RCpropo

My Feedback: (1)

Buddy,
I am sure your problem is the NiMh batteries. These batteries have a high internal resistance which rises at the moment you increase the current demand; after the low voltage NiMh supply, the battery should recover by some minutes. I experienced this phenomena two times, battery were changed to LiIon plus good regulators and problems disappeared.
Do not use NiMh batteries with more than 4 high power digital servos or 8 Std. digital servos.

Best Regards,
Ricardo.

afterburner

My Feedback: (18)

Gotta disagree with Raf and Ricardo. You have to check the specs on the packs you are buying. For the price of a JR or Futaba labeled high capacity pack, you can buy a better quality, lower impedance Ni-mh pack and have change leftover. I have some Ni-Mh 4/5A size cells that can deliver 30 amps no problem. You are also putting these packs in parallel which double your capacity and halves your impedance. Why would they make car battery packs in Ni-Mh chemistry to run a big electric motor if they can't deliver the current ? The answer is they can. You just have to choose the right cells.

Marty

ravill

My Feedback: (11)

Marty,

You sound like someone who really knows about this stuff. I know its simple Ohms law but I really just want to plug and play, the fastest, safest way possible.

Raf

afterburner

My Feedback: (18)

Not an expert but I've been into electric stuff for about six years and before Li-Po's were really big, your only choices were Ni-Cd and Ni-Mh. I think one of the biggest advantages of Ni-Mh is they don't have the memory issues like Ni-Cd's. I understand the fastest and more importantly, safest way possible is usually most peoples goals. From my experience, when it comes to battery packs, the radio manufacturers leave a lot to be desired. Many other companies make much better packs using better cells and heavier gage wire. Many of the higher capacity NoBS battery packs have 18 gage wire to the connector. Not sure if I've seen that on a Futaba or JR battery pack. These companies will also make custom packs in whatever configuration you want. Just my two cents.

Marty

ravill

My Feedback: (11)

I buy batteries from NoBS/hangtime almost exclusively now.

Raf

1-large-bob

My Feedback: (18)

Hi Guys. Marty your right, they make nickel metals in diff. grades of cell. I called many batt. sellers today, and I learned a lot. SR batt. was very help full, His web site has a comparison of both batt. You can buy a nickel meta that will discharge at higher rate like the nicads. Im going to try two nicads SR 2200 5 cells. I hope this does the trick. I THINK IT WILL. I will report back. Thanks Robert

u2fast

My Feedback: (37)

robert, you coming to shreveport this weekend with your 18. sure would like to see her there, barry

1-large-bob

My Feedback: (18)

Berry. I have a big bird in Houston (fortbend rc) 3D event only. Im also having knee surgery on thrursday. Thanks for the invite, would love to go so I can learn some more.

garrett_mcdonal

Hey Guys,

I run GP3700 nimh cells in an F5b hotliner. These are supporting up around 130+amps and, if anything, the peformance gets stronger when you run them hard and get them nice and hot. These can be fast charged up around 8amps too and seem to last very well when subjected to this sort of treatment. I have run these cells as rx packs in jets without issues. The cells are quite expensive but if you solder up your own packs it works out okay.

Still, nicads can be handy when you need extra weight.

Regards,
Garrett

Doug Cronkhite

My Feedback: (34)

The receiver can handle most loads you can throw at it. A couple years ago when there was a lot of debate about running 1 vs 2 receivers in giant scale airplanes, there were some 'load to failure' tests done on the major brand receivers, and NONE of them would fail until you hit them with almost 30 amps.

The primary limiting factor in most airplanes is the power delivery. Your batteries have to be able to deliver good voltage even under stalled servo conditions.

One other note.. if you run a gyro in your airplane, this is extremely important, as gyros do not behave well in under-voltage situations.

1-large-bob

My Feedback: (18)

Well, changed my mine again going with two fromeco 5200 with two fromeco regulators. The sr2200 nicad are to heavy, they make a big diff. on the CG. I would have to make lot of changes. The regulators have two output leads per reg. total of 4. I only have two open slots on the rec., Can I put two leads on a y harnes. Fromeco web site say each lead (conector) is only good for 3 amps. I called them but got no responed. Will this work. Thanks Robert

bidrseed2

My Feedback: (2)

Never thought of this before, but as garrett says the performance gets better the hotter they get.

Maybe, ( And i have run Nimhs as power packs pre lipo days) the IR quoted is when the battery is hot, not fresh off the charger. That may explain some of the bad rep that nimh have as reciever packs, whereas as power packs, after a minute in the air, theyve warmed up nicely and performing as expected

as a reciever pack, it may take a long time to warm up sufficiently, if at all, to supply a reasonable voltage under load.

Ad Clark

My Feedback: (4)

Good morning Robert, I would run 1 lead from batt A reg. into an open port on the receiver. I would then connect the 2nd lead from batt A reg into the rx via a Y harness on your retract servo. I would then connect 1 lead from batt B reg directly into the reciever and likewise connect the 2nd Batt B reg lead into the rx via a Y harnes on the brake servo channel. I would not use ampflified Y harnesses. This will afford you the opportunity to introduce your power into the rx. with no less than 4 servo connectors. Remember that these connectors are only good for around 3.5 amps or so each. If you Y harness your regulator leads together first your are cheating yourself out of this advantage ( 4 multiple power inputs ) I can tell you that my testing has convinced me that multple input plugs make a huge improvement in keeping Mr. rx happy with lots of juice under heavy servo loads. Hope this info helps.

Ad Clark
BVM rep

rolsen12

Try looking into a battery power management devuce such as a Duralite Powerbox.
Elecrodynamics also has one.
They supply the receiver with it's own power and the servos with their own.

afterburner

My Feedback: (18)

I'm going to use two Fromeco regulators also with two outputs each on an F-15 that I can't seem to finish for some reason. I'm using a Smart-fly power expander which has two battery inputs. The Smart-Fly uses Deans connections which can handle much more current than the batteries or regulators could ever supply/handle. If you don't want to use some sort of power management system, then go with what Ad suggested. Use the two open channels on your Rx and Y the other two reg outputs to low current draw channels like brake and retract. Note that there are some things you need to be aware of when using dual regulators. Current draw will most likely be uneven betweeen the two battery packs unless the regulators are extrememly close in output voltage.

Marty

grbaker

My Feedback: (29)

Robert,

Sounds like you're headed in the right direction with your power setup. I would have never thought you could be low on power with your twin batteries. Guess we're all still learning.

One thing for sure.....you're not missing out on any good jet flying weather![:@]

1-large-bob

My Feedback: (18)

Your right Gary, were still leaning. Well i got my fromeco in the plane. Two 5200, two switches, two reg. with two out put leads each, total of four, going to four diff. RX ports, like AD CLARK, and MARTY sugested. Results are, me and my son can put a 6amp load on the rx system by putting pressure on the elevators an flaps, and we still have 6.0 volt. Alot better than 4.0 volt. Hey Guys thanks for the help. I learned a alot. Now I need to check my Big Birds. They also have JR nickel metals. THANKS ROBERT