Puffing packs - edf jet

[TonyS]

I’ve a problem. I have a Hobbyking Phazer. It’s a small foamy edf that I use for a bit of fun and flying practice. It was built for a 3s battery or so the sales spiel goes.

the last two times I’ve flown it with a 3s 30C 1800 pack, the packs have puffed up and been red hot on landing.

ive bought a slightly larger 3s pack that is rated at 60c which I hope will last a bit longer. Would a 4s pack be better at handling the loads or would that simply fry the ESC and motor?

[MattyB]

No, 4S will do the opposite of what you want; current and watts will go up, and you may fry your ESC and/or motor if they exceed their ratings. You’ve done the right thing to increase the C rating of the battery, but before you fly it put it on the wattmeter and see what figures you are getting so you know if you need to do any throttle management.

[Simon Chaddock]

TonyS

It really will pay to find out how many amps the motor is taking at full power on a fully charged new battery.

A 'good' 1800 mAh 30C pack should be able to deliver 54A but only for 2 minutes! Also once it has got really hot its capability is compromised so the next time it will get just as hot yet delivering fewer amps.

A 60 C rated pack should easily handle the amps that damaged the 30C battery but if it is significantly heavier the extra weight will require the EDF to work that bit harder for the same performance.

EDFs are inefficient copared to a prop so they work batteries hard.

[Richard Clark 2]

Posted by TonyS on 11/08/2020 23:49:37:

I’ve a problem. I have a Hobbyking Phazer. It’s a small foamy edf that I use for a bit of fun and flying practice. It was built for a 3s battery or so the sales spiel goes.

the last two times I’ve flown it with a 3s 30C 1800 pack, the packs have puffed up and been red hot on landing.

ive bought a slightly larger 3s pack that is rated at 60c which I hope will last a bit longer. Would a 4s pack be better at handling the loads or would that simply fry the ESC and motor?

 

As MattyB says 4S will make it worse. The current will go up, not down.

So you have done the right thing in buying a higher C rated battery.

But even then, do NOT believe the C rating, as Simon appears to do. It is nonsense, just pure marketing hype. Though a 60C rated battery is likely to deliver the same or a little more current as a 30C rated one of the same capacity due to a lower voltage drop than the 30C one. This may marginally improve the performance even with the battery probably being slightly heavier, and the battery should not get so hot.

Edited By David Ashby - Moderator on 12/08/2020 10:27:28

[TonyS]

Thanks everyone.
it’s frustrating that almost anything I’ve put in this plane is getting wrecked.
I do manage throttle and only have it running ‘flat out’ on WOT for a few seconds at a time. Proving to be expensive flying. I’m wondering whether cheap ESCs or motors are more likely to damage batteries 🤔

[Frank Skilbeck]

The fact that they are red hot on landing is the problem it is the heat that damages the batteries, which is down to two things, the internal resistance of the battery (higher C rating should be a lower resistance) or very poor cooling. Cheap ESCs or motors might reduce the efficiency a bit so the battery has to put out a bit more for the same motor output but they will not intrinsically damage a battery.

Not all battery makes ore the same, and unfortunately price isn't a good measure of quality either.

[Keith Miles 2]

Posted by TonyS on 12/08/2020 07:20:02:

Thanks everyone.
it’s frustrating that almost anything I’ve put in this plane is getting wrecked.
I do manage throttle and only have it running ‘flat out’ on WOT for a few seconds at a time. Proving to be expensive flying. I’m wondering whether cheap ESCs or motors are more likely to damage batteries 🤔

I know next to nothing about EDFs but an experienced colleague has one, bought new, that has eaten two or three motors and a fan in fairly quick succession and for no immediately obvious reason. Not sure about the batteries, though.

He, too, is not a happy chappie!

It does make one wonder if a few designs are inherently flawed and/or not properly tested before they enter the market.

Good luck with the battery upgrade. Certainly worth trying. Don’t buy too many just yet, though!

[ken anderson.]

tony,i would have a go with a watt meter,sounds like too much is getting pulled out of the battery's...you mention they are Hot...I would treat them with caution in case they Pop...don't waste any more batts until you've determined whats going on...

ken anderson...ne..1..watt meter dept.

[Engine Doctor]

Agree with all above , need higher C rated battery. A lot of these ready to go models seem to quote battery sizes and C ratings that make the model look more attractive to the purchaser knowing full well that you stand no chance of a refund if it ruins a battery or burns out. The watt meter is the way to go.

