Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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I have an Orion SkyView Pro mount and I'm in the process of coming up with a new battery solution for my Orion TrueTrack drive. So while I'm researching I thought I'd ask here for any ideas members might have come up with.
The problem I'm trying to solve is two-fold. First, the drive is designed to use expensive and heavy D-size primary cells. I would like to create a rechargeable solution. Second, Orion told me, in an email, that there's no voltage regulation. This jives with a comment I read saying that the drive slows down when the battery voltage drops. So I'd like to create a rechargeable, regulated solution that's cheap to operate and keeps the drive speed consistent. Of course, it can't be so expensive that it takes 20 years to come out ahead!
Here are a few solutions I'm considering...
1. 6V 2300mAh NiMH pack.
Cost is $7.99. It's unregulated, but I think NiMH voltage is more reliable than primary cells. I already have a charger I can use, so for the price of a Duracell D-size 4-pack I can have a rechargeable solution. I also like the idea of just Velcro-ing the pack to the back of the controller and getting rid of the separate battery pack.
2. 11.1v 2300mAh Li-Ion battery + tiny 1A dc-dc step down regulator.
Pack is $29 and regulator $15. Can probably Velcro both to the back of the controller. I'll need a charger, which is another $25. This will probably work the best, but $70 buys a lot of D cells!
3. AC-DC Switching PS 1A regulated + inverter + 12V power source.
$16.95 for the regulator, $20 for cheap inverter (don’t know if it would work.)
This is the “size doesn’t matter” route. I already have one of those booster batteries for my car, and I even have a sine wave inverter, so all I really need in the power supply. But man is this a bulky solution! The battery, at least, has it’s own handle but there’ll be more stuff to carry and setup, and wires everywhere.
EDIT:
4. I found a 2A regulated 12V/24V to 1.5V-12V adapter. That's 15 dollars. Not as bulky as solution #3 but still need to use the big battery.
So those are my ideas so far. Thoughts?
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Warning! I'm a newbie...I don't know anything!
Edited by Graystar (05/16/09 01:12 PM)
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Luigi
Post Laureate
Reged: 07/03/07
Posts: 4888
Loc: Massachusetts
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Believe it or not, D size alkyline batteries have a capacity of about 20 Ah at low discharge rates. That's almost 10x what you're planning for your rechargeables. Probably the best bet is to look up a battery store in your neighborhood and get a 6V gel cell with 14 An or greater capacity. It'll be heavier than the D cells though. Another option is getting a DC-DC converter to take a more standard 12V down to 6.
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Discovery 17.5" f/5. IM 7" f/15 MCT. Eon-120ED
Lunt 60mm Ha on Nexstar mount.
CG5ASGT, Orion Skyview AZ
9 Nag. 35&19,Pans. 24.5 4kSWA. 14&4.7 5kUWA Meades
6, 9, 12.5 UO-AO. 3mm Edge-on. 7mm BO-TMB
Zeiss, Leupold, Bushnell spotters
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One each generic rescue Greyhound
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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I found two solutions.
The first is a 12V powered selectable voltage converter. It was 16 bucks and included a 120AC-12DC converter for home use. Here are a couple of pics...
I bought it at batteryspace.com, but I saw a similar one at my local Rite-Aid, so I'd say they're available just about anywhere. This was the only, however, that I saw come with a 120AC adapter.
The 6V voltage is 6.14, which should be good enough for accurate operation. I power it with my Jump-N-Carry jump-start/power supply unit. Weather report says I won't see stars for a full week from today so that's when I'll check how well it tracks.
Not content to leave well enough alone, I also purchased a NiMH battery and tiny voltage regulator that I intend to double-stick tape to the back of the drive controller. That would make one less wire to trip over. I'll let you guys know how it goes. Here's a pic of the parts...
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Warning! I'm a newbie...I don't know anything!
Edited by Graystar (05/26/09 10:06 PM)
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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Here's my "proof of concept" assembly. I was a little worried about the added bulk and weight, but to me at least, the controller feels a little nicer to hold because of the weight. The voltage regulator seems really good, registering 6.01 volts. And so far it seems to drive the motors with no problems. But then again, the regulator is rated for 5 amps and I already measured the draw of the two motors at less than 1 amp...so I didn't expect any problems.
So now I'm just toying around with ideas on which way to run the wires, should I get an "L" connector, etc. I'm also considering just wrapping what's there in black duck tape and calling it a day :P
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Warning! I'm a newbie...I don't know anything!
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E_Look
Pooh-Bah
Reged: 03/06/08
Posts: 1204
Loc: near New York
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Ingenious and fascinating!
