"Run Your GOTO Telescope all night long with our deluxe, heavy-output POWER- MAD SUPER DYNAMO rechargeable battery system! Only $39.95, complete with built-in radio, red/white lantern, tire inflator & motorized bottle opener!"

Sure, I've been tempted -- you've been tempted, too. The glossy-catalog picture shows a chrome-trimmed, sexy looking contraption that DOES seem to cry out, "I'm powerful!"

Far below the breathless prose describing the delights of the useless functions thrown in -- like lipstick on a pig, unrelated to any real need for a reliable long-lasting draught of juice for your scope and laptop, and maybe your deep-sky CCD imager -- is some tiny fine print that might admit, embarrassedly, "rated at 12 AH. Comes with 300mA 115VAC-to-12VDC charger." Or perhaps you have found a similar gadget in an auto parts or hardware catalog, advertising a "powerful jumpstarter system and emergency tire inflator."

Do these things WORK?

Certainly. If fully charged, your fancy new "power system" might run your laptop for, oh, 45 minutes. You might get an hours' use of your C-8 or C-11 GOTO scope. That is, if you don't slew to more than three or four objects...

When I owned motor-driven telescopes in the 1980s-90s (an old orange C-8 with the early pair of 110V drive motors, and a big old Newtonian with one single 110V hysteresis-synchronous clock motor on the right ascension axis), I could power the scopes right from the wall outlet at home, or run them in the field using a simple, gutless drive corrector that was no more complicated than a TTL chip and pair of TO-3 output transistors in a multivibrator circuit, drawing a few tens of milliamps. A 6V lantern battery or some D cells would run these contraptions for about two nights' use. The motors in the Celestron scope drew no more current than the one in my little old 1945 Telechron electric kitchen clock. Sure: they needed 110VAC; but drew only a watt or two of power.

When I shopped for a GOTO scope in early 2005, I had no idea what to expect in terms of power consumption or battery life. Of course, I searched for information on the Net. There are umpteen reviews and articles that touch on the subject, peripherally, but little in-depth discussion. The salesman at the telescope store was a bit evasive, but essentially "told me what I wanted to hear": that THEIR little power tank would work "ok". It was rated at 12AH. I had three of them at home, very similar Chinese made devices for jumpstarting and tire inflating; those surely would be fine. We agreed on that...

Cheaply made but fancy-lookin' Chinese gel-cell jumpstarters/tire inflators, with 12 AH batteries. I stole the alligator clips off two of these for my battery charger. These were nearly a total waste of money; I only use them now as flashlights, to be sure I haven't left anything on the ground at my mountain top observing site!

I decided that, to be prudent, I'd use TWO for astronomy, one for the C-11 scope, and one for the laptop. And on "first light", during a star party at Montebello Ridge on the occasion of the collision and explosion at Comet 9P/Tempel 1 on July 4, 2005, I had the systems powered up and trained on the comet just long enough to start seeing significant effects, when -- BEEP! The laptop power inverter's built-in low voltage alarm shrilled out a screech at 110 decibels, causing an eruption of complaints and cat-calls from the nearby observers. "Quick, Alt-F4!" I hissed at my friend Charlie, sitting at the laptop. "Close it down NOW!" He shut off the computer. I pulled the plug to the now-exhausted "power tank", more like a "power sippy-cup" in reality. About ten minutes later, the C-11 just went dead. The hand-controller illuminator stayed lit but the LCD went blank; the buttons did nothing; the scope stopped tracking. Zippo, nada: the thing was out of juice and stopped without a whimper or warning.

Two independent 12AH batteries had not given me a full hours' use, under the stars in real-world operating conditions.

Later, I opened up the Chinese jumpstarters, and was horrified to discover that the connecting leads were surely no more than flimsy no. 18 stranded wire. I replaced them with doubled-up parallel lengths of no. 10 wiring, and shortened the lead distance to the big output connector; and recharged the batteries fully again. I got about the same result on the C-11 scope: no more than 50 to 60 minutes' operating time. I tried discharging and recharging the gel cell batteries according to appropriate instructions, cycling them several times to make sure of a REALLY solid, strong full charge. Ditto: the same result. Then I got ahold of one of the "official" telescope battery systems made by a certain company, sold specifically for their GOTO instruments. Inside was the same brand of Chinese battery as the jumpstarter I found unsatisfactory. Simply put, the 12 amp-hour rating was INSUFFICIENT. If the battery voltage dropped to a tiny fraction of a volt below 12VDC, the C-11 simply stopped operating. I tried running the battery into a 150-watt inverter, and then operating the scope using its 115 VAC transformer adaptor. This actually resulted in a little longer operating time, yielding perhaps a 25% (or greater) improvement depending on the battery used (since the inverter held up its output voltage longer, perhaps having some regulation effect.) But, 65 to 90 minutes' use is not much more satisfying than 50 minutes...

