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LIthium ion power for goto systems?...

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#1 PapaPlanets

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Posted 29 February 2012 - 05:05 PM

Hi,

It seems crazy to me that goto systems are generally powered by lead acid batteries like the celestron powertank.

So what are the lithium ion options? How many amps does a CG5-GT require? (going to check out the manual on their website now)

Is anyone using a l-ion power source?

What about something like this?
http://www.amazon.co...30471008&sr=1-4

And alternatively how long does a set of eneloops power one?

Cheers

#2 Don Trinko

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Posted 29 February 2012 - 05:32 PM

IMO; Price is the reason most use gelcell or lead/acid. Li would be lighter but more expensive.
I do not know how much power they use but a 7 amp hour gell cell will last for hours so for me a 7 amp hour Li battery would be fine.
I do not do any "all nighers" but I suspect that 7 amp hour would last all night unless you have accesories like lap top, dew heaters ect.. Don T.

#3 PapaPlanets

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Posted 29 February 2012 - 06:27 PM

Reading up it seems like the CG5-GT draws 1.5A @12V, so I think that l-ion power pack 10000mAH I linked above will do the job.

Why isn't everyone using them? Half the the price of a 7AH powertank and the size and weight of a laptop battery. There must be something wrong, but I dont see what? :confused:

#4 mclewis1

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Posted 29 February 2012 - 07:00 PM

Starizona sells a compact LiPo power pack for goto scopes. It's benefit is that it can ride on the base of a Celestron CPC or SE scope thus preventing cord wrap issues.

The primary benefit of Lithium batteries is size which normally isn't really important for most goto scopes therefore gel cell lead/acid batteries have a cost/benefit advantage.

The CG-5 draws over an amp when the motors are slewing at high speed, the 1.5 amp is considered a worst case situation. For the majority of the time as it's just tracking it's drawing something under .5 amps. This is a similar situation for many other goto scopes as well.

#5 PapaPlanets

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Posted 29 February 2012 - 07:26 PM

In the UK a 7AH external laptop battery costs £50 and a 10AH, £60.

The 7AH celestron power tank is £80

A cheap lead acid car battery starter is £50

It just seems, in the UK certainly, like it's a no brainer.

#6 mclewis1

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Posted 29 February 2012 - 10:37 PM

It appears that in the UK you can get jumpstart type of batteries that have more than 10amp/hr capacities and include the charger for less than £50.

If you buy an external laptop battery you also may need to adapt the power connector for the mount (2.1mm x 5.5mm for the CG-5).

But your point is well taken ... there are now more inexpensive Lithium battery options that can be used in place of the more traditional batteries.

#7 orlyandico

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Posted 29 February 2012 - 11:05 PM

I think the issue is that a lithium battery needs a specialized charger.

You can't just buy a laptop battery and expect it to charge when you connect it to your cheapo 12V power supply.

Companies like NatSemi make dedicated lithium battery charger control IC's.

http://www.national....2.html#Overview

An improperly charged lithium battery can catch fire or explode.

#8 PapaPlanets

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Posted 01 March 2012 - 05:51 AM

The battery pack I linked to comes with a charger. Here's another option:

http://www.allcam.bi...al_battery.html

#9 ion

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Posted 01 March 2012 - 08:25 AM

Is anyone using a l-ion power source?


Here's a shot of the Tekkeon MP3450 powering an Atlas EQ-G. It is essentially the same size as the hand controller and only weighs a pound. It also includes a tip (B) that fits the Atlas so it can be used out of the box. At 12v the single unit provides 4.25Ahr which runs the mount about 5-6 hours with a moderate amount of slewing. An extended battery can be added that doubles the capacity, but not the charging time, which remains around 4 hours. It's not cheap but the ability to output anywhere from 5v-19v makes it useful for powering/charging many other things:

Attached Files



#10 rmollise

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Posted 01 March 2012 - 08:37 AM

Price performance. At this current level...the battery really should be able to supply several amps for full-speed-ahead slewing and be able to do that intermittently for up to 11-12 hours...an Li is not too practical. What you want is a good 17ah lead acid battery, a jump-start battery, not the problem-plagued Celestron Powertank. One will last for YEARS if you treat it properly. Treating one properly is simple:

Charge for 12 hours after each use.
Charge for 12 hours each month if the battery has not been used.

That's all there is to it. Plenty of capacity for not much $$$. What more could you want?

#11 Midnight Dan

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Posted 01 March 2012 - 10:02 AM

You have to be careful about the voltage level some of these put out. I purchased one very similar to the link in the original post above, and it would not power my scope. The 12V output was more like 11 volts when fresh, and under load it dropped to a point where my mount was not happy.

I ended up using it to power my laptop and it works great for that.

-Dan

#12 PapaPlanets

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Posted 01 March 2012 - 11:47 AM

Price performance. At this current level...the battery really should be able to supply several amps for full-speed-ahead slewing and be able to do that intermittently for up to 11-12 hours...an Li is not too practical. What you want is a good 17ah lead acid battery, a jump-start battery, not the problem-plagued Celestron Powertank. One will last for YEARS if you treat it properly. Treating one properly is simple:

Charge for 12 hours after each use.
Charge for 12 hours each month if the battery has not been used.

