I'm working on a project that involves a Hifionrc F7 25A, that will be feeding 1103 7000kv motors. I know the motors are for sure good for 2S, and I've even heard 3S. Obviously the motors are the weak link, but, how hard could I push them? Would a small 4S be out of the question?

Is there a link that could help? I've looked at Ecalc, but honestly don't know how to use it correctly

Thanks!

Without knowing the brand and model of your motor, it is hard to tell you. Generally, motor with this spec can handle 3S. Some can even handle 4S, but not all of them. If you want to use 4S, either try to find spec sheet for your motor. Or try 4S and risk burning them.

(08-Apr-2021, 04:11 PM)voodoo614 Wrote: Without knowing the brand and model of your motor, it is hard to tell you. Generally, motor with this spec can handle 3S. Some can even handle 4S, but not all of them. If you want to use 4S, either try to find spec sheet for your motor. Or try 4S and risk burning them.

Thanks for the reply. I guess I should have mentioned that. They are Emax 1103, 7000kv, the stock TinyHawk 2 Freestyle motors.

I know these are oddball, propriatory size. I'd like to see how they work before I attempt to adapt a different brand or size of motor to the frame. I am open to suggestions...

Yes, this build is on a TinyHawk 2 Freestyle, I will be doing a build thread about it here soon enough, I'm hoping. I'm taking notes and pictures along the way, and I will post everything when it's done. This is basically my first build, I don't want to drag it out by doing a play by play 'live' thread.

It should be a beast!

Emax does not have any spec for this motor. you probably have to email them. They will likely tell you only 2S.

The only spec that I could find on the EMAX 1103 7000 motors is 2S.

Also, keep in mind, the cell count (S) determines the voltage; for any given cell count, they all have the same voltage {HV aside}. All 2S have the same voltage, all 3S have the same voltage, all 4S have the same voltage. The small or large only refers to the mAh or how long it will last; larger = more time.

(08-Apr-2021, 10:11 PM)iFly4rotors Wrote: The only spec that I could find on the EMAX 1103 7000 motors is 2S.

Also, keep in mind, the cell count (S) determines the voltage; for any given cell count, they all have the same voltage {HV aside}. All 2S have the same voltage, all 3S have the same voltage, all 4S have the same voltage. The small or large only refers to the mAh or how long it will last; larger = more time.

Yea, I can't find much else on the specs either. I met someone on a FB group, that does 3S on a TH2F, all he did was a larger capacitor. He claims he's been flying it like that for over a year. I'm not quite sure why he would BS me. I'm just taking his word for it, and I've seen vids of it, so, that's proof enough for me.

Thanks for the rundown on the voltage vs mAh. I kinda sorta knew that, and in saying 'small' 4S, I guess I meant more like, lighter weight. Is it's safe to figure that the lower the mAh, the less heavy it is, on...average?

Not always, I know. I'm my case, my 2S RDQ 525mAh are considerably smaller and lighter than my 2S CNHL 450mAh.

Thanks again!

(08-Apr-2021, 10:48 PM)JSchubz Wrote: Yea, I can't find much else on the specs either. I met someone on a FB group, that does 3S on a TH2F, all he did was a larger capacitor. He claims he's been flying it like that for over a year. I'm not quite sure why he would BS me. I'm just taking his word for it, and I've seen vids of it, so, that's proof enough for me.

Thanks for the rundown on the voltage vs mAh. I kinda sorta knew that, and in saying 'small' 4S, I guess I meant more like, lighter weight. Is it's safe to figure that the lower the mAh, the less heavy it is, on...average?

Not always, I know. I'm my case, my 2S RDQ 525mAh are considerably smaller and lighter than my 2S CNHL 450mAh.

Thanks again!

It also depends on the props you're running, you might get away with a 4S if you run a very shallow pitch. But since the props are quite small I don't know if the pitch will make as much difference as something like a 5 inch.

Hi JSchubz,

Since most 1103 7000 motors are rated 2s-3s, you would think that these would be, too...and they might be...or not...who knows for sure. Since the FC will handle up to 4s, you could try a 3s...maybe the motors will be ok...maybe they won't. At this point, everything is speculation regarding  those motors. Once you have it together, fly it with 2S. If you feel brave, you could try a 3S....I would stay close just in case you cook a motor. 

I would also suggest a pretty decent capacitor {like the guy you quote as running 3S}, I would probably use my standard 1000 uf 35V.

My all stock GEPRC Phantom has 1103 8000 motors and handles 3S just fine. I often fly it with a GNB 3S 1100 mAh battery {and get about 17 minutes of fly time}.

Again, in theory, so should the EMAX 1103 7000 motors. If I was going to try a 3S battery, I would probably try a GNB 3S 650 mAh {Yeah, I just happen to have those} first and see how it does...No punch outs though. If that worked and I didn't blow a motor, I might go for the 1100 mAh. Again, the voltage is the same for both 3S batteries.

None of the 1103 motors that I have found are rated more than 3S...so that would likely be the max.