I have only a single axis drive (RA) on my SkyView Pro. I too am thinking of some way around the necessity of using FOUR D cells.
But I wonder, isn't there maybe a (Radio Shack or some other outfit's) "wall wart" type plug-in tranformer that could supply an acceptably constant voltage at 6 VDC?
My only problem with that is that I'd need one of those hefty orange outdoor extension cords to connect it to some house current...
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Ed
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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Quote:
But I wonder, isn't there maybe a (Radio Shack or some other outfit's) "wall wart" type plug-in tranformer that could supply an acceptably constant voltage at 6 VDC?
My only problem with that is that I'd need one of those hefty orange outdoor extension cords to connect it to some house current...
That's what the first two pictures are, with the additional advantage of being able to use it with one of those commonly available 12v battery power supplies. So when you're home you'd plug the wall wart into the extension cord. That supplies 12 volts. Then plug the 12v auto connector into the wall wart adapter. Away from home, you'd plug the 12v auto connector into a portable 12v battery power supply. If you have one of those portable jump-starters for your car, then you're probably all set.
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Warning! I'm a newbie...I don't know anything!
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Fortune07
super member
Reged: 06/17/08
Posts: 108
Loc: Adirondack Mountains, Upstate ...
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The only thing to remember when using any of these solutions is that it must be connected, center pin positive. The Radio Shack converter that I used with my SVP came with a tip that could be reversed.
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Jeff
Orion XT10 Classic
Orion SkyView 8" Newt
Orion 4.5" imaging Newt
Atlas EQ w\EQMOD
Phillips web-cam
Atik 16IC mono
Atik 16IC-S
Dell 1530 Laptop
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Wildthing
super member
Reged: 11/07/07
Posts: 186
Loc: Muncie, IN
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If your looking for a 6V DC REGULATED wall supply / cube supply, then go to Horizon Hobby and check out the EFLC1005 6V 1.5 amp AC/DC Power Supply. It powers my Celestron Omni CG4 GEM mount that I added the 2 Celestron motor drives too. Here is the link to the 6V DC supply.
http://search.horizonhobby.com/index.jsp?N=0&Ntt=eflc1005&sid=122002E14063
Clear Skies, Donnie
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Clear Skies, Donnie / Muncie, IN
Equipment:
Stellarvue SV-102ED f/6.95
Celestron CPC 800 XLT
Orion 100mm f/6 Achro
Mounts:
TV Gibraltar w/Sky Tour
Celestron CG5-GT Mount
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E_Look
Pooh-Bah
Reged: 03/06/08
Posts: 1204
Loc: near New York
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How's your regulated battery and charger working?
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Ed
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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Are you asking me or Wildthing?
If you're asking me, I haven't had a chance to really use the battery/regulator combo because of the unbelievably bad weather we've been having in NYC. At home, I’ve been using the combo of the 12v auto adapter and 120AC-to-12v-auto adapter to power the drive whenever the clouds have some holes in them. I thought last night was going to be good but the clouds were out.
The 6V auto adapter seems to keep Jupiter in the eyepiece, and I’d expect the battery to work better because the regulation is better.
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Warning! I'm a newbie...I don't know anything!
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gnowellsct
professor emeritus
Reged: 06/24/09
Posts: 617
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Well get yerself an 80 amp hour marine battery (or less) and a charger and an insulated beer case from Walmart. Couple of alligator clips. Put in a five or ten amp in-line fuse for good measure. That will take care of your power problems and you'll have power when it's cold too.
I've been using this system for ten years. Threw my D cell battery packs out. Greg N
Edited by gnowellsct (06/30/09 11:25 PM)
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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Quote:
Well get yerself an 80 amp hour marine battery (or less) and a charger and an insulated beer case from Walmart. Couple of alligator clips. Put in a five or ten amp in-line fuse for good measure. That will take care of your power problems and you'll have power when it's cold too.
My issue wasn't simply power...that was figured out easy enough with an auto adapter with adjustable voltage and my 9 AHr jump-starter/power supply battery. The real issue was how to provide a perfect 6 volts to my controller, so that the drive runs as accurately as possible. This was a concern because I had read that my particular drive will run at different speeds based on the voltage.
My battery/voltage regulator solution pictured above provides up to 5 amp at a measured 6.01 volts. That's pretty good.
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Warning! I'm a newbie...I don't know anything!
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E_Look
Pooh-Bah
Reged: 03/06/08
Posts: 1204
Loc: near New York
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I was asking you, Graystar.
Thanks for the reply. I have an Orion SkyView Pro EQ mount on which I installed a motor drive on the RA axis. I don't notice any RA drift... yet, for my motor and four D cells are new still...