That's all there is to it. Plenty of capacity for not much $$$. What more could you want?


I know it's ridiculous, but in the UK lions are cheaper.

So what more could I want?
- Cheaper
- Lighter
- Smaller
- Not having to charge for 12 hours after every use
- Not having to charge for 12 hours every month
- More AH capacity per £

Apparently a CG5-GT uses a max of 1.5A and generally around .5 and the chance of 12 hours clear skies in the UK is 0 ;) and I don't think I'd ever be out for 12 hours anyway.

#13 JAT Observatory

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Posted 01 March 2012 - 01:43 PM

It's not only how they are charged it is how they are discharged. If the internal protection circuit fails and they are run down too low the battery will be damaged and recharging impossible. Over charging can also result in overheating and combustion. They should also be fully charged before storing for long periods because the power required for the protection circuit can cause the battery to discharge below specs.

If you follow the rules, they are great.

#14 frolinmod

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Posted 01 March 2012 - 02:06 PM

Software Bisque sells a lithium-ion phosphate (LiFePO4) battery pack for their Paramount mounts here. It's rather pricy.

#15 mrc3

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Posted 27 March 2012 - 01:48 PM

Lithium Poly or LiFE batteries are very nice power packs but they require a bit more care in use than lead acid.

Things to be aware of:
1) They are 3.7V (LiPo) / cell thus you can go 3 cell at ~11.1 V or 4 cell at 14.8V. A tightly controlled 11-14V range will require a 4 cell with voltage regulation.
2) They REALLY don't like to be discharged too far (typically don't go lower than 3.2V/cell)
3) You need a special charger with a constant current with a voltage cap of 4.2V / cell. Over charge it and you run the risk of the cell exploding. With multicell packs LiPo chargers typically use a balance connector to ensure that no individual cell is overcharged.
4) Cells have less capacity when cold (like many batteries).

Pretty much all of the self contained Lithium battery based powersources such as the Tekkeon shown above have most of these issues already addressed with a self contained charger and low voltage cutoff circuit. But if you get the raw battery from a hobby store or R.C. model vendor online, be aware of the listed issues.

The batteries themselves have come down greatly in cost. For example a 4 cell 5 AH LiPo battery costs around $35
http://www.hobbyking...Warehouse_.html

And can be recharged in as little as 30minutes with a proper charger.

Mike

#16 James_826

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Posted 29 March 2012 - 02:18 PM

Another option is lithium ion nano phosphate batteries. They are made by A123. The hold a charge for a long time, and can you can pull allot of amps off them with out damaging the batteries. I got mine from here:
http://www.buddipole...tablepower.html

#17 Chris Purves

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Posted 08 October 2012 - 02:37 AM

Sorry to raise up an old thread but I have been thinking about airline portable power for my Takahashi Em-11 mount. It seems that the vast majority of decent sized batteries are no-go's on airlines. What do seem acceptable are this kind of thing (av batteries for video cameras)

http://www.blueshape..._bv100.asp?lng=

as long as the batteries are < 100Wh they are OK on flights

You can take a few of them on a plane and some of the models connect/snap together to give you 'double' power (same voltage).

Although not cheap they do seem like a solution to how to power a mount for airline travel.

Anyone tried these ?

Chris

#18 Jarno

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Posted 08 October 2012 - 02:26 PM

I've just ordered a Deben Tracer 8Ah LiPo battery to power my Astrotrac TT-320X. They have several models ranging from 8Ah up to 22Ah. They come complete with mains charger, car charger, cigar plug output connector and a carry bag. I'll report back once it gets here, maybe the bigger capacity models will fit your needs.

#19 James_826

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Posted 08 October 2012 - 03:24 PM

I have had very good luck using these batteries for my ham radios, A123.
http://www.buddipole...tablepower.html
These are lithium ion nano phosphate, they are a little pricey and need a special charger, but very light weight batteries.

#20 astro_baby

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Posted 11 October 2012 - 05:46 PM

Somone I know had a super compact battery which I think was lithium ion, it worked fine on a Nexstar but just wouldnt cut it with an EQ6.

After much messing about it turned out when it got cold it dropped voltage and as the six is a very unhappy mount if it doesnt get what it wants..ie a steady 12v He dumped it in favour of a conventional lead acid.

It was a very compact battery and on its spec sheet it seemed like it would do the job...unfortunately in the field it was a different story.

Unfortunately he has since departed for Singapore so I cant ask where he gor the battery from or its precise specs.

I use a 23ah gel battery and its been fine for 2 years. Keeps the mount, dew straps etc running all night and its quite light and compact.

#21 aamilo

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Posted 11 October 2012 - 06:24 PM

Been tempted at buying this for my CPC800.

http://www.ebay.com/...984.m1423.l2649

It just seems too cheap to risk my scope electronics on. ;)






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