Jump to content


Photo

Am I overthinking power tanks?

  • Please log in to reply
37 replies to this topic

#26 ponz

ponz

    Vostok 1

  • -----
  • Posts: 144
  • Joined: 18 Jul 2012
  • Loc: Kansas City, MO

Posted 08 January 2013 - 01:31 PM

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.


I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz

#27 Doug Culbertson

Doug Culbertson

    Skylab

  • *****
  • Posts: 4218
  • Joined: 06 Jan 2005

Posted 08 January 2013 - 01:41 PM

I read somewhere that the Battery Tender Jr. gets really hot (hotter than you'd feel comfortable with leaving it plugged in and unattended), can anyone confirm this? I'd like to replace my 12v charger (a very nice, standard auto/RV one) with a low power BT of some sort.


I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz


+1 I also use it for my 7AH gel cells that I use on my Starmaster, and often forget to disconnect them for days at a time. No problems at all.

#28 CJK

CJK

    Viking 1

  • -----
  • Posts: 555
  • Joined: 05 Dec 2012
  • Loc: Northeast TN

Posted 08 January 2013 - 02:00 PM

I've been using the (same) Battery Tender Jr for several YEARS on my motorcycle batteries and haven't had on problem.

Ponz


:foreheadslap: Doh! Meant to do that back in December when it got too cold to ride!

-- Chris

#29 bobmarleyou812

bobmarleyou812

    Messenger

  • *****
  • Posts: 468
  • Joined: 18 Jan 2008
  • Loc: CA

Posted 10 January 2013 - 09:24 PM

Am I overthinking power tanks?

YES

I have the PSX thing that Costco sells. I can run my scope all night and still have enough juice to put 40 psi in my tire and jump my truck in the morning.

#30 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20507
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 11 January 2013 - 05:35 PM

I think the pricing is way, way too high per AH on the KAIs.

You can get a 66AH Optima Blue deep cycle battery for a couple hundred bucks, a DC plug socket splitter for $10, and a battery Tender Jr. for $17, and have greater capacity in a smaller size than the $950 KAI Titan.

I have a small 7AH KAI pack. Overpriced. It uses a cheap, 7.5AH gel cell like you can buy off eBay for $17. I view the KAI solutions as being for those who are afraid of batteries and clamps. You're paying *a lot* to hide the battery inside of something. :grin:

- Jim

#31 RealSorin

RealSorin

    Vostok 1

  • *****
  • Posts: 146
  • Joined: 22 Oct 2012
  • Loc: Denver, CO

Posted 18 January 2013 - 04:50 PM

I've been trying to understand the battery options and this is a helpful thread. One question I've been pondering in particular: why aren't there many light/compact and plug and play options? I'm looking at this from a consumer electronics perspective where the battery technologies are clearly available, but there don't seem to be many options suitable for driving a telescope.

The PowerTank is heavy and has the issue that the battery really isn't designed for a low draw, or plug and forget charging (without a different charger).

I can across the Goal Zero Sherpa 120, which while expensive, seems like it would work great for a night of observing, and weighs about 4 lbs (lithium iron phosphate cells).

I guess I'm just wondering if there are better solutions I'm not seeing, if this is a gap in the market that people are content to engineer their own personal solutions for, or if nobody else really sees this as a gap?

#32 Steve Daniel

Steve Daniel

    Vostok 1

  • -----
  • Posts: 124
  • Joined: 03 Jun 2012
  • Loc: Austin, TX

Posted 18 January 2013 - 05:23 PM

I'm loving this one: http://www.amazon.co...wms_ohs_product

It will power my Celestron CPC800 all night. I leave it plugged in all the time. Looks like it's no longer available, but there's a 1800 mAh model, which would be about the same as the Celestron pack, I think.

#33 Ricky

Ricky

    Mercury-Atlas

  • *****
  • Posts: 2730
  • Joined: 09 Sep 2003
  • Loc: Nor Cal

Posted 18 January 2013 - 07:29 PM

I'm using a bioenno 12v 12ah lifepo4 battery. It is relatively expensive but its a very safe lithium battery, can be deep cycled well below 50% capacity without damage, is extremely compact in size and weight, and if properly cared for is capable of 2000+ recharge cycles. I've been using it for a couple of weeks now and so far so good...time will tell.

#34 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4569
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 19 January 2013 - 12:56 AM

Ricky,

How much is "...relatively expensive..."

Stan

#35 skinnyonce

skinnyonce

    Vostok 1

  • *****
  • Posts: 197
  • Joined: 23 Mar 2011
  • Loc: ohio

Posted 19 January 2013 - 04:41 AM

115 $ expensive

#36 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4569
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 19 January 2013 - 07:33 AM

Wow,

Maybe I'll just stick to something like this...

http://www.batterysp...ink&product=300

Stan

#37 Ricky

Ricky

    Mercury-Atlas

  • *****
  • Posts: 2730
  • Joined: 09 Sep 2003
  • Loc: Nor Cal

Posted 19 January 2013 - 10:59 AM

Expensive at the start but my batt should last for many years.

#38 EdTheEdge

EdTheEdge

    Surveyor 1

  • -----
  • Posts: 1571
  • Joined: 10 Apr 2009
  • Loc: Lomita, CA

Posted 19 January 2013 - 05:01 PM

Wow,

Maybe I'll just stick to something like this...

http://www.batterysp...ink&product=300

Stan


That does look temptingly promising!






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics