2s 6.6v A123 reciever batt? - RC-Monster Forums

zeropointbug · **2s 6.6v A123 reciever batt? -** 07.03.2009, 02:14 AM

Hey, I have 2 A123 cells here that have not seen discharge currents in 2 years... I cycled them a few times and they deliver about 2100mah @ 2.5v cut-off (720i)... I am doing some discharge tests on them at 1, 2, and 3 amps discharge. They are all around 3.3volts steady.

So, i ask, is it a good idea to use it as a receiver pack? I know you can get 2s lipo specific servos now, such as the Hitec 7740TH...

http://www.hitecrcd.com/servos/show?name=HS-7940TH

So a 6.6volt pack should be about 200oz/in torque and 0.065 sec @ 60deg.... extremely fast servo.

Anyways, can a Spektrum DX2 receiver handle the extra bit of voltage?

lincpimp · 07.03.2009, 02:32 AM

I do not see why not, a fully charged nimh 5 cell can beat 6v...

zeropointbug · 07.03.2009, 03:41 AM

Aight, just making sure.

What do think the runtime would be on it? Have you ever ran Rx batts?

I would like to try this, because I had unexpected shutdowns at the races, and I think it was my BEC doing it.

whitrzac · 07.03.2009, 10:05 AM

I have run the 1100mah ones as RX packs, no problems

zeropointbug · 07.03.2009, 02:12 PM

Awesome thanks, some real experience... I am going to toss the BEC, and try em out.

Metallover · 07.03.2009, 02:27 PM

One guy put two LEDs on something to drop the voltage from 6.6v to 6v. I don't know if it's needed, but it's just an idea. A fully charged a123 pack has to be over 7v...

zeropointbug · 07.03.2009, 03:46 PM

~7.1volts off the charger, but for this application, I could just use a lower charging voltage (3.5v) so it's 7.0 volts, then I fairly rapidly drops to 3.3volts/cell or 6.6volts for almost the entire discharge.

Also should be zero electrical noise using a pack, might help with radio reception at distance?

Weights 150 grams, BTW.

Do you guys think the 7940TH is a good racing servo? Running off this pack, it should twist around 200 torque, and 0.065 sec transit. For a Revo.