[Simon Chaddock]

TonyS

If you can tell us what EDF it is and ideally the specification of the fan and motor we might be able to determine what is supposed to be happening which should help once you have measured what is actually happening.

It is also possible some else may have bought the same plane so would be able to confirm or not if there is a particular problem with yours.

[TonyS]

Looking at the set-up I suspect a big part of the problem is the lack of any airflow in the battery compartment. Worse than that it's a very snug fit in a foam cavity - like a hot water cylinder jacket!!

Might be time to start punching holes!!

[MattyB]

Posted by TonyS on 12/08/2020 10:59:47:

Looking at the set-up I suspect a big part of the problem is the lack of any airflow in the battery compartment. Worse than that it's a very snug fit in a foam cavity - like a hot water cylinder jacket!!

Might be time to start punching holes!!

There is a long thread over on RCGroups about this model - might be worth a trawl to see if others have had these issues and if so how they addressed them...

PS - I see what you mean about the layout, there can't be much airflow getting to the pack in it's foam tomb...

Edited By MattyB on 12/08/2020 11:30:07

[Richard Clark 2]

Posted by MattyB on 12/08/2020 11:27:07:

Posted by TonyS on 12/08/2020 10:59:47:

Looking at the set-up I suspect a big part of the problem is the lack of any airflow in the battery compartment. Worse than that it's a very snug fit in a foam cavity - like a hot water cylinder jacket!!

Might be time to start punching holes!!

There is a long thread over on RCGroups about this model - might be worth a trawl to see if others have had these issues and if so how they addressed them...

PS - I see what you mean about the layout, there can't be much airflow getting to the pack in it's foam tomb...

Edited By MattyB on 12/08/2020 11:30:07

It seems to fly very well.

[perttime]

Wouldn't Voltage sag, if you are drawing more Amps than the battery can handle, end the ESC intervene?

The lack of airflow past the pack cannot be good.

[Frank Skilbeck]

Posted by perttime on 12/08/2020 11:40:48:

Wouldn't Voltage sag, if you are drawing more Amps than the battery can handle, end the ESC intervene?

Not necessarily, if the 3s pack had a resistance of 0.01 ohms per cell, then at 30 amps this is a 0.9v voltage drop across the battery pack, which in turn is 27 watts dissipated as heat. If the cell resistance was 0.005 ohms then this drops to 14 watts.

[Keith Miles 2]

Posted by Richard Clark 2 on 12/08/2020 11:33:53

It seems to fly very well.

Sounds like it might fry very well, too!

[Bob Cotsford]

Could you cut some grooves in the foam tomb to encourage a bit more flow around the battery in combination with a hole in the front of the hatch? They wouldn't need to be deep but width counts, just leave enough foam in contact with the battery to locate it properly.

[J D 8]

My Phase 3 EF 16 is quite hard on battery's One problem with EDF types I find is that to get the most fun flying one tends to fly flat out a lot of the time.

The EF16 has a hole at the front of the canopy that sends some cooling air over the batt which I later enlarged to increase the flow. ESC is in the duct roof and has plenty of cooling.

[Keith Miles 2]

TonyS,

Referring back to your original post, would I be correct to assume that the model was originally okay or has this always been an issue?

You also said that “everything” you put in is being wrecked. Do you mean just different batteries or have you replaced other components?

Even my very limited knowledge of electric models suggests that it is, primarily, the ESC that needs adequate airflow rather than the battery.

On reflection, I agree with those who suggest a power check (both watts and current) to begin with to see if the figures are what they should be or are excessive. You can then determine whether or not you are using a battery of too low a C rating or whether you have a problem elsewhere.

No point in buying and fitting a higher C rating battery if it is merely masking a fault!

Edited By Keith Miles 2 on 12/08/2020 13:53:41

[Lima Hotel Foxtrot]

Posted by Richard Clark 2 on 12/08/2020 04:49:40:

Posted by TonyS on 11/08/2020 23:49:37:

I’ve a problem. I have a Hobbyking Phazer. It’s a small foamy edf that I use for a bit of fun and flying practice. It was built for a 3s battery or so the sales spiel goes.

the last two times I’ve flown it with a 3s 30C 1800 pack, the packs have puffed up and been red hot on landing.

ive bought a slightly larger 3s pack that is rated at 60c which I hope will last a bit longer. Would a 4s pack be better at handling the loads or would that simply fry the ESC and motor?