"Perhaps these batteries are simply defective: they can't hold a good, solid charge," I pondered. So, I picked a 17AH Husky brand jumpstarter, in the $40 price range, which certainly did give longer performance. Later I found even higher capacity "name brand" Vector supplies: units that are rated at 19AH, weighing more than twice as much as the cheap Chinese systems -- and I believe it! They are hard to lift. The big connecting leads and alligator clips look like they mean business. I could probably use one to start a frozen Humvee at McMurdo Station. In fact, I was lucky enough to obtain the Vectors on sale at Big Lots for only $24.95 each.

Better quality, heavier duty jumpstarters, with 19AH batteries (yellow Vector models) and 17AH battery (red Husky). They STILL would not run my equipment for the time duration I required. BUT THEY WILL START MY CARS!

The results? From a full charge (all four LEDS lit, including the "green" one indicating tip-top charge status), I can operate the C-11 for about -- deep breath, now -- only a bit longer than TWO hours, with the 17 AH Husky battery connected directly to the scope's 12 V input (somewhat longer via the AC inverter.) My laptop will run for three hours, via an AC inverter, from the 19 AH battery.

[Sound effects: gnashing of teeth, grumbling, growling.] All right! I'm through messing around! TIME FOR THE BIG STUFF!

"What's so complicated?" you might ask. "All you need to know is the current consumption of your telescope, right?" Well, that's part of what you must know. The C-11 manual has very little information: a broad general spec covering all three of their GPS models (8" to 11": is there no difference in load?) and the vague statement that the power requirements are "12VDC, 1.5A (Tip Positive)" which was contradicted by various advertisements I found on the Net that stated "1A". The manual claims a range of acceptable input voltage for all the GPS models: from 15V down to 9V. But, MY telescope "dies" if the voltage drops only slightly below 12V, if driven directly by a battery and not the AC to DC power supply. A hint of what Celestron believes is the appropriate portable power supply is afforded by the specs for their own "power tank": they sell two models, rated at 12AH and 17AH. That is the exact capacity of the ones I have tried unsuccessfully. Celestron makes no claims whatsoever about the charge-longevity of either unit when used in the field with any particular model of scope...

What one really needs to know is a lot more specific information, about both telescope AND battery system: such as --

• Peak power load and duration under slewing, versus steady load while tracking;
• Exact input voltage regulation range for each model aperture size during all hand controller operations;
• Battery output current sinking factor, versus voltage, under supported load;
• Battery output voltage stability plotted by load, and over time.

What I had experienced in the field showed that the cheap rechargeable "tanks" or jumpstarters MIGHT run the telescope long enough to set it up and start observing...but not for a normal viewing session. Had the manufacturer ever sent them into the field, with amateur astronomers, for REAL TESTS? I doubt it. Probably, an engineering manager had just looked at some rudimentary specifications for the electronics; looked at the same for a battery; and concluded that for some average amount of time for a 'typical' observing session: "that'll work." But, was a determination ever made for long observing sessions with lots of slewing, in cold environments or with a wide variety of battery brands?

And I had the same experience of the salesman "telling me what I wanted to hear" when I bought the laptop PC to use with my telescope. When I asked about the battery life (since it was not mentioned in the advertisement or the manual), telling him I needed to use the machine all night with my scope, he replied, "Oh, well: I am sure you will be able to get about, say, um, err, at least four or more hours!" Turns out, however, that the internal battery, when fully charged (external status LED colored green for go), will run my little Acer Aspire 3500 for about a half hour. I can push it further, if I set it up to go to sleep after 5 minutes; but then it is useless and frustrating when running back and forth from laptop to scope, to find objects with a star chart program, or to send slewing data to the scope. For the latter function, it must be running all the time, and not constantly logging me out of Windows and turning itself off.

I needed to know the "worst case conditions" for the most demanding use of both scope and laptop.

