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Celestron PowerTank showing fully charged after use and while charging

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#1 Bosco_Wiggins

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Posted 11 April 2021 - 02:27 PM

My new Celestron PowerTank (12V/7Amp-hour) showed that it was fully charged when it was delivered last week. I still charged it for a few hours, just to make sure I had some charge before viewing with my new Nexstar 6SE last night. While charging, the fully charged light was still lit green, as was the red charging light. I am now charging it again after using it for a few hours last night, but the fully charged light is still on, as is the red charging light. What gives? Why does it seem that the PowerTank is always indicating it is fully charged? Will I damage the battery by leaving it to charge for 10 hours while it is indicating that it is fully charged? 



#2 emflocater

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Posted 11 April 2021 - 04:11 PM

DO NOT USE the charger that came with the Celestron Tank, it will show false light readings. Click HERE and READ POST #2 and it should answer all your questions.

 

Cheers

Don


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#3 TelescopeGreg

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Posted 12 April 2021 - 12:13 AM

The wall wart is probably ok as a charger, as long as you monitor the actual battery voltage.  The lead-acid (SLA/AGM) version of the Tank (NOT the newer Lithium version) should be charged until the battery gets to about 14.1 volts or so, then unplugged.  The challenge is that the charge rate from the wart is so slow, you risk plugging it in and forgetting about it.  The voltage will keep rising, and when it gets into the upper 14's you will start to cook the cells.

 

The "charge done" light comes on gradually, at least on my unit.  I don't know how calibrated they are, and it's very hard to know what brightness corresponds to a fully-charged state.  My recommendation is to get a volt meter (they don't need to be expensive) and monitor what's going on via the two posts at the rear.  As Emflocater said, they're a direct connection to the battery.  A "real" SLA/AGM battery charger can work through them, but I wouldn't use one that designed for a massive car battery.  These little ones are a bit too delicate for that sort of treatment.


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#4 Bosco_Wiggins

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Posted 12 April 2021 - 09:47 AM

Thanks for the great info! I decided to return the lead acid power tank I have and one of the Celestron lithium power tanks instead, which should alleviate some of my concerns. Hopefully the lithium version doesn't need to be charged so slowly and remain plugged in constantly.



#5 blakestree

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Posted 12 April 2021 - 10:19 AM

Whathafudge? I sure am glad I checked this thread. I got one of these, recently, that I haven't used yet.

 

I thank you all, too!



#6 TelescopeGreg

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Posted 12 April 2021 - 11:53 AM

Whathafudge? I sure am glad I checked this thread. I got one of these, recently, that I haven't used yet.

 

I thank you all, too!

{shrug}  This is no different than any other SLA/AGM battery.  They're pretty robust.  Mine is coming up on 4 years old, and it's still working fine. 

 

The only issue is that the "charger" Celestron put into the Tank is, um, "under-featured" in that it doesn't follow a proper charging profile.  That's ok, as long as you monitor things.  Recharge it after use, and turn off the charging once it gets full.



#7 GoFish

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Posted 12 April 2021 - 12:06 PM

I echo the suggestion to toss the OEM charger.  I would just add to smash it to bits with a hammer first lol.gif

 

After killing the battery on a 17ah Powertank by leaving it plugged into the OEM charger for too long, I exclusively use Battery Tender Jr’s on each of my SLA batteries.  AFAIK, it is safe to leave them attached to the battery 24/7 between uses.  



#8 blakestree

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Posted 12 April 2021 - 03:19 PM

I put mine on my Battery Tender Junior and it charged up, quick and easy. waytogo.gif


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#9 t-ara-fan

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Posted 12 April 2021 - 10:46 PM

 

 

The only issue is that the "charger" Celestron put into the Tank is, um, "under-featured" in that it doesn't follow a proper charging profile.  That's ok, as long as you monitor things.  Recharge it after use, and turn off the charging once it gets full.

That explains it. I had one of these.  It failed fast. I am surprised that for the money it has a dumb charger.  What a piece of junk.
 


Edited by t-ara-fan, 12 April 2021 - 10:52 PM.

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#10 GregInColo

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Posted 07 May 2021 - 07:14 PM

I put mine on my Battery Tender Junior and it charged up, quick and easy. waytogo.gif

I just ordered a Battery Tender. what steps do you take when you recharge it with it?

Ordered this one, assume it will work.

https://smile.amazon...uct_top?ie=UTF8



#11 teashea

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Posted 07 May 2021 - 08:52 PM

Buy something that is higher quality.  


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#12 emflocater

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Posted 07 May 2021 - 08:57 PM

I just ordered a Battery Tender. what steps do you take when you recharge it with it?

Ordered this one, assume it will work.

https://smile.amazon...uct_top?ie=UTF8

Read Post #2 to use  HERE

 

Noco Genius 1 is a great smart charger as well! HERE

 

Cheers

Don


Edited by emflocater, 07 May 2021 - 08:58 PM.

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