Lipo or A123 for HV servos

[Soarntz]

I'm putting together second Blanik that has been sitting in the box for over two years... I was letting the epoxy and paint cure!

Anyhow, I have HV servos and am interested in thoughts on Lipo vs A123. I have used A123'for several years and like them. However, the HV servos can make use of 8.4 Lipo voltage. Perhaps I don't need for the Blanik. Thoughts?

Dave

[Sinkhappens86]

We've used A123s on my Dad's Blanik and the servos have had plenty of torque. I don't know that you'll see much of a difference with Lipo vs A123

[lenb]

Hi Dave.
123"s are a solid choice, but limited in capacity choices. You also need to pay very close attention to the usage since the fall-off is like stepping off a cliff.
These new packs look good, I recently bought a couple. http://www.horizonhobby.com/SPMB4000LFRX
They give big capacity at reasonable cost.

Lipo are very good and you get the extra horse power and capacity choice. Downside of course is the volatility to charging and damage.

[Celuft]

Len, that battery has some grunt, good choice

Carl

[Soarntz]

Yeah, it's back ordered now....

[Soarntz]

Though, I'm in no hurry

[Stew2]

Dave, Can you get A123's in packs greater than 6.6V? I thought that A123 cells were 3.3V each, I believe to utilize the torque capability of HV servos, you need 7.4V. I certainly could be wrong. I use Li-Ion 7.4V packs for my HV setups and most guys use 2S Li-po's. I don't have any hands on experience with the Blanik, but from what I have observed, I would put HV servos on the flaps, and with not being a fan of splitting up servo voltage, if one servo is HV, then I go all HV in the airplane. But all of that is simply personal preference.

Scot

[Swiss1]

I have A123's in the Antares, They charge very quickly but as Len said they drop off quick and I don't like that! Lipos are the better solution but my choice is to use Nihm's, I hear you laugh as it is old technology, but think about it you can make up any size in 1.2V increments and as you are going to add nose weight anyway I would rather use it in the power source. Once charged I can fly my planes with a Spektrum Power Safe receiver and two 5000mah batteries for 2 days without the worry of low power
My 2 cents worth.

Jeremy and Ben
SCCAAA TT TN

[Stew2]

I don't think there is anything wrong with Nimh, but how do you get to 7.4V in 1.2V increments. On the other hand, does the 0.2V shortfall really make a difference? Not a great one. I bet the torque reduction is a direct ratio of the voltages. I choose Li-Ion batteries because of the lower/almost non-existent probability of fire while charging or crash. The consequence is cost, they are not inexpensive batteries. I use Duralite Sentinel series.

[Steve P]

Cheapskate who now goes with big 2S Turnigy NanoTec LiPos. Still many planes with dual 5000 mAh 5S NiMh packs.

BTW! Becoming a huge fan of the JR NX8931 servos. The new JR line operates on a range of 4.8 - 8.5V at 319 - 506 ounces of torque.

[Soarntz]

thanks for all you thoughts.as you know, i don,t fly "non-stop" so i can easily top off the A123's.. how does the lipo battery perform in the cold weather as a flight battery?

[Steve P]

No real issues I have found for Lipos in cold weather for RX use. We are not pulling a high C rate from the packs. I really don't fly often in frigid weather.

[Swiss1]

I don't think there is anything wrong with Nimh, but how do you get to 7.4V in 1.2V increments. On the other hand, does the 0.2V shortfall really make a difference? Not a great one. I bet the torque reduction is a direct ratio of the voltages. I choose Li-Ion batteries because of the lower/almost non-existent probability of fire while charging or crash. The consequence is cost, they are not inexpensive batteries. I use Duralite Sentinel series.

Dave said they can handle 8.4V, so that would be 7 cells

Jeremy and Ben
SCCAAA TT TN

[lenb]

Never had a problem with the cold and lipo's, but like Steve said, we don't require high discharge rates

[Soarntz]

Thanks Len, that's what I was thinking....

[Soarntz]

If it's frigid I'm likely looking to slope

[Csessa]

Don't forget to drop the voltage for the spoilers. They can only handle 5V.

[Steve P]

Don't forget to drop the voltage for the spoilers. They can only handle 5V.

http://www.horizonhobby.com/product/radios/radio-accessories/miscellaneous-15069--1/2-channel-voltage-regulator-jrpvr5203

[Soarntz]

Yes, I have a couple of these, thanks Connio and Steve