Time for some serious Internet research; must have taken me a week. First I tried to get some specific questions in my mind answered via the Google archive of sci.astro.amateur. You might as well beat your head against the wall, for the various threads I turned up all suffered from the usual topic-creep and superficiality that is now standard in usenet. The best one I found was this thread, about Gel-cell vs. Lead Acid batteries; I'll admit gratefully that several of the respondents were quite well informed. But, at first the idea of lugging around a horrible car battery repelled me. And I remembered that several times in decades past, I'd discovered that I had left a car dome light on over a weekend, or perhaps had accidentally left a sedan front door open in the garage. I came out Monday morning and found that I had a dead battery. Imagine that: you have a big old Die Hard under the hood, something monstrous and smelly that can sink 600 Amps into a starter motor...and a 2 watt dome light discharges it completely in less than 36 hours!

I knew that there must be a better choice than a dangerous, fume-producing lead acid battery. To simplify the story, here are some of the links that I ran down when trying to learn the answers:

• Camping Power Management Tips by George Schreyer;
• Deep Cycle Battery FAQ, an extraordinarily useful, informative, and comprehensive webpage, by Northern Arizona Wind & Sun, Inc., with a list of helpful links at the end;
• CAR AND DEEP CYCLE BATTERY FAQ, compiled by Bill Darden: a plethora of links to informative articles;
• Field Power, a page by a guy after my own heart, who pictures all his battery chargers, jumpstarters, and power supplies for astronomy. He has a LOT of them!

I came away from this with some conviction that I wanted to get an "AGM" (Absorbed Glass Mat) battery that was sealed, consequently being safer to transport than a conventional lead-acid car battery, and vents scarcely any dangerous and flammable hydrogen fumes due to the positive- pressure sealed vent valve. These batteries DO contain sulfuric acid, and are very heavy...but they are made in high capacity units that in the "Marine" category are a good compromise in service between the "starting" type (extremely high current for a short period of time), and the "Deep cycle" battery (long- usage steady current discharge all the way down to about 20% remaining output.)

I made phone calls to local San Jose and SF peninsula "marine" and recreational vehicle dealers, and discovered to my dismay that NO ONE has manufactured a "ready made" battery system that would truly satisfy my needs: a turn-key unit that had everything in one package, at an affordable price. I did locate a very costly -- but ultimately underpowered -- system, made by Xantrex: the XPower Powerpack 1500, which a local computer dealer had on the shelf, but at a price well above $300. But, unfortunately, the chart of performance given in the manual tended to indicate that the internal 60 AH 12V battery would not supply enough power for more than one night's use of my telescope and computer. It would only run a small 13" TV set for four hours, and a fax machine, or tire inflator, for only three. That's a LOT of money for a short duration of portable power.

At this point, I shall digress and explain WHY I think that ordinary folks are not truly conditioned by day-to-day experience to understand, really, just HOW MUCH POWER they consume from their 110V home outlets.

Every one of them is designed, by law, to supply no more than 1500 watts of AC power. But that 1500 watts may heat up an entire large room in a few minutes; run enough lights to practically blind you; operate an oven to cook a big meal for a large family; run heavy power tools; send enough juice to a power-gobbling giant-screen plasma TV to make a pauper of you when the power bill comes due.

We don't THINK about it. We just plug in something; turn it on; and let it rip. We're all used to paying $200 a month -- maybe $400 if you live in the hot southwest! -- for electric utilities. That two hundred dollars buys a LOT of kilowatts.

But, commercial power users get bills that would make your head spin. I remember years ago that one of the radio stations I engineered got a THIRTY THOUSAND DOLLAR A MONTH electric bill! Never mind what a factory has to pay...

That Celestron C-11 telescope of mine draws so little current that I could plug it in to my wall outlet and forget it...perhaps the bill at the end of the month would be a couple dollars more; I wouldn't notice it. But, to supply that same current AS TWELVE VOLTS, DC, from a battery is not a trivial matter! I would have to line up a couple dozen big, hefty AGM batteries -- each costing about two hundred bucks -- and switch over to them every 36 hours or so. If I had no chance for recharging them but still had to have continuous power, I'd have to pony up $4800 to keep that scope alive for a month.

Luckily, I have no need to run my GOTO scope for more than three days from battery power. I might just eke out that much time from one 92AH battery; at least I'd get almost three full nights of use. I could always recharge it with a solar panel during the day, or from my car battery system.

