A123 Batteries for Dummies.

[Pale Rider]

Just tried out a single A123 cell on my Ch ignition..after 60 min of flying the voltage drop was only .07...Thats after 5 12 min flights..started at 3.36 and ended at 3.29

[Kiwi]

Now thats opened up another avenue. These cells certainly have the grunt.

The only bummer I have come across is on my EVO 50 Heli. The 401 gyro is cool for 6 volts but the danged servo is only rated at 4.8 volts. Its one of those fancy dangled Futaba 9254 I think it is and its nor for 6 volts period.

Who makes a single servo inline regulator so I dont melt this thing or does someone have some ideas to help me out here.

[dick hanson]

what is a futaba?

[Kiwi]

Its a very expensive Radio in my case that they say will be 2.4 Ghz capable one day. Note I did not say soon Dick.

Found the inline regulator for the servo. $4 but two weeks to get it here, dang dang dang!!!!!

[hybris]

The MPI inline regs would work for the servo but it is a little overkill. It is only .4oz according to the ad. It is the one on top.

http://www.maxxprod.com/mpi/mpi-21.h...lt%20Regulator

[sengle]

Hi (Fellow) Kiwi,

A source of the stepdown regulator closer to home:

http://www.rchelis.co.nz/product_inf...roducts_id=795

Cheers,

Steve...

[MalaysianFlyer]

Finally got my A123 cells and managed to solder them quite easily. Turns out that under the tabs that you guys see in the Dewalt packs, is a steel disc thats been welded/soldered to the case. Can easily solder to this disc using a high power iron with a large chisel tip. I got the battery bars for the cells from Hyperion. Tested a 6S pack today on a MEGA 22/30/2 with APC 8x8 prop. pulling 60A and voltage stayed constant around 13volts. Throttled down till the current was 25amps and the voltage was 16+volts.

I am impressed with these batteries. Really awesome, and I am confident they will last hundreds of cycles when used as receiver packs.

[DKjens]

Just bought a Dewalt pack on ebai for $100.00 shipped. I will power my new SX with these batteries, and for that I have a question for Kiwi.

Have you used these batteries with a Weatronic unit?

If so, do you tell the Weatronic unit that it is NiCd's?

And if so, is there no problem for the Weatronic unit to detect when voltage goes down on the A123 cells?

Since I am going to use these cells to power servos etc., (9x8711 + throttle) can I use the existing spot welded tabs, or should I solder tabs on? I plan to make 5 x 2s packs from the Dewalt pack, use two 2s packs in p as main battery, one 2s pack as secondary battery, and one 2s pack for ignition and smoke pump.

[dick hanson]

solder to existing tabs -- they will pass 50 amps easily
detecting state of charge in these cells is again --different
you check the voltage without any load - and the TOTAL cell varience from nominal full to end of charge (end of full effective power) is only 3/10s of a volt 3.3--3.0
in running packs from full to almost flat in the air at 40 amp loading - -I am using the cells for electric power -- I see 2000ma as the USABLE mah from ma 2300 mah pack
you will have to use a setup for a couple of flights then measure & record mah used -a few times and soon you will see the time to voltage drop relationship.
at 3 v per cell it is at th e end of pack befor th power dropsof rather quickly.
until then the power output is strong (voltage output at high amperage is very good.)
your biggest problem will be connectors ability to pass current at very high loads
You will never overload the cells -the wires would go "poof" first.

[Kiwi]

Jens.

No I have not used the A123 cells on the Weatronic Rx but thats on the drawing board. I will set it to Nicad as the battery setting because the fully charged cells are closer to NiCd than Lipos. I really don't understand what difference it will make other than the alarm lamp maybe flashing once your cell voltage drops below five volts. If you set it to LiPo I assume the alarm light will go off at 6 volts as that is the low battery alarm point for that chemistry.

On another note I hope to have my new balanced cell chargers here mid September. These are on the way for some testing and they are rated at 10 amps. Full cell balancing and they balance the cells with up to 1 amp differential. These things promise to be super fast to recharge the packs and can handle up to 6S A123 and the 10 cell 10S charger is on the drawing board as well. Same thing, 1 amp differential cell balancing.

These things are not available on the market yet but they will be once the testing phase is over. As soon as I know these things are go I will let you know but until I get some to smoke up this is all gossip.

[aerohead]

	Quote: Originally Posted by Kiwi
	Now thats opened up another avenue. These cells certainly have the grunt. The only bummer I have come across is on my EVO 50 Heli. The 401 gyro is cool for 6 volts but the danged servo is only rated at 4.8 volts. Its one of those fancy dangled Futaba 9254 I think it is and its nor for 6 volts period. Who makes a single servo inline regulator so I dont melt this thing or does someone have some ideas to help me out here.

Align,the heli guys---works great

[Kiwi]

Aerohead,

Got it today. We are set to go, now all I need is my bleedin charger.

[dick hanson]

for those why may care ---
I tested a 2 cell pack today as follows:
full pack (filled to 2335mah) -applie dual 1157 light bulb load (3.5 amps starting load) for 37 minutes --which brought voltage to 5.7 volts aprox.
so what?
What I was looking at was a 3500 ma load applied against 2300mah (65% of 3500)
and found as expected it was ready to give up at almost 39 minutes 39/60=65%.
the 3.5 constant load showed 5.7 as lowest voltage under 3.5 amp (aprox) load over effective charge life (2300ma) removing the load - cell reading bounced back close to 6 v .
so what?
It said, that till the unloaded voltage gets down to 6 volts-- the pack will sustain a 3.5 amp load to deliver about 5.5 volts .

That is about all the load the std crimp connectors will handle with out warming .
IF I had a dual pack-4600mah-- I could easily handle any servo loads on a 40% model -- for a long time - -I don't know anyone who had flown a big model with a complement of JR 8711 servos and used an onboard recorder to measure actual ongoing draw- - so I can't say what the actual times and final voltages may be.

[Rolling Thunder]

I have a Aeroworks 35% 260 with 8 8711 servos and a Medusa Research Oracle unit. We were testing the Smart Fly Power Expander Sport to see how hot the voltage regulators got. I also recorded amp draw. I have records of 10 minute flights from basic to Unlimited sequences and also some 3d flight. The only time the amp draw was over 1.5 was in snap rolls.

All the ganged servos were matched with equalizers (rudder,ailerons). All the surfaces have 45 degrees of throw at 135 ATV on the 10X.

[Pale Rider]

So Dick, what would you say a safe no fly voltage read would be--unloaded-----6.4v ? when I apply a .5A load to that it goes to 6.0v