ARF SV-11. What battery?

[Paul Taylor]

What size battery is needed to haul a ARF SV-11?

I tried a Thunderpower 5s 2800. It ate it all but 1%. 😝

[Ken Culbertson]

What size battery is needed to haul a ARF SV-11?

I tried a Thunderpower 5s 2800. It ate it all but 1%. 😝

My plane is just a tad larger than an SV-11 (710sq, 70oz) and I use a 6s 2800 Li-Ion.  It uses all but 3% but that is normal for Li-Ion.  Guess weight is an issue.  I have another plane that is right at 700sq and 65 or so ounces.  It uses your battery TP 2800 5s and lands at about 15-20%.  Just when you think you have it all figured out - you don't.

Curious - what motor?  I am running the BadAdd 3515 and 3520. When I switched to the 3520 my battery usage went DOWN.  When I switched from a MAS 3 blade 11-6 to a BadAss 12-5 my usage went way down, about 300mah, but I didn't like the way it cornered so I went back to the three blade.  I have borrowed one of Igor's props and tried it.  Usage was way less with better corners but alas, I had to give it back!

Ken

[Brent Williams]

As Ken mentioned, the prop you intend to use makes a huge difference on amp draw. 
If you are handy with an iron, make up your own 6s/2800 Li-ion packs that weigh just slightly more than 5s/2800 ThunderPower Lipo packs.
You could also make up 5s/4500 Li-ion packs that weigh about the same as a ThunderPower 6s/2800 lipo.

The Molicel P28A, P28b, and P45B cells are on sale right now.
https://www.18650batterystore.com/products/molicel-p28a
https://www.18650batterystore.com/products/epoch-18650-2800mah-40a-battery-p28b
https://www.18650batterystore.com/products/molicel-p45b

[Paul Taylor]

Maybe a little more information might help shed a little more light on the subject.

It has a E-Flite Power 32 770Kv motor
Castle Ice 50 ESC and a FM-9 timer.

The E-Flite website says that the 770kv is equivalent to a 30-36 size glow. Could it be it needs more current draw to turn a 12 inch prop?

[William DeMauro]

Brent is right on with the LION suggestion But I would stay with the Epoch 2800 and make a 6 cell or make a 5 cell using the molicel p-45b. I would not bother with the p28a as long as the others are available. If you just want an off the shelf battery get the Thunderpower 6s 2800 which is on sale for another day or two for 35% off. Your motor should be fine. Many of us are using the Badass 3515-710 in those sized planes incase you want an alternate motor. If you go to a LION pack be sure to reset your Low Voltage Cutoff to 2.5-2.6 volts as they run on a slightly different discharge curve.

[William DeMauro]

Maybe a little more information might help shed a little more light on the subject.

It has a E-Flite Power 32 770Kv motor
Castle Ice 50 ESC and a FM-9 timer.

The E-Flite website says that the 770kv is equivalent to a 30-36 size glow. Could it be it needs more current draw to turn a 12 inch prop?

The 5 2800 cell is just not enough battery for that plane. I've had a few SV's and am very familiar with planes in that size range. The 12" prop is fine. Igors prop is way better like Ken says. And the Badass 12" props 12x5 or 12x6 should also work very well. Add a cell or up the capacity. Both solutions will work.

[Paul Taylor]

Thanks Guys!!!

I am not going to attempt making batteries. So off the shelf is where I’m headed.

[Ken Culbertson]

Maybe a little more information might help shed a little more light on the subject.

It has a E-Flite Power 32 770Kv motor
Castle Ice 50 ESC and a FM-9 timer.

The E-Flite website says that the 770kv is equivalent to a 30-36 size glow. Could it be it needs more current draw to turn a 12 inch prop?

Have you run that motor yet?  The specs say that it is only rated for a 4s battery.  That is only going to give you about 15v to play with.  I could be wrong, I am not familiar with the E-Flight motors other than what it says in the specs.  The SV-11 is a pretty big dude, you might need more juice.  I ran your timer and ESC with 4s batteries on my Twister using a Cobra 2820/12.  That is a .46 equivalent.  The 2826 on a 5s is a .60 equivalent.  Quite honestly if I were outfitting an SV-11 I would use one of these 4 motors:
BadAss 2826-820
BadAss 3515-710
Cobra 3515/14
Cobra 2826/10

On a 5s battery all of these will give you a .60 or better equivalent and all of them will handle a 12" prop without a problem.