I reckoned that I'd have to spent at least $200 for one battery, preferably $400 for two, so that I'd have juice to run the LCD portable TV in my wife's "Little Guy" travel trailer. And I'd need a charger; but not a cheapy. AGM batteries require a special charger, operated by a microprocessor- controlled regulator and timer system. The input charging voltage is CRITICAL. It must be kept in a narrow range; when the charge current drops to a threshold, the system switches to a safe "float" mode. While I did find some inexpensive chargers that claim to offer such a feature, I decided that I was not comfortable with trusting a $200 battery to a $39 charger. So I got a professional charger system that set me back more than $150.

I was still working by the seat of my pants, since nowhere on the Net had I found an article by an amateur astronomer that illustrated EXACTLY what was necessary to make a big GOTO scope and laptop work in the field for at least two days. So, I opted for overkill, since I had already wasted so much money and time on the "conventional wisdom" that I could get away with portable jumpstarters.

Nicely overexposed flash snapshot of our 10-inch Axion LCD television in the "Little Guy" trailer, sitting on top of a 12VDC VHS video player. For audio, we run a 40 watt Radio Shack car equalizer/amplifier, into two 5" speakers. We also use a small portable DVD player with the same system, and Regina can enjoy videos when she poops out on astronomical viewing long about 11 pm, while Stephen keeps going strong, looking for faint PK nebulae 'til all hours. The "overkill" battery system described below runs all this gear very reliably.

Here's what I got:

• Xantrex TrueCharge10TB 10-amp multi-stage dual battery charger/regulator;
• West Marine SeaVolt 12V AGM, Group 27, 92Ah battery, West Marine model number 1231406.

With tax, and even a small discount offered for buying two batteries, the cost was approximately $600. (If I had known I'd have to do this, before I bought the telescope and laptop, it might have killed the whole deal.)

But, all I had now were two big, heavy (65 lb. each!) batteries and a charger, sitting under my garage workbench. I'd need to wire them up to something portable. So, I purchased two battery boxes, and some cables and splitters. The battery boxes were pretty expensive, considering their simplicity: I had chosen the Tempo PowerCenter model, which is all wired up and ready to go, with fusing and an LED voltage indicator. But, I had to add a second 12V fused output terminal to each one, costing another $15 or so. By the time I added up the various leads and battery power splitters, I was out at least another $90 for the battery boxes and accessories.

This stuff REALLY works! Above, the two West Marine SeaVolt 92AH AGM batteries, in Tempo fused cases, connected to the Xantrex TrueCharge 10B dual charger/regulator.

As I said, overkill. But IT WORKS. The batteries are state-of-the-art and nearly highest possible quality, albeit short of mil-spec. They don't run down in the field; I have yet to make a DENT in them during a vacation trip. I expect that they will last me at least a decade; maybe longer, since I am careful about their temperature, charging, and discharging rates.

If I go observing for one night, using both GOTO scope and laptop, I take one battery. For more than one night, or for sharing also power with my wife's appliances and devices in her travel trailer, I take both of them.

BUT...this does not factor in the -- dreaded -- DEW HEATER!

My Orion #03512 Dew Zapper™ for 11" Schmidt-Cassegrain telescope draws 2 amps! It will deplete one of my Chinese jumpstarters in less than twenty minutes. I suppose that one of my big AGM batteries would be sufficient to power it for a night, but what a waste! So, I simply gave up trying to use it in the field. Instead, I built a home-made dew shield for the scope, which I bolt on to the tube assembly side brackets (it was necessary to make my own rugged and foolproof unit, since I sometimes observe in a mountain-top area where winds might gust up to 20 mph for a few seconds; an ordinary commercial dew shield would be flying down the dirt road or over the side of the hill before I could move a muscle to retrieve it!)

Rampant on a field of Delosperma cooperi, repose my home-made C-11 dew shield covers, which bolt firmly onto the side brackets and then latch together at the front with Velcro™. No blustery gust can disturb THESE. Before they would come off, the C-11 would be knocked over onto the ground!

Finally, I should repeat that I operate the Celestron C-11 not directly on the 12V battery line -- that requires a BIG, low-loss power cord! -- but from a small 150 watt DC-to-AC inverter. I have several of them, and you can find anything suitable at a department store near almost anybody. The only caveat is that the instructions for my little Fellowes 150W inverter say that you should not plug in a load with the unit turned ON. Plug in the load, and turn the inverter power switch on to avoid an overload. I also picked up a heftier Vector VECO34 225 watt inverter for running my electric razor (I wouldn't be caught dead observing with stubble, now, would I! Who wants to observe with that grungy "Richard Nixon" look?)

