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#1 sonny.barile

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Posted 21 July 2014 - 11:38 PM

What is the current draw of the 6/8se mounting? I remember reading in the manual that it was 750ma but I am not sure if that is peak or average. I assume it is drawing more when slewing than while tracking.

#2 Star-gaze69

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Posted 22 July 2014 - 07:05 AM

Per the manual it is:
12VDC-750 mA (Tip positive)
Tip positive? What is that? :confused:

#3 mclewis1

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Posted 22 July 2014 - 07:32 AM

750ma is likely the amperage draw with one motor slewing at high speed.

Just tracking the mount will only draw a few hundred ma. I know a few folks who have modeled their SE's power consumption (for sizing a battery) using 500ma average draw (occasional horizon to horizon high speed slews and then just tracking the rest of the time). 500ma seems to work well as an average conservative number.

"Tip positive" is a very important piece of data if you are building your own power source or planning on using a 3rd party product. Tip positive tells you the polarity of the plug (center pin is positive, outer case is negative). Getting this wrong will ensure that you'll need to return the scope to Celestron for repair (or be replacing one or more boards yourself). Fortunately most DC power products available today (batteries, AC power supplies, etc.) are usually wired "tip positive".

#4 sonny.barile

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Posted 22 July 2014 - 08:23 PM

Thanks I am researching lithium jump packs. Most come with a saftey regulator that turns off the power if the draw goes over 2 or 3 amps. I didnt think the SE mount would draw that much but I wanted to be sure. However, my research in to these lightweight power sources is that most of them do not truly meet the 12v they advertise. The majority are made up of (3) 3.7v batteries. From what I understand, the 11.1 volts wont run the SE.

#5 philippe44

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Posted 22 July 2014 - 09:43 PM

11.1 runs the SE - I've done a mod to my SE and integrated internally a 2x3 LiIon pack with a charger and it works perfectly (see http://www.cloudynig...6619633/page...

#6 hamdul

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Posted 22 July 2014 - 09:48 PM

Philippe,
Tell me more of what you have and where you got it?
Thanks,
Fred

#7 philippe44

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Posted 23 July 2014 - 01:33 AM

In the link above, I explain all I've done. Basically, I put inside my 8SE a pack of 6 Li-ion cells, in replacement of the batter compartiment. Then I've created a new interface board, replacing the existing one (the one that has the RJ connectors for AUX and AG) and on that new board I've added a li-ion charger. With that, I now have a 8SE fully autonomus for many hours (5200 mA) and I can just plug the normal plug during the day to recharge it - like a small evolution before the evolution ;-)

#8 Arctic_Eddie

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Posted 23 July 2014 - 06:11 AM

A LiPo 3S pack works fine in the SE mount.

http://www.cloudynig...d=nexstar&am...

#9 sonny.barile

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Posted 23 July 2014 - 06:19 PM

This is what I was thinking about getting. It is turnkey because it has a 2.1mm connector.
http://www.amazon.co...tors/dp/B009...

#10 sonny.barile

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Posted 23 July 2014 - 07:24 PM

Well....I took the plunge and ordered it. I will review it when it comes next week. If it doesnt work for my 8se, my wife will have a very nice back up power supply for her I-Phone.....

Any battery guru's see possible issues with this set-up?

#11 sonny.barile

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Posted 26 July 2014 - 04:40 PM

I received my package today. I charged it fully and it is ready to go. As I mentioned before it is a turnkey solution as it has a cable that terminates in a 2.1mm connector which will mate appropriately with the SE mount. The plug is rather short at 28 inches but I plan on mounting the battery over the onboard battery compartment which will rotate with the mount. I placed it in that position and checked to see if the tube coupled with the diagonal and an eyepiece would clear. It did so successfully. (See the pics below) The power bank is just a little larger than an average smartphone.