... so I was just wondering how you made out. Maybe in several weeks, you can more report back to CN in more depth!
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Ed
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John J
super member
Reged: 11/05/07
Posts: 177
Loc: Sioux Falls SD
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I kept my battery pack as the motors are steppers and not really controlled by voltage but frequency. I did want to get rid of the extra cable though. I shortened the battery pack cable and Velcro'ed the controller to the pack. It is nice to have the strap to hang on the mounts altitude adjustment knob. The white cable is an ST4 guide port. These D batteries have lasted at least 6 months so far and that is with autoguiding.
http://s544.photobucket.com/albums/hh349/johnj449/?action=view¤t=DSCF0484.jpg
http://i544.photobucket.com/albums/hh349/johnj449/DSCF0485.jpg
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Things are looking up!
http://inskysd.org/gallery/
My Flicker Astro Site
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kenfoland
journeyman
Reged: 03/27/09
Posts: 8
Loc: Good 'Ol USA
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Before I got my Atlas EQG I had a SkyView Pro 8EQ which I liked a lot, in the beginning. But, anyway... I powered the mount with two 6 volt 4.5AH sealed lead-acid batteries, the type used in alarm system power packs. I wired them parallel when in use with the mount and series when charging with a small 1.5-Amp 12-Volt automotive trickle-charger. These chargers are great for maintaining lead-acid batteries while in storage. Unfortunately, the SLA batteries are pretty heavy. But, with the mount drawing say .5-Amp average power they would supply the mount for over 18 hours with no fluctuation. The SVPs RA drive unfortunately does suffer speed inaccuracies from voltage fluctuations. This quality is a deficit for astrophotography. Ultimately, this is the reason I abandoned the SVP for the Atlas. I power the Atlas with a power pack from my daughter's Mongoose 24-Volt electric scooter; two 12-Volt 10AH SLAs. This pack will power the Atlas all night, or at least as long as I can last. And, is easily charged/maintained. The Atlas has much better electronics than the SVP and does not suffer the fluctuation problems the SVP does.
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Equipment:
Orion Atlas EQ-G W/ BluEQ Bluetooth Interface
Orion 8" Newt W/ Low Profile Crayford Focuser
Coronado PST
Canon 300d Modified for Astrophotography
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"Me no dum-dum. You dum-dum." - Moai from Night At The Museum
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John J
super member
Reged: 11/05/07
Posts: 177
Loc: Sioux Falls SD
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I think many people are mistaking the SVP fluctuations as a controller or voltage problem. The controller uses a microprocessor that simply sends timed pluses to the stepper motors. Most of the problems with with the SVP is the error in the worm and gears periodic error. The stepper motors are also plagued with backlash problems. All these things combined may make it seem like there are voltage fluctuations.
It certainly doesn't hurt to regulate the voltage to the controller but once battery voltage drops so far there will not be enough current for the motor to step and hold like steppers are supposed to. Just not enough current to produce the torque required.
JJ
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Things are looking up!
http://inskysd.org/gallery/
My Flicker Astro Site
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Graystar
member
Reged: 04/19/09
Posts: 84
Loc: Brooklyn, NY
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I decided to test all this out by recording the time required for one revolution of the motor with no load. With the auto-adapter (shown above) set to 5V I recorded a time of 9:57.68, and with the 6V regulated battery I recorded 9:57.22. And that was just by eyeballing the position of the gear. I can perform a more precise test but I don't think it's necessary. I think it's clear that the voltage does NOT affect the speed of the motor.
So super-precise voltage regulation isn't necessary for good tracking. Still, there were other reasons to do this...avoiding the purchase of expensive D-size batteries, and to get rid of the separate battery pack. So for anyone who wants to lose the battery pack I'd recommend a 5-cell AA NiMH battery pack and just duck-tape it to the back of the controller.
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Warning! I'm a newbie...I don't know anything!
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E_Look
Pooh-Bah
Reged: 03/06/08
Posts: 1204
Loc: near New York
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LOL, John.
I truly wish there was a better way to keep that D-cell battery pack than just hanging that heavy box off the altitude bolt. I'm going to get some new Velcro with a better adhesive to hold the controller box to the tripod legs, as the strip that came with the motor/controller/battery pack kit had a pretty poor adhesive on the back. I hope to find a strip with a good adhesive so that I can maybe also hold the battery pack to the tripod legs, too.
If frequency is what regulates the stepper motors in these RA or DEC drives, then the solutions might be expensive. I'm no means all that knowledgable in electronics, but I've never heard of a cheap controlled frequency power supply.
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Ed
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