A panoply of inverters, adaptors, power transient suppressor, and 12V blower. With this, I can watch a movie, run my radio, CD player, electric razor, laptop, C-11; shave; dry my hair -- or my corrector plate: all at the same time, from two 92AH batteries that have NEVER, ever, run down during away-from-home excursions.

The cost was staggering -- I'd hate to add the whole thing up, mistakes and all -- but I finally got what I wanted, and needed. Be warned that if you have very specific requirements for long-term portable power, you get what you pay for.

Post Script: Well, wouldn't you know it? A few months after I spent over $600 on the SeaVolt/Xantrex power system, I found a gigantic palette full of nearly-new 90 AH AGM-type batteries at one of my favorite bay area electronic surplus stores, Weird Stuff: they must have had at least 200 of the darned things. And the price? A mere $25 each! I had paid $400 for a pair of brand-new 92 AH batteries; grumble! My friend Charlie purchased one, at my suggestion; he told me that it worked fine, as soon as he managed to wait long enough to give it a full charge with the cheapie $35 float charger that we found for him at Boater's World. Weird Stuff's website does NOT list the batteries, so perhaps they won't ship them anywhere, or -- by now, a few months later as of the time we wrote this article in June, 2006 -- they have sold them all. If you are curious, you might call them at 1-408-743-5650 (extension 324) or fill out their website query form. I'm merely a happy customer of Weird Stuff, but I like them so much I put up my own "tribute" page. (And, recently -- in September 2007 -- I saw in their large back room that Weird Stuff still has a considerable number of such batteries.)

Update, 3/26/07: A reader of this article managed to route an email to me, about battery life, which I'll quote in part.

I'm an active amateur astronomer/physicist, and do some of the same kinds of things you do. I can't believe I had not seen your materials before tonight, but find them interesting and even informative! ...

Just a couple of remarks on some of what you've written.

Re battery life and goto scopes. Perhaps the reason your battery life that is far less than what you should get is that the manufacturers are using old, out of date batteries. The gel cells and their variants definitely have a finite (4 year or so) life, used or unused. I have worked with new ones in the 7-12 AH range, and find that they in fact deliver exactly what the nameplate says, time after time. I have recently gotten a CPC800 C11 scope (which I actually like quite a lot) for portable use, and have powered it for some 8-10 hours with no signs of a problem (this is using 12v 7 AH battery directly).

My reply to him:

This might be true but [a dealer selling that brand of scope] said that the brand new batteries THEY sell in the store are not able to run the Celestron GOTO scopes for more than about 2-3 hours and are always pooped by the time they end one of their occasional observing nights, demonstrating the scopes.

Since the last time I updated my article I discovered that the 17 AH Husky gel-cell system that gave me about 4 hours with the scope has now, a year later, degraded to the point where it will not achieve a full charge; cycling it did not help and it gives about half the duration of output that it produced when I first tried to use it with the telescope. Apparently the battery was damaged by running it four hours until the scope just would not work any more.

So I am not able to get one that will work for a whole night and after testing about 6 different ones, have not had the results you were able to get, [nor those which some others have claimed for their not very thoroughly explained situations.]

Furthermore, I am not even sure that the battery DRAIN is the determination of the running time, as I did a test recently with only my laptop, running from a small inverter. It does not even draw an amp. The gel-cell system, rated at 18 AH, ran the PC for about 2-1/2 hours before the inverter's warning beeper started sounding, the voltage having dropped to about 11.75 VDC. I had to change batteries at that point.

This convinced me that no matter what I do, the only way to run my equipment is on the big marine battery, which weighs 65 pounds and is rated at 92 AH. I use it for the laptop and scope, and at the end of perhaps 8 to 10 hours of use, the battery is sufficiently discharged that the top "full charge" LED is no longer lit when I press the test button on the battery case; sometimes even the next light below that will be off, too. I haven't had a voltmeter with me to check the voltage. But the battery is still good for another night, without a charge. -- srw