My first impression from playing with it in the house is that it supplies power to the mount as it should. However this is not a meaningful test. I will try to get out tonight or tomorrow to put the scope through some hours of use to see how this power bank holds up. It is rated at 10000mah and has 2 usb ports for charging smart phones and a dc line that is switchable between 9 and 12 volts. I switched the supply to 9v and this still seems to supply enough power to slew the scope.


The battery and a slew of power and connector options.
Posted Image


The proposed mounting area.
Posted Image


Clearance.
Posted Image



Regards
Sonny

#12 hazilim

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Posted 26 July 2014 - 10:07 PM

Sonny:
I've got an essentially identical setup to yours, but using a 10-cell (AA) NIMH flat pack: Pack attached to the battery compartment top with velcro, short cord that terminates in a 5.5mm / 2.1mm power plug. It's a truly perfect setup.
But the NIMH pack is rated for only 2000mah, whereas the Li-based battery systems, such as yours, are rated at FAR greater capacity.
My 2000mah battery pack easily drives the 8SE in slewing & tracking (no dew heater) for 2+ hours. I would expect your setup to be capable of powering the mount for 10 hours. This means that you can also power a light & a dew heater & still be able to observe for many hours on end. And the price is awfully tempting.
Well done! Please keep us posted on your setup.
Bob

#13 Midnight Dan

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Posted 27 July 2014 - 09:38 AM

Hi Sony:

Just want to mention that the 10 amp hour (10000mah) rating of your battery is NOT comparable to a 12V battery, and your capacity at 12V will be much less.

We tend to think of amp hours as a universal measurement of the capacity of the battery, but it is not. It is rated at a specific battery voltage. For example, a 6V battery that has 10 amp hours has the exact same capacity as a 12V battery that has 5 amp hours. We tend to ignore voltage because we're usually talking about 12V batteries so it's assumed that the rating is at 12V.

The problem with these lithium multi-purpose battery packs is that they have several output voltages. Since the lowest voltage makes the battery look the best in terms of amp hours, that's where they rate the amp hours. In your case, they are probably rating it at 5V, not 12V. So at 5V this battery has a 10 amp hour rating, which means at 12V it has about 4 amp hours (4000mah).

That's still pretty good, but just wanted to be sure you weren't expecting 10 amp hours of capacity at 12V.

-Dan

#14 sonny.barile

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Posted 27 July 2014 - 10:28 AM

Dan

You are correct in your assumption. The battery is rated at 37wh. The 10000ma was calculated at 3.7v This will give me 3ah at 12v. I was using rechargeable nizn batteries in the onboard compartment that were rated at about 1.5a and that gave me about 2.5 hours of use. I would assume the new pack will give me approximately double that.

#15 Midnight Dan

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Posted 27 July 2014 - 12:00 PM

:waytogo:

By the way, I just noticed this in your previous post:

>>I switched the supply to 9v and this still seems to supply enough power to slew the scope.

That's excellent! They must be making the newer mounts with more tolerance to low voltage. Mine will not run at all at 9 volts.

-Dan

#16 sonny.barile

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Posted 27 July 2014 - 03:57 PM

That was only in the house Dan. It hasn't been put to the real test yet. Im not sure if the "go-to's" will be accurate or if the mount will get skittish as when the batteries go dead. .....But if it does work, portable power banks with switchable feed can last a little longer. In my case it goes from 3 to 4ah capacity. Philippe44 posted that he had the mount running at lower voltage (11.1v). You should check out his link....It is quite interesting. He built in a rechargeable power source.

#17 mich_al

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Posted 27 July 2014 - 05:34 PM

I have no idea what the elecronics in these mounts are but unless the spec calls out these lower voltages as kosher then I would not run the mounts at them. Controller boards are generally expensive and often require a trip to the mfg for troubleshooting/replacement. Check the spec and don't play with fire.

#18 Sarkikos

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Posted 27 July 2014 - 05:45 PM

:waytogo:

By the way, I just noticed this in your previous post:

>>I switched the supply to 9v and this still seems to supply enough power to slew the scope.