One of the problems with electrics is that the ESC and Timer conspire to give you the RPM's you ask for or melt the motor trying.

Hopefully someone really familiar with the E-Flight Power 32 will jump in and either confirm what I am recommending or explain why I am full of **it!  Could go either way - 


Ken

[Dan McEntee]

  I would just a 1.5 Volt Ever-Ready ignition battery to the glow plug installed in a ST.G-51 or ST.60!  That would be the only battery you would ever need!! 
  I hope you all had a GREAT THANKSGIVING!!!
  Type at you later,
    Dan McEntee

[Neil Rogers]

Here's my SV-11 ARF setup:
E-Flite Power 32
Castle Creations Ice Lite 60 (I think)
Hubin Timer
Thunder Power 5S 2800
APC 13 x 4.5 EP
63 ft (eyelet to eyelet) .018 lines
5.25 second lap time
5 minute 15 second run time

There is no room to add extra laps between tricks, which you shouldn't do anyway, and I get 4-5 laps at the end of a flight and 28-30% battery left after a flight.

This setup came about through discussion with Chris Cox and Paul Walker when I first switched to electric.

I fly (low) expert level and I am very happy with the results I get with the above.

[Ken Culbertson]

Niel - I have a strong likelihood to trust advice from those two.  The power 32 is only rated up to 16 volts which is over a 4s but under a 5s.  I have always been told that when a motor is not rated for a higher cell count you shouldn't go there, it could overheat the motor.  I will have to confess to having used a 5s on a Cobra 2820/12 without damage but she sure did get hot.  Is it possible that we are simply taking advantage of the fact that we do not push these motors like an RC plane would and we are within the "actual" voltage range vs the published one?  Having said that, I still would put a larger motor into an SV-11.

Ken

[Paul Taylor]

  I would just a 1.5 Volt Ever-Ready ignition battery to the glow plug installed in a ST.G-51 or ST.60!  That would be the only battery you would ever need!! 
  I hope you all had a GREAT THANKSGIVING!!!
  Type at you later,
    Dan McEntee

🤣😂🤣😂🤣😂

[Leonard Bourel]

I am with Dan but he beat me to it 

[Frank Imbriaco]

 About 8 years ago, I had one and flew it often. Initially it had a Power 25 with a 4S 3900mAh then switched to a Power 32 and ran a 5S 3400mAh which was fantastic and left me with about 20% after landing. That was before active timers .

[Neil Rogers]

Hello Ken,

Interestingly, the Horizon Hobby website does give a voltage rating of 12-16.8 volts, however it also shows this information:

Needed To Complete
- 60A brushless ESC
- 3–5S Li-Po or 10- to 16-cell Ni-MH/Ni-Cd
- 11x7 to 14x10 prop; 10x10E tested on 5S in Sundowner 36

The setup I use is the same as Chris used before he upgraded to the Igor system.  I haven't had any issues in the three years that I've used it.  It's as simple as plug in a battery and fly.  Rinse and repeat.

I think you might be on to something when you said that we don't push our equipment like the RC guys do.

[Mike Alimov]

Paul, in my personal experience a TP 5S 2800 battery is quite sufficient for the SV-11 ARF, if:
The plane is at the typical 64-65 oz total weight;
Lines are no longer than 63' eye-eye
Lap times are around 5.2"-5.3"
Prop is a decent 12-6
Total run time is 5'20" or less
RPM in the 8300-8500 range
Wheelpants and spinner installed (related to air drag)

My boys qualified for the Nats Top 20 a few years ago flying this exact setup. Nothing was overheating, and the remaining battery charge was around 20%.

If you exceed any of the above parameters, then yes the battery consumption will go up, sometimes quite dramatically.