Addendum, Summer 2007:  I continue to use my AGM batteries quite successfully and have so far been able to operate my laptop and GOTO telescope for a total time, over three days, of about 20 hours. But, the LED charge display on the battery box shows that the charge is seriously depleted, so one does not know quite how much current is available, at the necessary voltage, under the required load. After two successive days of using both the scope and laptop, each connected via its own inverter to a separate 12V connector to ONE battery, for a total operating time of 16 hours, I noted that the LED display now showed a half-way indication. This is too coarse to be meaningful, so I used a digital voltmeter to check the voltage, unloaded. My unused, charged battery registered 13.5 VDC. The partially-depleted battery showed, however, only 12.2 volts (unloaded); this of course would drop significantly under full load. Since my tests earlier had shown that my scope system was on the verge of shut-down if the voltage into the power inverter was much below 12 VDC, there wasn't much "poop" left. One also has to worry about over-discharging any battery. "Marine" battery types -- also known as "deep discharge batteries" -- will indeed handle a heavy discharge better than conventional lead-acid or gel-cell types (which may be permanently damaged and weakened.)

I might have been able to eke out another (short) night of observing at this point, but the battery really needed to be "topped off" from the car, or my portable solar charger, before further use.

Now, when I first produced this article, as what I hoped would be an aid for a few other amateurs who might have similar needs -- written after I discovered that there wasn't much on the Net that was specifically related to complex needs for powering astro gear -- I thought my time had been well spent in the cause of furthering knowledge. But, when my wife notifed the newsgroup sci.astro.amateur of the article, the yahoos really came out of the closet to "negate" it. There is a significant group of what I'd call "know-it-all" types who PROJECT their own personal needs and experiences onto EVERYBODY ELSE IN THE UNIVERSE. If you, dear reader, happen to have a slightly different personal experience, then "you are wrong". These hand-wringers seem extraordinarily upset if somebody writes about their personal experiences. I wrote this article not to say to my readers "THIS is what you must do", but to say "Here is what I did, because I found it necessary."

One by one, the nattering nabobs of negation piled on to "inform" everybody else that this article is surely irrelevant. In no case did an objector actually seem to have MY equipment. Nor did they seem to have MY needs.

Some of the "corrective advice" given was actually dangerous. One misinformed and ignorant person suggested that all you need to do is get a "cord to plug into your car cigarette lighter, which is what I do." This of course is a tricky business and MIGHT likely cause you to discharge your car battery, leaving you stranded at a distant observing site (mine is on top of a mountain.) Deeply discharging a conventional lead-acid car battery overheats it, likely resulting in permanent weakness or ruination.

It should be emphasized that YOUR needs are not necessarily MY needs. I am NOT, in any of the posts I make or the articles I write, "instructing" others what to do, what THEY need, or what they must think. I would expect that other amateur astronomers might find my occasional experiences interesting, if only as "data points" about what happens to somebody else. But, sadly: no. It seems as though there is a large insistence by a certain mindset of amateurs that there is only one narrow "right" way of doing things -- THEIR personal way. I have no objection at all to knowing what THEY do; in fact, this article resulted by my attempting to DO WHAT OTHERS SAID THEY DID, and finding the results unsatisfactory. I needed something better, something different -- and that's what I came up with. You might not need to know ANYTHING other than the most generic, basic "received wisdom" posted on usenet, or given in equipment reviews and manuals -- or told to you by salesman. If so, my blessings: go and enjoy your hobby! For others who like to know about a diversity of viewpoints: read mine and those of other amateurs and appreciate the variations. -- srw

Update, September 2007:  Vindication of my opinion about the uselessness of standard, cheap "starter" gel-cell batteries came from none other than the store manager of the company that sold me originally the C-11 telescope. This particular gentleman owns a large Astro-Physics mount (and high quality refractor), a laptop, and a very fine CCD imager, and produces professional quality astro pictures, using mostly a high altitude site in Nevada. His trips there take usually two days, and he requires portable battery power at this rural site to run all of his equipment for about the number of hours that I also require on my astro-jaunts. I asked if HE used the gel-cell 17AH battery system that his employer sells, and was told "of course not: it doesn't have enough capacity." In fact, he employs no fewer than three large, heavy AGM marine batteries, each with over 100 amp-hour capacity: one for his scope's mount; one for his laptop; and one for his high-current CCD imager. These batteries have just enough 'poop' to run the equipment for his two-day imaging trips.

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Tuesday 18 July 2006, last edited Thursday 18 September 2008 at 1:24 pm. Copyright © 2006-9 Stephen R. Waldee - All Rights Reserved. All Trademarks or Copyrights are © or Property of Their Respective Copyright Holders.