Silvanskii

My Feedback: (17)

'Lo. I am wondering how long my proposed setup will last, battery wise.

I'm looking at running 6 5995's, 4 8611's, and 1 5125 servo with one 4 cell 7.2V 3600 mAh Li-Ion pack. I've never used THIS many servos on one battery pack before. I'm curious to those that have more experience in this area, what run times will I be looking at while doing IMAC and 3D work with the setup? Rx incidentally will be a 950S.

I kind of hate to get another battery pack, but that thing from Smart-Fly, the BatShare looks pretty cool (and lightweight). Would it be worth it to grab one of these and add another 4 cell to the system?

flyinrazrback

My Feedback: (69)

I would run 2 packs, thats a lot of servos. Bat share not necessary, I like the idea of 2 switches, 2 regulators, and 2 batteries. What plane is it? The biggest plane I ran with one pack was a H9 Edge. I had 4 5945s in the wings, 2 for the ele, and 1 8611 for the rudder, and hitec 5925 on the throttle. I was using one 4800 4 cell TBM and a smart fly HD switch and regulator. I could get 7-8 flights on that setup. The 5955s draw some power, so thats why I would recommend a second pack at least.

famousdave

My Feedback: (61)

I would run two 4400 Mah packs (Fromeco, Duralite) on that setup, not only will you need the voltage, but you will also need the current of two packs. Anything less is just asking for trouble. If you are doing any 3D flight you will most likely go over the current delivery of one Li-Ion pack.


As far as backers, etc... they are fluff.. most of us use two packs, two 5A regs (like the SmartFly or Fromeco ones) and two good switches... run into two separate ports on the RX - its simple, provides full power redundancy and eliminates other stuff that can fail. We have been running this setup for years and it has proven over the long haul to perform better than most of the so-called "gadget" solutions.

I do have a powerbox on my big bird though..... did that just to clean up all the wiring, but it really was not needed....

DP

Hammbone

My Feedback: (309)

I agree with these guys. It's not the flight time that will be the problem, but the current flow. One lithium battery will not give you enough current flow to supply all those servos at once. Use two batteries and use good reg's and switches.

Jim

rcblimppro

This is one of those times where there are going to be just as many setups as there are guys. Most of what I have read here will work just fine but I'm still going to put a different spin on things. What you described is more servos than I run on my current 40% Extra so I am concluding that the power requirements are close to the same. Keep in mind that the Hitec servos go into a reboot mode if the voltage drops below the operating threshhold. This reboot takes as long as 3 seconds. So here goes, run two Froemco 4800 mah batteries through two JR charge switches into a Smart fly batt share ( To keep the batteries balanced ) into two Fromeco regulators that power a Smart Fly power expander. The power expander filters the power going into the RX and provides current to the servos. In a setup that does not use a power box and noise that is picked up by the servo leads goes directly into the RX. This setup would also be capable of delivering up to 20 amps peak. There are quite a few connections in the power setup so what I did was to break out the soldering iron and hardwire most of the connections.



Shawn

Silvanskii

My Feedback: (17)

That's kind of what I was worrying, the current draw. I'm nit-picking what all I want to put in my 3M 260 I'll be getting soon. I've never used any more than a 4 cel Li-Ion in all my 35% stuff, including my Carden 330, with 4 5945's, 1 5735, 2 8611's, 1 HS-60. It got a good number of flights in it. I never use regulators, don't need them. Haven't used them for 3 years in various 35%'s. (And incidentally, my 2.6 Yak has only two 7.2V 2 cell Li-Ions in it (ign., Rx.) and it can fly all day with ease).

Thanks for all the input guys, appreciate it! Not being an electronics guy, would adding regulators to this system really change the current draw (which seems to be the biggest issue as far as wiring and RX go)? In other words, even with two 7.2V battery packs, are regs needed as opposed to my single 7.2V I've been using with no reg?

flyinrazrback

My Feedback: (69)

Shawn, with the batshare, does the rx pull off both batteries at once, or just the one with more juice? I ask because if just one, you could exceed the necessary amps needed if pulling off one pack instead of the 2. My setup I prefer is the smart fly power expander, and their turbo regulator, one single failsafe switch, etc. Similar to the setup you mentioned, but one switch that is failsafe, and one regulator that will take everything you can get through it. Lots of options out there, but back to the original question asked I wouldnt use a single pack regardless on something like this.