As MattyB says 4S will make it worse. The current will go up, not down.

So you have done the right thing in buying a higher C rated battery.

But even then, do NOT believe the C rating, as Simon appears to do. It is nonsense, just pure marketing hype. Though a 60C rated battery is likely to deliver the same or a little more current as a 30C rated one of the same capacity due to a lower voltage drop than the 30C one. This may marginally improve the performance even with the battery probably being slightly heavier, and the battery should not get so hot.

Edited By David Ashby - Moderator on 12/08/2020 10:27:28

Also don't take as gospel what people write on here when they state it as a fact and slam other users, take your research from a multiplicity of sources.

It is clear that your packs have puffing due to heat and stressful current draw, in my opinion (based on my personal experience) you would be better off leaving packs aimed at fixed wing alone and go for the higher rated multirotor race packs which can deliver very high C ratings for short durations without damage.

[Trevor]

Firstly, I agree your first step should be to measure the current being drawn at full throttle so you know what’s going on. As well as enabling you to avoid abusing the batteries, this will also tell you whether you’re over-stressing the motor and/or ESC.

Secondly, consider investing in a charger that can measure the EIR (Equivalent Internal Resistance) of your batteries (any of the iCharger range will do this). You can then keep track of the real current delivery capability of your batteries rather than trust in the (largely fictional) C rating on the label which, at best, is only relevant when the batteries are new.

Thirdly, What flight duration are you getting? Simple arithmetic says that if you fly for 6 minutes, your average current draw is below 10C. Even if the battery goes flat after 3min,, you’re still only averaging 20C so, if the label is to be believed, even a cheap 20C battery should barely break sweat. We all know that isn’t the case - hence why you shouldn’t take too much notice of claimed C ratings. However, if you are getting flights of 4 to 4.5minutes without totally flattening your battery, then any reasonable quality LiPo should cope reasonably well. If it’s getting too hot to touch then something is seriously wrong.

Trevor

[Nigel R]

Claimed C ratings... trouble is, you don't get told what that limit actually means. 20C before a slight decrease in capacity will occur... or 20C before fire breaks out in a cell...

[Keith Miles 2]

Posted by Nigel R on 12/08/2020 14:41:29:

Claimed C ratings... trouble is, you don't get told what that limit actually means. 20C before a slight decrease in capacity will occur... or 20C before fire breaks out in a cell...

The former for marketing purposes, the latter in reality, of course!

Silly boy.

😊

[MattyB]

Posted by Lima Hotel Foxtrot on 12/08/2020 13:29:23:

Posted by Richard Clark 2 on 12/08/2020 04:49:40:

Posted by TonyS on 11/08/2020 23:49:37:

I’ve a problem. I have a Hobbyking Phazer. It’s a small foamy edf that I use for a bit of fun and flying practice. It was built for a 3s battery or so the sales spiel goes.

the last two times I’ve flown it with a 3s 30C 1800 pack, the packs have puffed up and been red hot on landing.

ive bought a slightly larger 3s pack that is rated at 60c which I hope will last a bit longer. Would a 4s pack be better at handling the loads or would that simply fry the ESC and motor?

As MattyB says 4S will make it worse. The current will go up, not down.

So you have done the right thing in buying a higher C rated battery.

But even then, do NOT believe the C rating, as Simon appears to do. It is nonsense, just pure marketing hype. Though a 60C rated battery is likely to deliver the same or a little more current as a 30C rated one of the same capacity due to a lower voltage drop than the 30C one. This may marginally improve the performance even with the battery probably being slightly heavier, and the battery should not get so hot.

Edited By David Ashby - Moderator on 12/08/2020 10:27:28

Also don't take as gospel what people write on here when they state it as a fact and slam other users, take your research from a multiplicity of sources.

Not sure what you are getting at with the last comment Lima - I don't see anyone slamming anyone else in this thread, everyone is agreeing that he should measure the current draw and (ideally) the IR of his packs in order to diagnose the problem. A higher C rating battery will undoubtedly help, but without current draw data it's impossible to know whether it will be enough to solve the problem, or if something else (most likely too high a motor Kv) is causing excessive current drain for the size of packs in use.

Edited By MattyB on 13/08/2020 09:48:45

[Richard Wills 2]

If you're esc has active freewheel (important otherwise you will get excessive esc temps), you could use a 4s pack and limit the throttle to 75% to get the same power output but at lower current and therefore less stress on the packs