TEBerg

My Feedback: (1)

Hey all. I have been looking at motor and battery combos to put into a 40-size biplane. I think that the E-Flite Power 46BL and 60 amp speed control will be a good power combo.

I have also been looking into Li-poly batteries and charging combinations. I would like to have two batteries and be able to field charge at the 2C or 3C rate. So, I'm currently looking at the Thunder power balancer/charger combo or the FMA Balance Pro setup.

I am currently stuck on a statement by E-Flite that indicates "You must however be sure that the battery chosen for power can adequetly supply the current requirements of the system for the required performance."

Well, I'm looking at the spec/setup page (http://www.horizonhobby.com/ProdInfo...structions.pdf) and agree that I will want about 600 watts of total power. Using a 4s Li-Poly battery would yield 13.2 volts and then dividing watts by volts would give me 45 Amps, this is right in the power band of the motor specs (between 40 Amps continuous and 55 Amps burst).....

So, I'm stuck on the SIZE of the recommended battery... Horizon says that using the biggest and most expensive is the best - Go Figure.. The 4S3P 6000 mAh battery which could yield 20 minute flight times.... Heck, I can't even afford the battery besides trying to charge that beast.. They also show using two 2S packs in series, but I don't think I want to charge two packs separately.. Doing that, I could skip the option to charge at 2C or 3C because it would take an hour to get both done..

***Now my question is: Can I run a straight 4S pack, Say 2000 mAh; or a 4S2P pack rated at 4000 mAh and get the same performance with reduced flight times???

I'm guessing that if the 'best' pack at 6000 mAh yields 15 -20 minutes of flight time, then a 2000 mAh pack would yield 5 - 7 minutes and a 4000 pack would yield 10 to 15 minutes..

What I'm woried about is the statement "Supply the current requirements".. If I use too small a pack (say 2000 mAh) would the battery just get smoked trying to deliver 45 Amps of power even for a short duration??

Thanks for any insight based on your experience.. Also, if you have used the E-flite Power 46, what setup were you running?? Weight of plane, performance, battery size??

jdetray

The crux of your post is what happens if you use a relatively low capacity pack, such as a 2000 mAh. The key here is the "C" rating of the battery.

To supply the required 45A:
A 2000 mAh pack would need a "C" rating of 22.5C (2A x 22.5 = 45A).
A 4000 mAh pack would need a "C" rating of 11.25C. (4A x 11.25 = 45A).
A 6000 mAh pack would need a "C" rating of 7.5C. (6A x 7.5 = 45A).

All of these packs would fly the plane, but as you've already figured out, the larger packs will give you more flight time.

If a pack can't provide the required current (because its "C" rating is too low), the pack voltage will tend to sag quite a bit under load. This may trigger the low voltage cutoff (LVC) of your speed controller, bringing a premature end to your flights. It doesn't do your battery pack any good, either.

So it's both the capacity of the pack (mAh) and the "C" rating that determines if the pack can successfully power the plane. In addition, it is usually a good idea to assume that battery packs may not deliver their full advertised "C" rating. Give yourself a bit of a margin.

- Jeff

ChopperMike

You can't charge a LiPo at anything over 1C unless you want it to explode!


I'm flying a Seagull Models Harrier 46 using an AXI 4120/18 and 7 emoli (Milwaukee V28 cordless drill packs). I've only had a few flights but it seems to be going well. This motor and battery combo with a MA 13-6 prop will give 700+ watts. I'm using a Castle Creation 45HV (high Voltage) ESC.


Mike

TEBerg

My Feedback: (1)

Jeff, Thank you very much for the great explanation.. I have been reading motor/battery information for several days trying to learn the different possible combinations. I had seen numerous references to 'C' ratings and did not know how to work with them.. Your explanation helps a lot and hopefully other members also.

Mike, your motor combo generating 700 watts sounds like it is a great setup. I have not seen any information on Emoli batteries.. Are they sold through RC sites or just cordless tools?

