bruce88123

http://www.smart-fly.com/Products/BatShare/batshare.htm these reduce some of the problems discussed.

CGRetired

My Feedback: (1)

That looks pretty slick, Bruce. I can see this working. If one battery is slightly lower than the other, the higher one is in the circuit until it falls to equal the other one, then they are both in the circuit and drain equally. Pretty slick.

CGr.

bruce88123

And there are switches on the market that fail to the "ON" condition when they fail. You have to unplug the battery to turn off the system. Can't recall the name even though I just saw it this week.

Charlie P.

That's the one I just purchased. ;-) Someone on this forum tipped me off to the "optical ignition cut-off" they offer for gas engines, too, so you can kill the engine without an added servo (straight electrical connections can have problems with the electronic ignition of gassers "pinging" the receiver circuits). Lots of slick items. I got the servo equalizer for a dual-servo rudder hook-up, too.

Hey, it's only money.

bruce88123

Pay a little now or a lot later.

Charlie P.

Yeah. Now if I could just get a hat that slapped me upside the head when I thought about trying a maneuver too low and too fast. D'oh!

bruce88123

Or too slow.[:@]

RCKen

My Feedback: (9)

[link]http://duralitebatteries.com/flight/accessories4.php[/link]

Ken

bruce88123

That's the ones I was thinking of and I believe there are others available too.

CGRetired

My Feedback: (1)

Ken or Bruce:

The RX batteries shown on that web site are Li-Ion or Li-Poly battery packs. Their nominal voltage is 7.4 volts. The TX batteries are a nominal 11.1 volts.

How do the systems handle that? Are they capable of 'self regulating' that excess voltage? I thought the upper limit was just about 6 volts.

Dick.

B.L.E.

The guys who power their servos with li-po or li-ion batteries allmost always use a voltage regulator to bring the voltage to a steady 5 or 6 volts. I use a UBEC on my electric so that I can power the RX and servos with the same 22.2 volt battery that powers the motor.

pupmeister

[link=http://www.fromeco.org/]Fromeco[/link] also make the [link=http://www.fromeco.org/abadger.htm]Badger Switch[/link] that is fail safe. If you are looking at this type of switch you are most probably looking at using li-ions on your plane, in that case MPI, Duralite, Emcotec, Smart-Fly and various others make regulators that include fail safe switches built into them. One thing to remember is that all these fail safe switches draw a very small amount of current when switched off so you have to unplug the batteries if you do not intend to fly for a long time

To the original poster, I would really not worry about things such as double/redundant battery set-ups and fail safe switches if you are only at the stage that you are deciding whether to use 4.8V or 6V. There are some other things to remember if you go to 6V such as the fact that you will no longer be able to use your wall-wart charger and will have to buy a special charger that is capable of doing 6V batteries (If you continue to fly you will have to buy a proper charger eventually so this will not be a wasted purchase)

There is one other major area that I personally think that 6V has an advantage and that is with 2.4GHz equipment. It gives you extra head room before that dreaded brown out. Some manufactures might claim better resistance to brown outs than others, but it is better to be safe than sorry.

Hi Dick (CGRetired)

For these batteries on the receiver side you will have to use a regulator, available from the companies mentioned above, to bring the voltage down to 6V. For the transmitter a lot of people claim that the regulators (and say that they have used it successfully) in the transmitter are capable handling this higher voltage without the need for a extra regulators, but I know for a fact that JR have stated that using these 3S li-ion or li-po pacts would void your warranty, and I assume that the other manufactures would have the same policy.

If you are interested in this technology I would definitely recommend approaching somebody that flies giant scale aircraft as they normally make use of regulated li-ion dual battery set-ups. This and other forums have been great for me learn and ask questions, but I would defiantly not be able to even think of setting up a one of these systems in a giant scale aircraft with out the experience of the IMAC people that fly at my field.

Cheers
Pupmeister

CGRetired

My Feedback: (1)

Thanks, Pupmeister.

I don't intend to switch, I was just wondering about that voltage difference. The web site does not point that out, at least not that I saw, so I thought I would ask to see what answers I would get.

I thought it was that way (RX pack regulator requried) and also thought that the 11.1 volt LiPo 3S pack for a TX would not be very well accepted by the transmitter manufacturers. Also, consider the problems with LiPo packs and charging them in the radio, like most people would naturally do. Poof.. watch the smoke as your $400 radio set goes up in flames [:@]

I'll stick with what I have in the TX and stick with the 1200 Mah 6 volt NiMH packs in my aircraft.

