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geministar

Celestron Power Tanks - Capacities; Disadvantages

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For my Nexstar 127 MCT I currently have 3 sets of 8xAA Duracells - one onboard; two backups.

I'm considering a Power Tank however.

Can anyone please advise me about roughly how long you can get from a 7Ah and a 17Ah capacity tank?  (There's a big jump in price.)

Also, I've read reviews stating that these things are "delicate", shouldn't be run down low, and don't last all that long anyway.

I'd like to hear of your experiences with Power Tanks.  Thanks!

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The main brand power tanks are way over priced - go to a good electrical store (eg Maplins) and you'll get the same thing for half the price. It won't have a radio, flashing amber light, or air compressor etc - but you don't need those for astronomy anyway.

I've had two power tanks for the last 5 years and they never let me down. I had a 17ah in one of them which I forgot to charge over 6mths and ended up replacing it with a 20ah one - but that was my fault. I now top up with an 8hr charge after each session and a full charge every 3mths if not in use. A session will last all night and well into the morning if only driving the mount. I use mains power for other requirements like dew control and cameras. Very cold weather can halve the time spent in the field.

Forget the Duracells - you'll be lucky to get an hour out of them and you'll soon spend as much replacing them as you could otherwise spend on a rechargable power tank. Well cared for a power tank can last for years. :)

(My current power tanks are 20ah and 17ah)

Edited by brantuk
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Thanks, brantuk.  If I got a battery from Maplin's, I presume I'd have to factor in the cost of a charger, and the lead from the battery to the 'scope.  

Would that still be less than £54 for a 7Ah from FLO or Wex, I wonder.  

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It would seem that the problem with the power tanks is you're paying for a name. I recently bought a 12v jumpstart kir from Halfords for £39. Worth every penny. Comes with 17Ah battery, two 12v outlets a sub outlet and an LED light. What it didn't have was a red light, but got one of those from B&Q for £3. Can't tell you how pleased I am with it. And on the plus side if your battery goes flat you can go out and start the car. Don't think the power rank has that ability.

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Thanks for all the advice, much appreciated.

Yes, Duracells - even with plenty of backup - are not great, and at £4 a throw would soon run up quite a cost.

Didn't know about jumpstart units that you just plug in to charge, and that have 12V DC O/P sockets and leads that terminate in a plug that fits the 'scope!

So I've bought a Phaze jumpstart unit (17Ah) from Halfords, marked at £60, but sold to match the online price of £39.  (Normal price £80.)

Fully charged in no time, tried out, works a treat, and also has a bright onboard lamp if needed.  Maintenance minimal.

(Thanks for the tip on that. Staffs O.)

Anyone want to buy some 8-way AA battery holders??

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I bought one of those jumpstarter bits of kit for a mate on eBay £24.99 and free p+p bargain!

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Most of the halfords/maplins ones come with a charger included. The key is to make sure you look after them and never let them drain down to zero (otherwise there's a good chance of ruining it). :)

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Most of the halfords/maplins ones come with a charger included. The key is to make sure you look after them and never let them drain down to zero (otherwise there's a good chance of ruining it). :)

Instructions are really clear on keeping them charged.

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Thanks for all the advice, much appreciated.

Yes, Duracells - even with plenty of backup - are not great, and at £4 a throw would soon run up quite a cost.

Didn't know about jumpstart units that you just plug in to charge, and that have 12V DC O/P sockets and leads that terminate in a plug that fits the 'scope!

So I've bought a Phaze jumpstart unit (17Ah) from Halfords, marked at £60, but sold to match the online price of £39.  (Normal price £80.)

Fully charged in no time, tried out, works a treat, and also has a bright onboard lamp if needed.  Maintenance minimal.

(Thanks for the tip on that. Staffs O.)

Anyone want to buy some 8-way AA battery holders??

You're welcome. It was the retailer of my telescope who told me about them. And then he went on about golf cart batteries.

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The Phaze unit recommends charging after every use. And at 17Ah, you'd have to go some in a session to drain it!

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Depends what you hook up to it and what the temperature is outside as to how long it will last. Just driving the mount it will go on all of most nights. But if you add a couple of cameras (with guided imaging), and 3 or 4 dew bands, half a dozen powered usb leads and an EQmod, you can drain 17ah in only a couple of hours in the cold.

Not to mention the tracking and goto accuracy problems as the current drops just below 12V. That's why I only ever use the battery packs to drive the mount. Golf and wheelchair batteries are good too - but judicious use is the key. :)

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I have the 12V. & 17Ahr. branded Orion (USA). It's more money - true. But it's also very convienent for all emergencies. Now that we've had tornados in New England, you really need to be ready for things we never would have believed 10 years ago. If I pick up another, I'll go for low-cost. But if you've got one of these - keep it fully charged at all times. You may need to loan it to a neighbor even if you don't need it. And it's very easy to use.

