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Teabagger
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Reged: 08/18/12

Power Source question.
      #5376851 - 08/20/12 12:36 AM

So I recently got a a 5se, very pleased with the scope. I hear power is an issue without a powertank type device. I was wondering about operational voltage ranges for accuracy. I was thinking of just using a Deepcycle Marine battery.
Im sure somoene around can share some light on this. Also if this has been addressed in other posts I sincerely apologize.


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Tel
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Reged: 03/31/06

Loc: Wallingford England
Re: Power Source question. new [Re: Teabagger]
      #5376981 - 08/20/12 03:34 AM

Hi Teabagger,
Welcome to CN and to this nexstar forum !

Yes, a good power supply to these 'scopes is indeed critical and you will soon find that if you rely on even a fully charged set of AA batteries their ability to drive your 'scope will be limited: probably only to two to four hours depending on the use to which you put your 5SE. Worse still, is any attempt to power your 'scope with "rechargeables" which only prove a nominal 1.2V per cell rather than 1.5V.

Thus, popular choices are of course the Celestron branded 17Ah and 7Ah Power Tanks, although they come at a "brand name" price. Alternatively, ca. 20Ah automotive jump start batteries or AC/DC mains transformers are also favourites.

However, I believe a Deep Cycle Marine battery to be an excellent source. Have a word perhaps, (drop him a PM), with our CN member, brianb11213. As far as I recall, he uses or has used one very successfully as an enduring source of power.

Best regards,
Tel


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Arthur Dent
Galactic Hitch-Hiker
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Reged: 10/23/08

Loc: South Yorkshire, UK
Re: Power Source question. new [Re: Tel]
      #5377017 - 08/20/12 04:37 AM

Hi Teabagger,

First a warm welcome to the forum - a place many of us consider to be 'home'.





Secondly, I am presuming that your deep-cycle marine battery is a 12V unit? If so, it should be OK for the task providing the capacity (Ah) is sufficient - especially if you plan to run some anti-dewing equipment at a later stage. The 7Ah Celestron PowerTank is adequate for plain tracking but if you run anti-dew equipment then you'll need at least 12-15Ah.

If you are making your own lead, make sure you get the correct 5.5mm dc power plug. The one for the Celestron is not as common as that used by Meade (they have different internal diameters). You can use a Meade plug in a Celestron unit - but the fit will be sloppy and you may have intermittent problems. The Celestron power plug will not fit into the Meade unit.

ENSURE that the centre-pin is positive and the outer sleeve is negative. These scopes have no reverse-polarity protection and you'll fritz the scope's electronics if you don't!

The following picture will probably explain it better:



Hope this helps,

Art


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brianb11213
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Re: Power Source question. new [Re: Tel]
      #5377029 - 08/20/12 05:02 AM

Quote:

However, I believe a Deep Cycle Marine battery to be an excellent source. Have a word perhaps, (drop him a PM), with our CN member, brianb11213. As far as I recall, he uses or has used one very successfully as an enduring source of power.



There's really no difficulty in using a deep cycle battery other than arranging the power lead and lifting the damned thing. My large capacity battery is HEAVY. So long as it is 12V nominal it will be OK.

The easy way is just to cut off the cigar plug connector on the cables & use croc clips instead to attach the power cable direct to the battery but you MUST be careful to get the polarity right as there is no reverse polarity protection circuitry in the mount & if you connect it the wrong way round the mount electronics will be destroyed. Check with a multimeter that you have the positive terminal of the battery connected to the centre pole of the connector before you plug it in.

The other way which may be more convenient is to build a box to hold the battery and add to it a power distribution board with two or three auto cigar sockets ... wire these permanently to the battery using HEAVY GAUGE cable and check the polarity before use.

The difference between a deep cycle battery and a jump starter battery is that the deep cycle battery has a different plate construction - it is designed to deliver a small current (a few amps) for a long time and will survive being deeply discharged many times , whereas a jump starter battery is designed to deliver a huge current (over 100 amps) for a few seconds whilst turning an automobile motor starter unit but never expects to be discharged below 50% of its capacity and will be damaged if this occur; the damage is cumulative and will eventually result in the battery being unable to hold a charge.

Some people use electric wheelchair / golf cart batteries to power their scopes: these are usually rejected after about a year's use but are still plenty good enough for powering scopes. This is a good source of cheap medium capacity deep cycle batteries. New ones are much more expensive.


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Midnight Dan
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Re: Power Source question. new [Re: brianb11213]
      #5377083 - 08/20/12 07:19 AM

Hi Teabagger & welcome to the forum!

A deep cycle marine battery will work fine. But since they are large and heavy, you might prefer something more portable. The 5SE requires very little power and will go for many hours with a smaller battery.

A 7 amp hour unit like the Celestron Powertank will run the scope for a couple of long nights before needing recharging. As others have mentioned, you can get a 12V automotive jump starter for much less than a power tank and they can often be found on sale at places like Pep Boys or Walmart.