[Paul Taylor]

Paul, in my personal experience a TP 5S 2800 battery is quite sufficient for the SV-11 ARF, if:
The plane is at the typical 64-65 oz total weight;
Lines are no longer than 63' eye-eye
Lap times are around 5.2"-5.3"
Prop is a decent 12-6
Total run time is 5'20" or less
RPM in the 8300-8500 range
Wheelpants and spinner installed (related to air drag)

My boys qualified for the Nats Top 20 a few years ago flying this exact setup. Nothing was overheating, and the remaining battery charge was around 20%.

If you exceed any of the above parameters, then yes the battery consumption will go up, sometimes quite dramatically.

What motor and ESC?
I have gotten some feed back that not all motors consume power the same.
I’m of the opinion “your mileage may vary”.

This SV ate a TP5s 2800. 😎

[Brent Williams]

Paul, can you fill in a few of the missing bits of info of your current SV11 combo?

Weight with battery installed.
Line length total, (handle to center of plane.)
Prop brand and size.
Run time.
Rpm.
Lap time.

[Paul Taylor]

Paul, can you fill in a few of the missing bits of info of your current SV11 combo?

Weight with battery installed.
Line length total, (handle to center of plane.)
Prop brand and size.
Run time.
Rpm.
Lap time.

Hey Brent,
I can only give to guessments. We only put two flights on it. This was a hand me down plane. And my scale stops reading at 55oz.

Weight with battery installed. Again a SWAG - Looking at ~66oz with battery. According to the website the 5s is 10oz.
Line length total, (handle to center of plane.) 66' 7''
Prop brand and size. APC 12x6e
Run time. 5:30
Rpm. Program box shows 10,134. I did not put a tach on it.
Lap time. Did not get a lap time but is seemed around 5.x

I wish I could get you exact numbers but I was on two borrowed batteries. After the first flight it almost seemed like the motor did a low voltage shut off. We pulled the battery and it was showing 1%. After the battery cooled off it rebounded back up to 14%. The second flight we dialed the time back to 3 minutes just to get a feel of the plane and did not want to stress test another battery that did not belong to me.

Another side note. We know the person that had this plane before was flying on 4s batteries but no one remembers mha. We do know that the batteries did looked like sausages and were all puffed up.

I have ordered some TP6s 2800 batteries. I know they are 2oz heaver then a 5s but was pulling my hair out trying to get the right battery.

[Ken Culbertson]

Prop brand and size. APC 12x6e
Run time. 5:30
Rpm. Program box shows 10,134. I did not put a tach on it.
Lap time. Did not get a lap time but is seemed around 5.x

Good move to go to the 6s assuming the motor can handle that much voltage.  That is a lot of RPM's on a large high pitch prop.  Gotta have a tired battery after a pattern of that.  That recovery is indication of a cut off.  Mine usually only recover 2-3% when they cool but then Li-ion handles the extremes better.  I have never had good battery results with a 5s on props over 12-5.

I know changing out batteries is not a buy one and you are done.  To have any sort of session or contest you need about 6 or a field charger.  That is like $500 in the 6s column.  Just to keep poking the bear, a BadAss 3515-710 would haul that plane around just fine on a 5s and not cook either the battery or motor.  One of the other issues is the FM-9 timer.  You have to set your RPM for the worst case scenario.  With an active timer you can set your base RPM's much lower and rely on the boost for the high demand.  I am running about 8500 rpm on a 65oz plane about the same size using a 5s battery and an 11-6 three blade or a 12-5 two blade.  I have been running the current set of 4 for two years and just over 50 cycles @ with no puffing.

Ken

[Paul Taylor]

Good move to go to the 6s assuming the motor can handle that much voltage.  That is a lot of RPM's on a large high pitch prop.  Gotta have a tired battery after a pattern of that.  That recovery is indication of a cut off.  Mine usually only recover 2-3% when they cool but then Li-ion handles the extremes better.  I have never had good battery results with a 5s on props over 12-5.

I know changing out batteries is not a buy one and you are done.  To have any sort of session or contest you need about 6 or a field charger.  That is like $500 in the 6s column.  Just to keep poking the bear, a BadAss 3515-710 would haul that plane around just fine on a 5s and not cook either the battery or motor.  One of the other issues is the FM-9 timer.  You have to set your RPM for the worst case scenario.  With an active timer you can set your base RPM's much lower and rely on the boost for the high demand.  I am running about 8500 rpm on a 65oz plane about the same size using a 5s battery and an 11-6 three blade or a 12-5 two blade.  I have been running the current set of 4 for two years and just over 50 cycles @ with no puffing.