Dave

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Depends what you hook up to it and what the temperature is outside as to how long it will last. Just driving the mount it will go on all of most nights. But if you add a couple of cameras (with guided imaging), and 3 or 4 dew bands, half a dozen powered usb leads and an EQmod, you can drain 17ah in only a couple of hours in the cold.

Not to mention the tracking and goto accuracy problems as the current drops just below 12V. That's why I only ever use the battery packs to drive the mount. Golf and wheelchair batteries are good too - but judicious use is the key. :)

All good points, thanks for the info.  At present, I just drive the mount!  (Then use the bright lamp at the end to pack stuff away!)

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I bought a 17ah jump starter from tesco for £50 and had a 5 hrs session last night with it still going strong but had stop due to rain. I have the avx mount.

Sent from my iPhone using Tapatalk

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I have two power packs, one a celestron with the battery replaced to a 22ah golf battery. 

Re: charging. Some chargers can be left on permantly without damaging the battery, refer to the manual to see if this is the case though. If not every month for a day will keep it tip top.

Steve

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I have a 34Ah power pack, it has the usual outputs with an added 3-way extention, a light (converted to red using some red foil) and an inverter. It is fairly heavy but it has the extra capacity of the larger battery so more weight is only to be expected. Easy to move around with the handle though.

DSC00210_zps20bb5a09.jpg

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I have a 34Ah power pack, it has the usual outputs with an added 3-way extention, a light (converted to red using some red foil) and an inverter. It is fairly heavy but it has the extra capacity of the larger battery so more weight is only to be expected. Easy to move around with the handle though.

DSC00210_zps20bb5a09.jpg

This was once used to power the hubble telescope so no probs there then  :wink:  :grin:

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Hi,

I have had the Celestron 17aH power tank for a year now.  The longest I have used it in one go is 6 hours and it hasn't run out juice.  That is using it to power the scope (Nexstar 8SE), heated dew shield for the OTA and a heated band for the eyepiece.

Downside - I went 5 months without using it and it almost killed the battery (summer in the Shetland Islands - not many stars to see from May to September).  I invested in a Noco Genius 3500 smart charger from amazon for £45 - it had a repair setting for dud batteries and worked a treat.  It also has a smart trickle charge setting so you can leave it connected indefinitely without worrying.  It has connections to attach to the positive and negative terminals on the power tank.

So if you have the cash I would go for a good quality power tank, but save some of the cash for a smart charger as well  - it will prolong the life of your tank.

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It is usually recommended to go for deep cycle batteries rather than jump starter as Marine batteries have the advantage of being able to repeatedly handle long periods of use (discharging) Starting batteries are made for short periods of high current use followed by recharging. If they are repeatedly used for long periods as with a scope, they will not last as long as a marine battery...

And there is always this :)

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Hi,

I have had the Celestron 17aH power tank for a year now.  The longest I have used it in one go is 6 hours and it hasn't run out juice.  That is using it to power the scope (Nexstar 8SE), heated dew shield for the OTA and a heated band for the eyepiece.

Downside - I went 5 months without using it and it almost killed the battery (summer in the Shetland Islands - not many stars to see from May to September).  I invested in a Noco Genius 3500 smart charger from amazon for £45 - it had a repair setting for dud batteries and worked a treat.  It also has a smart trickle charge setting so you can leave it connected indefinitely without worrying.  It has connections to attach to the positive and negative terminals on the power tank.

So if you have the cash I would go for a good quality power tank, but save some of the cash for a smart charger as well  - it will prolong the life of your tank.

Thanks.  The "Phaze" jumpstarter from Halford's is a pretty good unit, with a lamp, 2 x 12v DC o/ps, and a USB 5V o/p, not to mention the jump leads!  Normal price, £80, which is only a bit less than most suppliers sell the Celestron 17Ah Tank for.  I paid £39, which was good, and launched it this morning.  

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It is usually recommended to go for deep cycle batteries rather than jump starter as Marine batteries have the advantage of being able to repeatedly handle long periods of use (discharging) Starting batteries are made for short periods of high current use followed by recharging. If they are repeatedly used for long periods as with a scope, they will not last as long as a marine battery...

And there is always this :)

Yes, there is that distinction.  The makers recommend charging after every use, so I'll do that and see how it goes............

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If I were to have the four years since I took up this frustrating and rewarding hobby again...I would not buy my Power tank again (a 17Ah SW)...

Despite not being inexperienced with Lead Acid batteries and being well aware of the need to keep them topped up at all times...the rather confusing LED charging light system on my PT conspired against it.

Basically I was undercharging it, which killed its useful life.

I have now switched to a 100Ah leisure battery with a smarter charger which works very well in my semi permanent setup.

Probably not practical for those who travel to the wilderness to observe though.

I am sure I could pick up a 100Ah leisure battery and a smart charger for the same price as a 17Ah PT...although I wouldn't be able to listen to the radio and dance around to flashing red lights at 3am though...

Steve

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