I have wondered about running a 'traditional' brushless setup, like your AXI 4120/18 with 13X6 prop and Castle Creations 45 speed control, but I have not looked into the size/winding/power for the different motors. I was leaning toward the Power 46BL just for simplicity. I would be interested if there were other motor/speed control combinations that would generate the 600 watts (or 700 in your example) that were either a lighter setup or would use less voltage/current to generate the same power output.

Also, I do want to confirm the statement about charging Li-Poly.. Thunder Power is setup with the 1010C charger and the 210 balancer which will charge TP packs at 2C and 3C. There is plenty of information on this in the RC Helicopter boards. I have seen the setup with the Szabo's and their buddy Rocky at the helicopter event here in Fresno California. 18 to 20 minutes to charge from 'low' to 90%+ capacity. Now, I understand that the last 10% is reported to take the rest of the hour to charge. That is explained in a couple of places on other boards. I have not seen the FMA balancer/charger work yet, but it is advertised with links on this board.

Thanks again. I'm off to practice and skydive at the Salinas Airshow this weekend. But, any additional information about possible setups will be helpfull. I need to get a budget going on this electric project.. That way I know how much money I have to hide from my wife...

proptop

My Feedback: (8)

You've already gotten some pretty good advice, so I'll just throw a few words in...

My 2 set-ups are similar...

1) Power 46 in a converted Great Planes PT-40 trainer (High School JROTC project ) that uses a Phx. 60 ESC and 4S1P Kokam 3200 Cellpro's...2, 2 cells in series, so I have 2 Cellpro 4S chargers to charge 'em both @ the same time. Typical flight times are short, about 5-6 min. and it takes about 45 min. to charge.
We are thinking about higher cap. batteries so we can fly longer...but the kids need to wash a lotta cars first to make the $$$

2) AXi 4120/14 in a H9 Pulse XT w/ Phx. 80 ESC and the same 4S1P Cellpro's and chargers...
The 4120/14 is very close in specs to the power 46, so the perf. parameters are virtually identical...

According to my Super Wattmeter, I get 55A. max. and just a frog hair under 700W. and both airplanes weigh about the same, or 5.5 lbs. ready to go...

Both are running 13 X 8E APC props...

They will get airborne (with a stiff breeze ) in about 30' and climb (true ) vertically for about 100 to 150' before leveling off.

ChopperMike

The maximum recommended charge rate for a Lithium Polymer battery is 1C. If the battery is very close to fully discharged it will typically take a little more than an hour to charge. This is because the charge current is either reduced or pulsed toward the end of the charge cycle. A charge current higher than 1C risks cell voltage going over 4.2V. There is 1 battery that I know of that can handle higher current. The A123 cells can be charged at up to 3C. I've heard of some charging the emoli cells at higher currents but it is not recommended.

The only way currently to get the emoli cells is to buy a Milwaukee V28 pack and disassemble it which will yield 7 cells. I recently bought 2 of the packs off Ebay for $188 shipped.


Mike

proptop

My Feedback: (8)

That's correct, typically, you don't charge a Li-Po at over 1C...but you don't want to fully dis-charge them either, so if you leave some in them, it won't take an hour to re-charge them.

FMA Balance Pro packs are supposed to be able to take up to a 3C charge rate...

jdetray

[link=http://www.bigerc.com/]Big E-RC[/link] sells ready-made emoli packs in configurations from 2S to 7S.

- Jeff

Flypaper 2

I'm using the drill pack li-ion from the Makita drills. Stripped down they give 18.5 volts 5 cell 3000 MA on a Himax 50 motor running a 13-6 prop. Run time is 10 mins of mixed throttle. 1/2 hr. charge time on the FMA Balance pro charging at 2 C with no problems. Plane is the Hangar Nine Pulse XT. Very happy with the whole system.

proptop

My Feedback: (8)

Gord...that sounds interesting...how much does the pack weigh?