Ken

Good info Ken. I might have to put my Circuit flyer timer in this monster. We have charging stations at the field so I can recharge. I might return the 6s batteries eat the shipping and looks for something else. 🫤

[William DeMauro]

Keep the 6s. In the end you will be glad you did. You won't be running the batteries to the limit or stressing them. You will have plenty of overhead at the end of the flight. Can you use a 5s? Yes. You will be at the very limits every time. No room for error and as soon as the battery tires a little its done for you. That motor will handle 700watts. It will handle the 6 cell as long as you do not exceed 700 watts for any length of time. You won't ever even get close to it with that plane. I've bench tested enough batteries (over 100) to know that we use 110watts per pound on average, plus or minus 10 to fly our planes. Those numbers are pretty constant. A 4 pound plane in the worst case is using 450-475 watts to fly it. Ideally I would prefer a bit lower kv motor but that E-flite motor will work fine. Add a cell. Go fly your plane.

[Ken Culbertson]

William is right.  I did not know you already had the batteries paid for.  A bigger battery is always better.  His formula does not consider drag but unless you have added lots of drag inducers like elevator fences (I use them), rudder offset, vortex generators, leadouts way back, canards (a huge drag but worth it), etc. the SV-11 is pretty clean.

I had no idea that the specifications for the Power 32 were so misleading until this thread.  Thanks!  Looks like they are intended to get you to buy the 46.

Judging from what my flying buddies experience using the 6s on their light slippery planes they consume somewhere around 18-1900mah on a typical day. Less if a strong wind or cool temperature, and more if it is hot or calm air.  At the same session, I will consume between 23-2600mah with my heavy draggy plane.  We all use BadAss 3515-710 or 3520-650 motors with 2800mah 6s Li-Ion batteries.  The 3520 is a battery hog compared to the 3515 but the batteries, they just don't seem to care as long as you don't hit 100%.   

ken

[pmackenzie]

If I read it correctly, the guy you got the plane from was running 4S.
5S might also have been simply too much voltage for the 4S motor/prop combination.

If you use the same motor and switch to 6S, things will not end well. You need the correct motor to run that much more voltage.


You need to give more details about the motor, lots of guys on here can give you advice, but not without some details of the equipment.

[Ken Culbertson]

You need to give more details about the motor, lots of guys on here can give you advice, but not without some details of the equipment.

He told us earlier that it is an E-Flight Power 32 which is only rated to 16 volts.  It is a 35mm motor which should be good for a 5s.  Personally, I think that the manufacturer rated it at 16 for a reason but several here are using it at 5s and maybe even 6s. Horizon's specifications are conflicting.  They specify that it is up to a 5s in one paragraph and a max voltage of 16 in another.  If I were buying new, I would go with a BadAss or Cobra at the same price but if he already has one then I would probably try the 5s.  Somewhere out there is a prop that will most likely make the ESC and the motor happy but WATCH THE HEAT on the first flights.  Remember, the motor has no say in the RPM's it is asked to deliver, it's "Do or Die".

Ken

[Bill Schluckbier]

Hello,

I have been reading this thread with interest. I have been flying electric since 2005 for R/C and since 2020 since I got back into C/L.  Take my suggestions with a grain of salt, but here it goes:

1) Be careful if you are using one of the small, hand held voltage checkers which will report out battery usage based on voltage; they are not very accurate.  If you take the measurement immediately after a flight it will give you a different result than if you wait for 5 minutes and allow the battery cool.  After a flight, the battery will be at its lowest voltage which will recover somewhat as it cools.  The only way to accurately know how much was used is to charge the battery.  As batteries age they loose capacity and the ability to hold voltage under load, as a result, given identical flying conditions, the usage will go up over time (the ESC will use current to make up for the lower voltage in order to make RPM).  It is a good idea to track this over time.

2)  5S on a 770Kv motor is probably doable, although the Kv is probably a little on the high side.  At nominal voltage (3.7 volts/cell) the motor can spin up to 14K RPM.  If using a 12x6 you will be looking at setting the ESC to provide between 9200-9600 RPM; the motor can easily do it but it may not be at its more efficient point.