Dick (CGr)

pupmeister

One other thing to add on the RX side, some of the new 2.4 GHz receivers (at least Spektrum and XPS that I know of) can easily accept this voltage unregulated, it is the servos that can not handle the higher voltage.

Cheers
Pupmeister

CGRetired

My Feedback: (1)

Ah.. ok. Good poop!!

Thanks again.

Dick.

RCKen

My Feedback: (9)

CGRetired,
I'm getting a chance to see the Duralite stuff for the first time. I just got some of their batteries to use in the two review B-25's that I'm doing. The batteries that I am using are Li-MN (Lithium Manganese) 2s2p packs. They are 7.4 volt and 4400 Mah packs. They plug into the regulator which brings them down to a proper voltage for the radio gear in the plane, they have regulators available in 5.1v, 5.3v, 5.6v, and 6 volt configurations. The regulator drops the power down to the usable voltage for the receivers. And it's the regulator that has the fail-safe switch on it. If the switch goes bad it fails in a power on state and will stay that way until the battery is disconnected. I'm pretty excited about getting to try these because of the power outputs available. Both of the B-25's are going to be power hungry birds (Hangar 9 B-25 has 8 digital servos and 3 analog, and the Top Flite B-25 has 13 analog servos), and when I was working with Duralite to get a system to work they estimate that I should get 10-20 flights off of a charge with this batteries!!! Trust me, I'm still chuckling about getting to fly that much without having to recharge!!!! The other REALLY nice thing is that with these batteries there isn't a fire risk like Li-po or Li-ion batteries. The Li-mn batteries can be charged right in the plane because there is no fire risk with them, which is really good because getting the battery packs back out for a charge every time!!!

Ken

bruce88123

Duralite offers seperate regulators, regulators with switches included and switches with built-in regulators. A wide variety of products.

CGRetired

My Feedback: (1)

Good stuff, Ken. I can't wait to read the reviews and see the videos. You ARE going to do video's, right?

Dick.

RCKen

My Feedback: (9)

Naw, I was thinking of just taking pictures of it and then making a "brrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr" sound with my lips!!!!!!!!!!!!!!!!


Ken

bruce88123

Again? Just don't do like the Falcon.[sm=47_47.gif]

RCKen

My Feedback: (9)

Trust me, I won't!!!!!!!


I doubt I'll be doing any low inverted passes in a B-25 anyway!!!!

Ken

David Bowes

Good comments. I've used 5V packs when the pack lead has been very long. I've done this for getting more tail weight(I tend to overpower a tad and invariably end up nose heavy).
No science here just more of a gut feeling about voltage drop over long leads??

jetmech05

Dave: welcome to the forums.
I see this is your first response. This thread is 9 years old.
I think the 4.8 versus 6 volt battery is a dead issue
Please don't stop responding. Just watch the dates

JohnBuckner

My Feedback: (1)

Welcome to the forum Dave and don,t worry about simply not noticing the date. I seriously doubt there is any here who have not done the same. Also it is certainly not a "dead issue". I still use 6 volt (five cell) Nimh packs in the vast majority of my aircraft and the are still readily avalible.

Just because one only does something a certain way does not mean there are many others out there who still may do something else. The question of 4.8 versus 6.0 volt is indeed a valid subject their are many out there still using 4.8 and worry about different battery chemistry as well a nominal voltages.

Dave your point about using heavier gage long leads on the pack where it is used for CG purposes is also and excellent point and I have done just that on quite a few airplanes.

I am asked all the time about this 4.8 v 6.0 question and most recently by a member that had move to Washington for ten years and had been an active warbird racer with us but on his move had hung up the racers and only flown sport planes. But now planning his return refurbished his racers and the local hobby shop sold him Life's. Now when he questioned me and I informed him first that he was going to have to buy a capable charger and even more importantly going to require two leads to the battery every time he charged this became a deal breaker and he bought new five cell Nimh instead.

John

ratshooter

Yes its an old thread but a good question. I only fly 72 Mhz radios and prefer Nicads. I have had to replace a few packs because all my radios are old but work just as good as the day they were bought. I have bought several nicad packs off ebay for decent prices and all have been good packs that hold their charge.