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Gear / Technical Help => Remote Power => Topic started by: Marcoscine on September 11, 2010, 11:29:51 PM

Title: [HELP]-Li ion Battery question.
Post by: Marcoscine on September 11, 2010, 11:29:51 PM
Hi Folks.
I use this 12v, 9v and 5v Lion Battery (http://cgi.ebay.com/5V-9V-12V-DC-Portable-Rechargeable-CCTV-Li-ion-battery-/320553900286?pt=LH_DefaultDomain_0&hash=item4aa28058fe#ht_4959wt_911) to powerd my TASCAm Dr-680 and MiniMe simultaneously. It's a nice battery with a great life. The only thing that i dislike the battery is the absence of a capacity indicator. I've searched and found this: http://cgi.ebay.com/Battery-Condition-Checker-Smart-Guard_W0QQitemZ280519644838QQcategoryZ34061QQcmdZViewItemQQ_trksidZp4340.m263QQ_trkparmsZalgo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%252BDDSIC%26otn%3D10%26pmod%3D280521145728%26ps%3D63%26clkid%3D5747722899740084189#ht_500wt_928 that i think it's made for toy helicopter LIPO battery. Here is a manual of this thing: http://www.f1hobbies.com/images/documents/pfsbc01.pdf

Anyone know if there is any chance of it working. And otherwise, if there is any other solution?

Thanks one more time. And sorry about the English.
Title: Re: [HELP]-Li ion Battery question.
Post by: sunjan on September 13, 2010, 06:32:07 AM
Anyone know if there is any chance of it working.

The capacity checker is designed to measure each cell independently, that's why you have an interface with 7 leads.
Note that the manual says metering of 2-7 cells - not 1 cell.
Since your battery doesn't have individual outputs from each built-in cell, you can't get multiple readings unless you pry it open.
Maybe there's a way to get an aggregate reading from just one output, but you'd still need to buy/build a custom connector with power cable from your battery.

Here's a similar device, I guess it's the same technology underneath, but they come with more connectors:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250691359795
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270634333087

Caution: Li-ion batteries can blow up if shorted. If you're building a custom cable, make sure you know what you're doing!

Drop a PM to the seller and ask. Judge for yourself if he sounds knowledgeable, or just trying to sell you smth he has no clue about...
Title: Re: [HELP]-Li ion Battery question.
Post by: manleyf on December 04, 2010, 04:58:55 PM
Has anyone found an inexpensive battery similar to the OP's but WITH a built in gauge?
I really think having the on board gauge is important....
thanks,
Manley
Title: Re: [HELP]-Li ion Battery question.
Post by: Roger Gustavsson on December 06, 2010, 07:55:06 AM
How come that there are 5, 9 and 12 V? Is not each cell at 3.7V?

http://en.wikipedia.org/wiki/Lithium-ion_battery
Title: Re: [HELP]-Li ion Battery question.
Post by: headroom on January 03, 2011, 09:24:45 AM
I think it is an internal Voltage converter my 5cents  its soundwise a better idea to have a pure 12 LION Batt
Title: Re: [HELP]-Li ion Battery question.
Post by: lutzr on January 04, 2011, 09:37:57 PM
State Of Charge (SOC) evaluation of cells is one of the biggest challenge of electrical engineering.  You'll find on the net piles of academic articles and EE thesis on that very subject. Here's a good basic introduction: http://www.mpoweruk.com/soc.htm (http://www.mpoweruk.com/soc.htm)

 It's an important problem because in series, a pack has no more capacity than the smallest one in the chain... if one cell drains sooner than the other, the voltage drops and more importantly the internal resistance grows so Amps go down... The Toyota Prius uses more then 200 Ni-MH cells in series for its 273V battery pack!

I myself would stay away from bargain prized Li ion battery packs... those are incredibly reactive chemicals... overcharged (aged, dysfunctional) cells catch frequently in fire. :o

For my project, I'll go with Ni-MH and a good balancing charger. If you really need that energy density, use Lithium iron phosphate cells (aka LIFEPO4 or LiFe cells) from A123 Systems, quite popular in RC circles.

Cell balancing: http://www.mpoweruk.com/balancing.htm (http://www.mpoweruk.com/balancing.htm)
Balancing charger: http://www.sparkfun.com/products/9705 (http://www.sparkfun.com/products/9705)
LiFePO4 cells: http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery (http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery)

Title: Re: [HELP]-Li ion Battery question.
Post by: sunjan on January 06, 2011, 03:45:53 PM
TS.com continues to amaze me, new guys like lutzr pop up from nowhere and contribute with insight and specific knowledge.
T+ and welcome!