3)  Test different props; they are not all equal even if the numbers might be the "same".  If you are using an APC, maybe try a Xoar or Badass prop or a CF prop (if you do not mind spending the money).  You will have to adjust the RPM to get the lap times that you are used to because the props will behave differently.  For economy in level flight for a given speed, a higher pitched prop spinning at lower RPM will be more efficient.  If you are using a 12x6 it might be worthwhile to try out a 12x7 or 12x8. The motor is large enough that it should be able to handle the extra pitch and still respond to the ESC inputs.  Also, since the set-up is capable of 14K RPM trying out a lower pitch prop might be interesting; this is more related to the ESC set-up (the commutation frequency).

4)  If the ESC is programable, maybe looking at different commutation frequencies might help.  There is a tradeoff between the ESC running hot or the motor. 

5)  Shorten your flight time by a minute so that you do not run out of battery while testing.  Take a test flight with the current set-up so that you can establish a reference with respect to consumption for the shorter flight.  That way you will have a benchmark to compare against as you experiment. 

Have fun.

[Ken Culbertson]

For economy in level flight for a given speed, a higher pitched prop spinning at lower RPM will be more efficient.

Bill, this is something that I have not heard before - a higher pitch past 6.  I think a lot of our, including my, mindset is still in the hard learned lessons from IC where RPM on the ground where we measured it was at best a sophisticated guess for what it would be in the air.  Now we tell it.  With an active timer you can control the boost and to some degree the brake during maneuvers so this leads to the proposition that the pitch of the prop is less important to the flying of the plane but very important to battery usage.  My current design is extremely high drag and uses most of the capacity of the battery in a pattern. (2400-2600mah on a 6s 2800 Li_Ion which if full bore battery abuse).  I am running somewhere around 9000 rpm on a three blade 11-6 prop or a 12-5 two blade.  Correct me if I am wrong but what you are saying is that since nearly 2/3 of the pattern is spent in level flight it might be more efficient to drop the RPM's to say 8500 and go to a 7 or 8 pitch and adjust the boost? 

Has anybody tried this?  I am getting so little handle time now that experiments are difficult to schedule!   

Ken

FYI my motor in this plane is a BadAss 3520-650

[Bill Schluckbier]

Hello Ken,

From my R/C flying, generally speaking, in cruising flight, a highly pitched large diameter prop will be more efficient than a smaller diameter prop of lower pitch spinning at higher RPM (take a look at indoor FF models, they turn huge props at very low RPM). My first electric C/L (a converted SIG Fazer built from the kit for C/L) initially flew on a 13x10 APC prop using a Hacker A30-10 on 4S.  I did not realize it at the time, but that prop was a huge ask of that motor.  I believe that my static power ran at about 350 watts for a model which weighed 54 oz, not overpowered at all.  The static current was in the 23.5-24.5 amp range. The RPM on that set-up was in the 5800K range give or take a couple of 100's.  I basically assumed that what I had learned from the R/C side of things carried over.  The plane was slowish with a 5.4-5.5 lap time but it could fly the whole sequence.  There were spots at which the line tension was minimal but somehow it made it through.  What I did not know at the time was that the RPM was too low for the ESC to govern properly.   That set-up was the lowest powered set-up I used on that model.  Eventually, I settled on 6S using a motor with a 510 KV turning a 13x5 prop.  With the new set-up, the base power is in the 450 watt range (static).  In flight, while maneuvering, I will see the power increase by about 30-40% while the ESC tries to maintain the RPM.  That flies the model nicely.

If you are not using an active timer, but just the ESC in governor mode, the higher pitched prop will give you more wind up in windy conditions, for that reason most of my current set-ups use relatively low pitch props (say 4 or 5).  At any rate, if he wants to use what he already has I think that testing props to see if you find one that works best makes sense.  If not, I would probably go to a lower Kv motor (say a Badass with a 710Kv) and maybe try a 13" prop. Larger props overcome drag more effectively than smaller props and the SV-11 is not a small model.

Half the fun of the hobby is experimenting and playing with things; I am certain that there are others who a better versed on this than I am.  I am just stating my experience.

Bill