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ramboman -> a123 experience (2/14/2007 5:11:55 PM)
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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...
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