Flypaper 2

Stripped down, weighs 1 LB. even. Probably heavier than an equal lipo but the cost and safety justifies it in my book.

proptop

My Feedback: (8)

Not much! My Kokam 4 cell pack (3200 mah ) weighs 14 oz.

That 18.5 V. that's fully charged...no load right?
That would be almost = to a 5 cell li-po
My 4 cell = 16.9 right off the charger...

bfreee

You are on the right track. dont go below 3000, though. I found that you are much better to go one or 2 cells more & come down one or 2k on mah. The extra voltage cuts down on amps (see ohms law) so you will give you speed control a break & have awesome power. Just use the watt formula that you see around, for good 3d you really need 200 per pound or more for awesome pull out. if you are just tooling around, half that is okay.

Flypaper 2

LI-ion 18.5 V shows 20 V off the charger.

stinky

I am flying a Nexstar 7lbs 4 oz with a E flite 46 I am using a Thunder Power 8000 mah 4s4p 14.8v and get 51 amps 742 watts spinning a 13-8E APC prop flight times are 25 minutes depending on the wind hence throttle settings. I can fly at about 60% throttle. I will always throw this in I have tryed other brands of batteries and still haven't seen any produce the power that Thunder Power provides. I will pay more every time!
steve

TEBerg

My Feedback: (1)

Thanks for all the replies.. This helps a lot.. I'm probably leaning towards approx 4000 mAh packs that will handle 15C loads.. That puts me running about $200 for each battery, $200 for the charger and $100 for the balancer.. That's keeping it all Thunder Power brand for the fast charging.. Then I need the motor, speed control and charging station (probably a deep cycle battery and float charger). Wow, It's time to start saving up!!!!

Thanks again for all the feedback..

I'm gonna keep 'tweaking' my motor/battery options as I get into the project. Which, by the way, is going to be a Pica Shu Fly Bipe. Or, at least that is my current plan.. Then, if something happens to the Bipe, I should be able to drop the power combo into the World Models P-51 very easy..

gooseF22

Hey guys let me throw something out I just did with the help of Dave Thacker of Radical RC.

I have a knockoff which specs out identical to the E46 at 670KV and 55 amp max. We put a Castle phoenix 60 on it, but used castle link to set the cut at 18.2 volts, just barely above 3.0/cell. So I am getting 24 volts. I started with a 12-6 apc, and it tachs at 10,000 rpm and 800 watts pulling 44 amps. It pulls a World Frontier Senior, (just like a Sig Senior), correction, it rips that model off the ground. It has to be close to 1 to 1 thrust. I have it on 4 2000 kokams, in a 6S2P 4000 config. It flies at 1/3 to 1/2 throttle for 20 min, and wll do go arounds at 1/2 throttle too. I am going to amp a 12-8 and a 13-6 and a 13-8 to see if I can keep them under 55 amps, but we have to be getting close to 100oz of thrust with a 12-6E APC.

THe trick was using castle link because the beep in settings on the ESC went up to only 4s. The other cool thing is that since I have 4 3S 2000 packs, I can use them in almost every other model I have like my typhoon, slow stick, park flyer, glider......

FentonFlyer

My Feedback: (11)

I use the E-Flight 46 in a 6.5 lb Excelleron 50 pattern plane. On 5s2p(2-3s2100and 2-2s2100),I'm pulling about 50 amps static with a 12x8 APC-E for about 900 watts in. This setup provides excellent speed and unlimited vert and flight times of around 7 minutes of agressive aerobatics uses about 28 to 2900mah.

91zulu

My Feedback: (2)

Here is some options on motors that are a bit cheaper that the Axi and other top names...


http://www.rchotdeals.com/Products/r...otor_home.html

For your set up you could use the A4130-8 and yes I know the price looks cheap but they are good motors. Remember sometimes you are just paying extra for a well known name.
and yes I use these motors.. I also have the Himax HC5030.. which is the same as the A4130.
Paid $134 for the Himax $55 for the 4130. Both motors are 60 size.