That's excellent! They must be making the newer mounts with more tolerance to low voltage. Mine will not run at all at 9 volts.

-Dan


My new NexStar SE 6/8 mount runs fine for at least four hours with a C6 on board. That's from eight 1.2v 2450mAh AA rechargeable batteries. It would probably run longer, but that's the longest I've had the NexStar out here at home. When I check the batteries the next day, they're still in the green.

I was thinking about ordering one of these more powerful battery packs suggested in this thread and in another. But if it ain't broke...

When I'm at my dark site, I always have the NexStar plugged into my Orion Pro 17 12v 17Ah portable power supply. I keep fully charged AA's in the NexStar battery compartment just in case.

I haven't seen any difference in slewing, goto accuracy or tracking between the Orion Pro and the onboard AA's.

Mike

#19 sonny.barile

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Posted 27 July 2014 - 07:08 PM

Al
Going lower voltage may not work in some cases but it wouldnt fry anything.


Mike
How old is your mount? My se is about 4. Maybe Dan was correct in his assumption that they got the electronics dialed in.

#20 Sarkikos

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Posted 27 July 2014 - 07:26 PM

Mine is only a month old. Maybe the newer NexStars did finally get it right.

Mike

#21 mich_al

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Posted 27 July 2014 - 10:32 PM

Al
Going lower voltage may not work in some cases but it wouldnt fry anything.


and how do you know that?

#22 mclewis1

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Posted 27 July 2014 - 11:32 PM

Celestron goto mounts will generally work fine with voltages from around 10.5 up to 15. The HC and MC boards have voltage regulators on them which allows them to work in a range of supply voltages. When voltages start to drop below the mid 10s the mounts seem to start to "loose their minds". You get slews occasionally going past objects or off into different directions. If the voltage stays down in the low 10s you'll usually start to see the "No Response" 16/17 errors and then you'll have to perform a new initial alignment. With very low supply voltage you'll get the No Response error immediately on power up, the mount won't work but it won't be damaged.

The high speed slew is when the mount draws the most amperage, and with a low battery or undersized power supply that extra amperage draw will become a decrease in the supplied voltage. This is why folks often first notice a low battery when they do a goto slew to an object. When you are doing an initial alignment on a low battery it can appear that everything is working fine at power up and then after you've slewed to a few alignment stars the mounts starts to overshoot or the No Response errors show up.

#23 Sarkikos

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Posted 28 July 2014 - 06:07 AM

Celestron goto mounts will generally work fine with voltages from around 10.5 up to 15. The HC and MC boards have voltage regulators on them which allows them to work in a range of supply voltages. When voltages start to drop below the mid 10s the mounts seem to start to "loose their minds".


This is bizarre since the mounts are designed to be used with eight 1.2v AA batteries, giving a total voltage of only 9.6v, well below the mid 10's.

Mike

#24 Sorny

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Posted 28 July 2014 - 08:01 AM

Celestron goto mounts will generally work fine with voltages from around 10.5 up to 15. The HC and MC boards have voltage regulators on them which allows them to work in a range of supply voltages. When voltages start to drop below the mid 10s the mounts seem to start to "loose their minds".


This is bizarre since the mounts are designed to be used with eight 1.2v AA batteries, giving a total voltage of only 9.6v, well below the mid 10's.

Mike


No, 12V off of 8 AA 1.5V batteries.

#25 Sarkikos

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Posted 28 July 2014 - 08:04 AM

I could have sworn that my AA's say "1.2v." Well, I do need new glasses. These are NIMH rechargeables. Are some 1.2v and others 1.5v? I want to use rechargeables, not throwaways. You can tell I'm not an expert on batteries.

At any rate, the batteries I'm using in the battery compartment work fine for at least four hours. No problem. But I'm only using them to run the NexStar, no dew busters or anything else.

Mike






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