Crash90

My Feedback: (17)

There have actually been people using unregulated lithiums on the hitec 5945 with success. The hitec 5955 although only rated to 6V is ,with exception to the case, identical to it's cousin the 5995 which IS rated at 7.4 V. Smart-fly has a nice setup that offers regulated power to the Rx and unregulated power to the Servos. That's the direction I am going in with the 2.6.

Now, the weak point seems to be in those connectors. Gotts to upgrade.

Mike3579

My Feedback: (56)

I think deep cycle marine batteries could solve all your problems. think about it there 12V only way 50 lbs! Now how many flights could you get with that kind of power. LOL

Volfy

My Feedback: (23)

About internal resistance... every cell is different. Some of GP's newer ultra high capacity Sub-C and AA cells have internal resistance so low they can withstand very high charging current without overheating. This comes from a very good friend of mine, who is a semi-retired Gold Peak (GP) engineering manager. They are able to develop 15min charger for the 2400+mAh AA cells - that's 10+A charge current - while the cells remain cool to the touch. Sanyo may have been the golden standard in years past, but GP (and others) are outdoing them these days.

As for 7.4V-rating and higher current handling... that is my hope too, but I am not holding my breath waiting for it. the RC electronics industry by nature is very slow to respond to changing market dynamics. All the legacy products out there dictate that manufacturers conform to old convention, or risk alienating the majority of the customer base. The RC radio connector and wiring form factors were developed some 30~40 yrs ago and will likely stay the same for some time to come. I hope I'm wrong about this, and the majors will get together to agree on new standards and specs.

LiPo chemistry holds enormous potential (pun intended), it's choking it down to conform to antiquated specs that's the problem. If the day comes that I can plug 2-cell LiPos directly to my RX, I will retire all my NiMH in an instance.

Volfy

My Feedback: (23)

Yes and no. The 3A rating is continuous. It will pass higher current for short durations, without overheating and causing damage. Servos loads are by nature short bursts or highe current loads, so typically this is okay. However, if you have 14 ultra high torque digital servos all dancing at the same time while you do wild 3D stunts, the aggregate sustained current draw WILL easily overload a convention RX wiring system.

I build my own wiring harness and bus boards - it's really not that difficult if you are somewhat decent at soldering. Plus my custom harnesses have charge ports are all the same for RX, ign, and TX, which makes field charging very easy.

Crash90

My Feedback: (17)

It appears as though that day MAY be here. There are peole successfully running hitec digis along with futaba Rxs on 2s lithiums unregulated.

The folks at troy built are also experimenting with this setup. Maybe you can contact them to see what their findings were. I talked to them maybe 2 weeks ago and they said that the bench runs have been successful.

Nobody including Hitec supports 7.4 V on their servos. My guess is that they would like for us to do their field testing first.



Just for the record. I am NOT one of those people who have tested unregulated lithiums. So, take my statements for what they are worth.

ptgarcia

My Feedback: (36)

I don't see why 7.4v compatability would hurt older equipment. Building receivers and servos so they can handle 7.4v won't make them unable to handle 6.0v or 4.8v. If I'm not mistaken, the receivers are already okay with 7.4v, its the servos that are the question mark.

Crash90

My Feedback: (17)

Agreed. One of the concerns with 7.4V systems have been the higher current draw but lets face it, the 5955 will unofficially put out over 400oz of torque at 7.4 V. There is no need for 7,8,9 and 10-12 servos in our 33-35-40% planes. A 2,6 composite can be run with only 6 servos. probably drawing less current than the alternative 6V system. JMO.

sillyness

My Feedback: (25)

My understanding is that a heat-sink is dumping wattage by reducing the VOLTAGE, not eating available current. A 2200 mAh battery reg'd to 6V will deliver 2200 mAh of current to the servos at 6V.

Using approximations, since the batteries average 7.9V (halfway between full charge and nominal voltage), you lose 4.18 Watt-hours to the heat-sink, and the servos get 13.2 watt-hours (using P=VI). But... 2200mAh should still be delivered at the reduced 6V.

So... the net effect... your system never sees the full energy density of a LiIon pack, but it does see the full current providing capacity.