Battery weight is interesting. You would think that a particular specification (cells and mAh) would all weigh the same, but they don't. Generally, bigger is heavier. Here is a comparison for you... a GNB 3S 1100 mAh battery weighs about 67 grams, which is pretty close to most 4S 650 mAh batteries. On the flip side, some 3S 850 batteries weigh about 80 grams. You really just have to look at the specifications for the batteries you are interested in and compare them. Moving up in mAh adds weight, moving up in cell count adds weight. Some say that it has to do with the "C" rating...or the "quality".

I had planned to use the stock TH2F Avon Rush props, and honestly hadn't even thought of changing them. Again, I don't know much of anything about props, but as I recall (have read) this is a relatively 'aggressive' prop. I think I have seen some use a bi-blade prop on the TH2F, but more for an endurance, or long range setup. I know it's a T mount, but not aware of different brands and types that will fit. Wild guess, but is that a 1.5mm shaft on the Emax? If so, will any 1.5mm, 2.5" prop...fit? I know a 3" won't, at least not on -this- frame.

I got a 470uf, 35v Panasonic cap, as heard that is a highly rated brand. The 470uf was recommended by a good friend of mine, but now you say I should use a 1000uf instead? (Lol) There was, I believe, a Sanyo, same specs, included with the Hifionrc. It is considerably smaller, but I'm going with the Panasonic.

I finally got, a pair of each, a 3S 1100mAh (HV, 50C) and 4S 650mAh (HV, 60C) lipo in my hand, both RDQ. Previously, I had only seen them in online pics and YouTube vids lol. They are both smaller than I had thought!

The 1100mAh 3S seems pretty large in size. I would be curious to see the weight differences between a 'small' mAh, and 'large' one, of the same brand. My mind tells me a smaller capacity lipo -has- to be lighter, but it also tells me a lot of other things, we argue all the time!

I see the WH numbers now, that I'm pretty confident that is watt hours. An endurance rating of sort I'd guess, but I won't ask about that now...I ramble too much as it is

Thanks all!

Jeff

Hi JSchubz,

For the original specifications of 1103 motors which we don't really know the rating, but know the specs are 2S a 470 uf capacitor would be fine. No problem. 

Now, the new and marginal specifications of running a 3S or higher battery changes things a bit. Will the 470 uf capacitor be enough, well...maybe...and maybe not.  Keeping in mind that we don't know the rating of the motors, so anything over 2S has the potential to fry them, therefore, a larger capacitor might, or might not, help. The larger capacitor WILL absorb more energy.  

It is not so much that the answer is different, but rather that the criteria has changed which could marginalize the motors.

I use 470 uf only on 2S quads or for a specialized quad. I use 1000 uf on my builds intended for 3S or larger batteries.

How big of a fire extinguisher you need depends on the size of the Fire.  

(10-Apr-2021, 11:29 PM)iFly4rotors Wrote: Hi JSchubz,

For the original specifications of 1103 motors which we don't really know the rating, but know the specs are 2S a 470 uf capacitor would be fine. No problem. 

Now, the new and marginal specifications of running a 3S or higher battery changes things a bit. Will the 470 uf capacitor be enough, well...maybe...and maybe not.  Keeping in mind that we don't know the rating of the motors, so anything over 2S has the potential to fry them, therefore, a larger capacitor might, or might not, help. The larger capacitor WILL absorb more energy.  

It is not so much that the answer is different, but rather that the criteria has changed which could marginalize the motors.

I use 470 uf only on 2S quads or for a specialized quad. I use 1000 uf on my builds intended for 3S or larger batteries.

How big of a fire extinguisher you need depends on the size of the Fire.  

Thanks for the reply, iFly4Rotors,

I guess I'm a little surprised then, the Hifionrc F7 25A came stock with a 470uf 35v, and is rated from 2S to 4S. Yes, I realize the 1103 motors will be the weak link, but that AIO will obviously run much larger motors. If that being the case, why don't they include a larger capacitor?

Along with batteries, props and tuning in Betaflight, I hardly know squat about caps.

Of what a remember about caps, they used to be red, came in a rolled up shape, and I got yelled at for doing it in the house....same?

-Jeff

EDIT- I see RDQ offers both Panasonic, 1000uf 35v, and 1000uf, 50v. Is there such thing as too big of a cap? I see those are the largest they offer, and read the reviews there, that they are "great on 6S quads".

It ain't quite gonna break the bank if I drop another $1.59 into this build, should I do it now as future proofing?

Hi JSchubz,

Yeah, I know, but I never use those 470 uf capacitors {I keep them for smaller builds...just me, I guess}. So, the 470 uf caps should be fine. On the other hand, the bigger the cap, the more energy it will absorb. Also, the bigger caps are harder to find a good place to put them. So, it will likely be ok to use the 470 uf capacitor since you probably already have one of those, but likely no 1000 uf caps. 

Everything is subjective and I tend to err on the side of caution; just the way I am. Ultimately, the decision is yours.