Silvanskii

My Feedback: (17)

That's another thing that confused me to!

I brought up that BatShare thing because I couldn't tell if it utilized both packs or one or the other.

flyinrazrback

My Feedback: (69)

From Smart Fly's website

"The Smart-Fly BatShare continually monitors both battery packs and switches for the one with the higher voltage, and routes that to your Rx and servos. You may combine different size packs. In practice, with two good packs, the BatShare draws power equally from both packs, adding their individual capacities"

However, if you use smart flys power expander and turbo regulator, there is no need for the bat share. Both rx packs plug into the turbo regulator, and the on/off switch to the regulator is failsafe. If the regulator fails, it bypasses and direct to the rx, so very hard for that system to fail. It draws from both batteries at the same time, and equally shares the load.

Silvanskii

My Feedback: (17)

Just thought of something else. When I get the big one, I'm going to get rid of the "small" one.

This means I'll have another Rx.

Would it be feasible to put to Rx's in it, each with it's own battery (and each driving half the plane)?

Hammbone

My Feedback: (309)

Yes, That's what I do on 40%ers.
One 4800mah Fromeco battery, one smart fly mechanical switch, and one Fromeco regulator (with 3 output leads going to the RX) going to each RX which controls 1/2 the plane.
There's lots of ways to do it, but this is simple and provides the servos with the power they need.
I like the Fromeco regulator with the 3 outputs to the RX. Each standard type servo plug can only handle about 3 amps. By using 3 of them, you are now supplying up to 9 amps to each RX.

Jim

rcblimppro

The Bat Share does pull from one battery at a time but the switch back and forth is instantanious. On my setup I use Li-poly batteries because of the higher discharge rate. I aslo mentioned before that most of my setup is hardwired and the only connectors that are being used are Deans ulta plugs. The Bat Share supplys both regulators at all times and because of the high discharge rate of the batteries and all high amp rated connectors my system is still good for up to 20 amps. When the batteries are checked for voltage, they are always within .1 volt of eachother.





Shawn

RTK

My Feedback: (1)

I have always wanted to try that. I take it that you have had no problems with the RX? How many flights so far with this set-up?

Silvanskii

My Feedback: (17)

Heck, in my 35% Troy Built I flew that plane for a solid 3 years without a hitch. If I had to guess, I'd say it had well over... geeze I don't know, 600 flights? All doing heavy 3D/demo flying and learning. That one had a 2 cell Li-Ion (7.2V) in it, same as my Yak. Both the TBM and the Yak can easily last a days worth of flying. In fact, I've flown the Yak for two straight days, about 4 flights each (albeit keeping an eye on the V's with a meter with a load). The ignition batteries (2 cell Li-Ion) go just as long (probably longer).

I've flown my Yak and Extra (with 4 cell) without regs for this end of season. Probably 70 and 40 flights respectively.

My friend Darrinc has flown every plane he's ever had with Li-Ions in it without regs and that again numbers in the 3+ year range, his Hangar 9 Cap was at least 2 years old. He has Futaba, I have JR, never an issue. Another guy we know (former IMAC unlimited competitor) never ran regs in his 40% 3W Extra and his other planes for years as well, although I don't know his detials.

That's why I am leaning towards putting two Rx's in it, with 6 servos in one, and 5 in the other. A 4 cell pack to each Rx should be plenty since it cuts the number of servos down to what I am currently running (My Carden currently has 8, Yak has 6).

RTK

My Feedback: (1)

Thanx for the reply. I have a friend that did some work with Darrinc (and maybe you also) over seas and I was told he was running the straight Li-ion.

I would go with the set-up you just mentioned, but would Y each battery to each RX just for redundancy.

Silvanskii

My Feedback: (17)

Never thought about Y-ing them. Makes sense though. But again I question the fact that one battery (or switch) may fail leaving the system with just one battery, and then would that be enough to get you back to terra firma under control? I wonder if you would notice the dead battery immediately. I also wonder what the current draw would be in that situation.... Half and half?

Hmm...

RTK

My Feedback: (1)

You might not be able to tell if one failed, but check both side before each flight to be sure. According to most of what I have read there should not be a problem with current draw and both batteries should be "some what" equally drawn with no ill effect.