Another option is to use a small 10-cell NiMH rechargeable battery pack that attaches to the base with velcro. This has the added advantage of eliminating cord wrap issues. Note that using NiMH AA batteries in the internal compartment is not recommended. You can only use 8 cells that way and you won't get the voltage you need to run it for very long. This battery pack provides 4-5 hours of run time when I'm powering my 8SE and two dew heaters:



-Dan


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Bob Griffiths
Getting Grouchy
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Reged: 10/10/05

Loc: Frederick Maryland
Re: Power Source question. new [Re: Midnight Dan]
      #5377114 - 08/20/12 08:26 AM

You may be able to pick up a used Mobility Scooter 35Ah battery for free as many handicapped individuals replace their batteries in their wheelchairs/Scooters yearly as cheap insurance against being stranded.. I picked up a few from a wheelchair dealer who supplies nursing home residents for free because he has to pay to have them disposed of

What I Like about them is that they are not big, no more so then a motorcycle battery, are generally seal and have a built in carrying handle.. The best part is that they are designed to be fully discharged then fully recharged every day yet last for years...

The one I use in my observatory was used in a wheelchair for a little over a year BUT now, 7 plus years later it still works fine...BUT it now only holds 32 AH ...I keep it on a battery tender 24/7 when not in use...

New they run about $75.00

Bob G


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Teabagger
member


Reged: 08/18/12

Re: Power Source question. new [Re: Bob Griffiths]
      #5377854 - 08/20/12 03:53 PM

Thank you for all the replies. I have a 7ah little bat pack im going to use tonight(god willing).. I was also thinking i might try a 3 cell 18650 Lion BatPack.. that would be 12.6 fully charged close to 3ah. small and easy to charge.

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Tel
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Reged: 03/31/06

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Re: Power Source question. new [Re: Teabagger]
      #5378140 - 08/20/12 06:31 PM

Hi Teabagger,

Fine, by all means give these ca. 12V DC power sources a try but be very aware that whatever you choose to power your 'scope, connection to the mount socket MUST be tip POSITIVE. Any reversal of polarity is likely to fry the eletronics.

There are no fuses or diodes to prevent such potential damage from occuring.

Best regards,
Tel


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Midnight Dan
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Re: Power Source question. new [Re: Tel]
      #5378165 - 08/20/12 06:50 PM

Hi Teabagger:

You may want to check the voltage on that LiOn battery pack with a meter. Typical cell voltage for LiOn is 3.6 volts so 3 of them only provide 10.8 volts fully charged. I suspect it won't be enough to properly power the scope.

-Dan


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stryder
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Reged: 06/24/12

Loc: Cincinnati, OH
Re: Power Source question. new [Re: Midnight Dan]
      #5592726 - 12/28/12 01:49 PM

Sorry to post so long after the last one, but I'm getting a Celestron 8SE on Monday (Yay) so I've been reading about powering it.

I have a Sears portable jumper thing right now, but the thought of building my own is cool as well.

I emailed my local medical supply store to see what they do with their mobility scooter batteries, I'll keep you all updated.


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Midnight Dan
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Re: Power Source question. new [Re: stryder]
      #5593143 - 12/28/12 06:57 PM

Hi Stryder:

Looking forward to hearing about your battery project. There are others here (Bob I think?) who also use used scooter batteries.

You probably should start a new post when you do your update. Be sure and include some pictures!

-Dan


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cpl43uk
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Reged: 02/09/08

Loc: Bristol, UK
Re: Power Source question. new [Re: Midnight Dan]
      #5593798 - 12/29/12 04:51 AM

I have the 8se and spent a long time playing about with power options, especially with dew heaters etc. I tried the various cheap jump starters from places like Maplins in UK but have usually been disappointed. The celestron 7 and 17 ah systems seem to me to be more reliable but you certainly pay for the name and a bunch of gadgets you don't need. I therefore opted for a compromise.. A golf cart battery at 20 ah with 2 cigar lighter attachments. This is small enough to be portable (has a nice carry bag ;-) ) and can be kept in a small thermos bag to keep warm when the weather is very cold. Possibly overkill for the 5se but i no longer even think about power problems when out in the field. I keep my 7 ah celestron for the headlight when clearing up!

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Bob Griffiths
Getting Grouchy
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Reged: 10/10/05

Loc: Frederick Maryland
Re: Power Source question. new [Re: cpl43uk]
      #5593953 - 12/29/12 09:03 AM

One quick note...I'M CHEAP... !

I can pick up used Mobility scooter wheelchair batteries for free as my observation buddy sells fixes and repairs these things PLUS he does the work for more then a few local nursing homes.. It seem that the nursing home residents tend to replace their batteries about once a year just so they will not be stranded on the way to the dinning hall ..

The one I am currently using in my observatory was used for over a year in a power chair and I have used it for the last 7 years to power my scope Plus in the winter my heated clothing..

It no longer fully charges up to 35 Ah...now it only charges up to 31 or 32 Ah... still plenty good enough ...I keep it on a Batter Plus battery extender 24/7 when not in use..

For FREE I always BUY... For Money I normally waste time LOL

Clear skies...

Bob G.


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jturie
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Reged: 11/19/12

Loc: Valley Forge, PA
Re: Power Source question. new [Re: Bob Griffiths]
      #5594079 - 12/29/12 10:22 AM

You might want to check this out for a DIY field battery setup:

http://myastroimages.com/Equipment/Telescope_Field_Battery_DIY/index.php


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stryder
member


Reged: 06/24/12

Loc: Cincinnati, OH
Re: Power Source question. new [Re: jturie]
      #5597108 - 12/30/12 11:08 PM

I ended up getting a replacement battery at Batteries Plus locally in Cincinnati. It's only 12ah, but it should work for now while I get more gear. Once I get a dew strap and all that I'll move up to the marine batteries.

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Midnight Dan
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Re: Power Source question. new [Re: stryder]
      #5597580 - 12/31/12 09:27 AM

That should do the trick!

-Dan


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