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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> a123 experience
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a123 experience - 2/14/2007 5:11:55 PM   
ramboman


 

Posts: 34
Joined: 12/16/2004
From: waterloo, AR, BELGIUM
Status: offline 		I like big planes but I dislike fuel; electic is my way.
Big 30s NiCd and NiMh are now replaced by LiPos but charging in the field is not practical,
there is no charger on the market to refill a 8s2p 3700mAH at 2.5C (FlightPower).
So I went to a123, to be refilled at 10Amps in 15min, but still no charger ;-(
I tried the following, it works !
- using 10 * 12volts 7.2amps lead batteries coupled either as 1s10p for 12volts or 2s5p for 24volts (switch)
- under 24 volts, I charge a 6s1p a123 pack thru a 0.51ohm 50watt resistance at just less than 10amps without any charger
- just hold an eys on the wattmeter to see that voltages equalizes after 12 to 15min
- amperage drops automatically to 0.5amps, it's then useless to go further...
- I did it under 24volts because the MEC pack add to have a pair number of cells
- now I got 3s2p packs from MEC that can be loaded under 12volts, just change the resistance
- or use an appropriate lenght of wire to limit the amperage to 20amps (2p)
Limitation
- I have to work with 3s or multiple of 3s packs; 3s equalize a 12volt lead battery
- Lead batteries are to be large enough to refill many times the many a123 packs...
Application
- I got 6 a123 packs, 4 times 6s1p and 2 times 3s2p that can be coupled as needed:
- as 6s6p to be refilled at 60amps under 24volts thru 6 resistance in parallel
- as 9s4p to power a Cyclon Elite 24 (replacing 8s2p 3700mAH LiPos) on a BigLift II
- as 12s3p to power a Cyclon 160 thru a Phoenix HV-110: 2500watts continue power...
- using Dean plugs, reconfiguration is very easy.
Next
- I load a123 packs at home using a CCCV power unit, 50volts 20amps
- Using a generator (there is no main in my club) I can do the same in the field
Conclusion
- The whole power chain is equivalent in power and in weight with a US engine 41 with fuel
- I can use it for my giant P-47 in construction
- using a 4-blade 24" propeller ;-)
The only problem is the size of my car...
       Post #: 1

RE: a123 experience - 4/26/2007 6:54:48 AM   
jasonwang3a



Posts: 69
Joined: 10/18/2006
From: shenzhen, CHINA
Status: offline 		i am interested in your charging method, could you tell me wha is your a123 battery pack capacity, it is best to upload some images of connection between lead acid battery and a123 battery.

thank you,

contact me, jasonwang3a@163.com.

_____________________________

Jason

(in reply to ramboman)
       Post #: 2

RE: a123 experience - 4/28/2007 7:30:16 PM   
Red Scholefield



Posts: 4733
Joined: 12/8/2001
From: Newberry, FL, USA
Status: online 		This is an extremely dangerous practice. One little misstep and you could be in a overcharge situation where the battery could explode. Use a charger designed for the job not some jury rigged system that can get you in lots of trouble.

< Message edited by Red Scholefield -- 4/28/2007 7:32:09 PM >

_____________________________

Red S. AMA 951
R/C Battery Clinic
www.rcbatteryclinic.com

(in reply to ramboman)
       Post #: 3

RE: a123 experience - 4/29/2007 8:35:47 AM   
ramboman


 

Posts: 34
Joined: 12/16/2004
From: waterloo, AR, BELGIUM
Status: offline 		Words, words, words...
Look at the a123 specs:
- CCCV at 10amps, 3.6volts
Loop at the "dapter+":
- it stops charge at 3.7volts
Using a CCCV power unit:
- 100% within the specs
- but you have to set the pots right ;-)
- for my 10s2p on 20amps, 36volts (it's not foolproof)
Using 3 lead batteries:
- for a specific pack (10s2p)
- current is limited by internal resistance and lenght of wire
- set lenght of wire for appropriate continuous current (20amps)
- voltage is limited by 3 times lead batteries, a123 pack rises to that level max
OK, you cannot charge any a123 pack without thinking a bit,
but give me the brand of a charger that can charge a 10s2p pack in 12min
within the specifications and without risk...
More, you charge the pack in the plane; you don't have to buy a second one,
you don't have to modify in depth a "glow" plane to be able to change
the pack easily...
Just try it...

(in reply to Red Scholefield)
       Post #: 4

RE: a123 experience - 4/30/2007 5:21:22 PM   
MinnFlyer



Posts: 19094
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline 		ramboman, I am glad that you found a way to remedy your situation, however, I would STRONGLY caution anyone who is not extremely knowledgeable about every aspect of LiPo batteries not to follow your example.

These batteries are extremely dangerous when not handled properly, ESPECIALLY during charging. Improper handling can lead to an explosion and/or fire.

Is it really worth the risk?

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to ramboman)
       Post #: 5

RE: a123 experience - 4/30/2007 6:03:05 PM   
ramboman


 

Posts: 34
Joined: 12/16/2004
From: waterloo, AR, BELGIUM
Status: offline 		MinnFlyer,

we are talking about a123, not common LiPos...
I never would try to charge LiPos this way.
You are right to be so carefull.

But with a123, there is no risk at all,
except a pain in the back, with the lead batteries ;-)

(in reply to MinnFlyer)
       Post #: 6

RE: a123 experience - 5/2/2007 12:04:12 AM   
lutach


 

Posts: 27
Joined: 9/9/2003
From: kearny, NJ, USA
Status: offline 		My experience with the A123 cells have shown amazing results. I started using 36 volts on my truck and it is impressive. Here are a few links:

http://www.youtube.com/watch?v=-yrzb2EYsug (I didn't know how much grip the tires had)
http://www.youtube.com/watch?v=9330XxFGth0
http://www.rcpics.net/view_single.php?medid=84494
http://www.rcpics.net/view_single.php?medid=84493
http://www.rcpics.net/view_single.php?medid=84492
http://www.rcpics.net/view_single.php?medid=84388
http://www.rcpics.net/view_single.php?medid=84387
http://www.rcpics.net/view_single.php?medid=84386



(in reply to ramboman)
       Post #: 7

RE: a123 experience - 8/26/2007 1:13:27 PM   
Night_prowler26



Posts: 1059
Joined: 3/11/2003
From: PowderSprings, GA, USA
Status: offline 		you could just by a tunderpower or astroflight charger that will charge at 10 amps, and it be safe then

_____________________________

Mini Edge 540,BP Edge 540 profle ,MST, E rustler ,With DX2.0. /GF"S-E Pede, Blade CX,Slow stick A123 Batts all the way!

(in reply to lutach)
       Post #: 8

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