery replaced. The ANNKE is smaller and more aesthetically pleasing if you find out it can support the scope go for it. 

If you are going to manly use the scope on your patio, I'd get a compatible 12V transformer and run an extension lead from the house. If you go to a DSC you'll get mains power so it wouldn't be a problem.

[JohnP]

Its only the 5V USB that is MAX 1A - they advertise that as an emergency car starting battery so it must be able to supply many 10's of Amps albeit for not too long a period at 12V.

[Ivor]

Its only the 5V USB that is MAX 1A - they advertise that as an emergency car starting battery so it must be able to supply many 10's of Amps albeit for not too long a period at 12V.

Correct, what you don't want is 10A going to your mount and there is no indication there are any protections circuits in the device for the 12V output. I've heard the Meade mount don't have a protection circuit in and are often fried without a regulated power supply, I'm not sure about the Celestron but I wouldn't want to take the risk.

There are ways around it but adding additional external fuseboxes negates the advantage of the ANNKE.

There are more qualified members in the club that can confirm the risk, but I'd want to ensure there was sufficient protection between my power and mount.

[JohnP]

Well  a simple 1A (or whatever Max current rating of your mount is) inline fuse would suffice.. Maybe the mount is fused internally..?

[Mike]

Its only the 5V USB that is MAX 1A - they advertise that as an emergency car starting battery so it must be able to supply many 10's of Amps albeit for not too long a period at 12V.

Correct, what you don't want is 10A going to your mount and there is no indication there are any protections circuits in the device for the 12V output. I've heard the Meade mount don't have a protection circuit in and are often fried without a regulated power supply, I'm not sure about the Celestron but I wouldn't want to take the risk.

There are ways around it but adding additional external fuseboxes negates the advantage of the ANNKE.

There are more qualified members in the club that can confirm the risk, but I'd want to ensure there was sufficient protection between my power and mount.

It doesn't matter how many amps go to the mount as long as it can supply whatever max current draw the device has. The device will draw whatever current it needs and no more. 1A or 10A it will draw however many milliamps or amps if it gets that high (perhaps 1-1.5A on max slew) it needs. You can't damage anything by providing too much current under normal operation. You can, however, damage things if you provide too much voltage or if there is a short in the circuit in which case the short will draw a larger amount of current. An unregulated power supply will provide too much or too little VOLTAGE which can cause overheating and excessive current draw. 

However, as John has stated, an inline fuse rated slightly higher than the max current draw is necessary. This will protect the circuit in the unlikely event of a short or other events that causes a rise in current draw. Always choose a fast blow fuse, or even better, if you can find one, a circuit breaker as these are very fast. A fuse will take time before it melts and during that time your circuit is being provided with too much current. The faster the fuse will blow, the less likely anything can get damaged.

[JohnP]

Well explained Mike...

[smuudge]

Thanks everyone. In simple terms what question do I need to pose to the manufacturer please regarding the power output?

I just want to make double sure it will be suitable.
They have confirmed the outer and inner connector dimensions are 5.5/2.1 so fits the SLT 12v input perfectly by my understanding.

[Mike]

So you just need a regulated 12V supply with a rating of about 3Amps.

[smuudge]

Thanks I have sent the manufacturer another email so let's see what they say.

I've stumbled across another alternative. How does this compare to the Ankker above?

Anker® Astro Pro2 20000mAh Multi-Voltage (5V 12V 16V 19V) Portable Power Bank External Battery USB Charger for Tablets, Netbooks, Notebooks, Laptops and Smart Phones -- Compatible with HP, Dell, Acer, Asus, Toshiba Notebooks, Google Glass, Nexus Tablets, iPads, iPhone 6 5S 5C 5 4S, Samsung Galaxy S5 S4, S3, Note 4 3 2 and More https://www.amazon.co.uk/dp/B00BUJCMUQ/ref=cm_sw_r_awd_LXgzwbRB9CGTR

[Ivor]

Based on Mike's comments that looks like a better choice, it will be interesting to see how you get on.