RC Helicopter Problem

[rpb424]

I can't read the markings, but you might be onto something:

Single-axis Gyroscope Analog Gyro Module
View attachment 5253

Probably this - https://international.electronica-a...s-gyro-sensor-shipments-over-30-million-mark/

Data sheet - https://www.elecrow.com/download/ENC-03.pdf

Looking at the data sheet, I would guess that what you have omits the high pass filter on the output (for temperature compensation) and the Vref pin is simply coupled to ground, meaning that only three connections back to the main PCB are needed rather than four. Your close-up picture shows what looks like an extra surface mount capacitor that might be doing this.

 

[Black Hole]

Yes, I've come to a similar conclusion. The below was in preparation before you posted:

---

I'm not saying this is the unit used in my chopper (the date code on the LiPo indicates it was manufactured six or seven years ago, and parts change), but this is the best data I can find (on a quick search) for the unit used on the module illustrated in post 19 (Murata ENC-03RC): https://www.openimpulse.com/blog/wp...ENC-03M-Single-Axis-Gyro-Sensor-Datasheet.pdf. As data goes, it's a bit wooly (and reads as a translation).

The points of interest are:

• It is a MEMS (MicroElectroMechanical System), ie a device made using IC-type processing but incorporating mechanical structures by etching parts out of silicon. In this case, a cantilever beam or a tuning fork structure is created, with the electronics needed to make it vibrate. If the structure is subjected to rotation, the Coriolis effect causes the vibrating element to deflect which is then detected and produces the output.
  
  
• There is advice in the datasheet about using more than one of these for different axes: the vibrations in different units can cross-couple through the PCB and affect the output.
  
  
• There is a Vref pin to set the zero point for the internal amps and the DC offset of the output, but the specification for the output voltage at zero rate of turn is Vref±0.6V! Hence the need for trimming. The scale factor is 0.67mV/deg/sec±20%.
  
  
• Now the killer point why this probably isn't the same module as on the chopper: there is nothing on the PCB to provide Vref, and only three wires to the controller board (ground, signal, and power). However, I do think it's in the ballpark.

Looking at the data sheet, I would guess that what you have omits the high pass filter on the output (for temperature compensation) and the Vref pin is simply coupled to ground, meaning that only three connections back to the main PCB are needed rather than four. Your close-up picture shows what looks like an extra surface mount capacitor that might be doing this.

Frankly, it can't work without Vref - you wouldn't to be able to distinguish a negative rate of turn. Connecting Vref to 0V is also outside the operating spec (for the ENC-03). My guess is that the 'copter one has an internal reference generator for Vref, which requires an external pull-up on the pin. And thus, because there is no reference to that on the controller board, there is even more need for manual trimming!

Any output filtering might be on the controller board, at the other end of the 3-wire connecting cable.

 

[Black Hole]

New battery:

 

[Trev]

That's a really nice picture of a battery BH. And so interesting as well.

 

[Luke]

New battery

What's the difference in weight between the two?
And which is the new one?

 

[Black Hole]

On the right - it's 20g.

And it doesn't work. Everything is OK until I start the flight motors, and then something trips out and there is no more action until I power-cycle it.

My guess is that, although the capacity in mAh is the same, the new battery doesn't have the required current handling (low enough internal resistance). The motor control electronics are almost certainly PWM, so the current demand is in instantaneous bursts of full power. I don't know what makes it trip out, I wouldn't have thought voltage drop should do that, but who knows (the control electronics is a "black box").

Anybody need a LiPo battery?

 

[Black Hole]

I don't know what makes it trip out

I think I do. Possibly it's the battery protection detecting the voltage going too low, to avoid over-draining (and thus ruining) the LiPo. If the LiPo (including connecting leads) are too high a resistance, the current demand will drop the voltage without the battery actually being discharged.

One thing I could try is swapping over the power lead (the lead on the new battery is longer and thinner, therefore higher resistance), but I think that is clutching at straws.

 

[prpr]

I think you've just about proved that you shouldn't buy cheap cr@p from Lidl/Aldi.

 

[Black Hole]

Do you think a more "expensive" one bought elsewhere would have lasted better? From what I can gather about LiPos, under the circumstances, I do not agree... unless you mean a "better" one would be more amenable to parts replacement.

 

[Deleted member 473]

RC Helicopters | Buy Online At Nitrotek

Best prices on electric RC helicopters including Esky. Indoor & outdoor remote control helicopter Sale. Find the perfect radio controlled helicopter and RC helicopters parts with free UK delivery.

www.nitrotek.co.uk

Cheap?

 

[MikeSh]

Do you think a more "expensive" one bought elsewhere would have lasted better?

With these sort of things there is 'toy' and there is 'hobby' (and if you include drones, 'commercial/professional'). I think you may be trying to do hobby with a toy - which is possible but often a bit harder than if you start with a better product.

I've done something like this but with a boat - basically replaced the battery and control systems, which wasn't easy.

 

[Deleted member 473]

My RC helicopter is about 6" long and more like a large dragonfly than a helicopter.

 

[Black Hole]

I think you may be trying to do hobby with a toy

I don't think my usage counts as "RC hobbyist" - very much toy. But it's a good quality toy, built well, and I don't think the unavailability of a direct replacement of a LiPo some years later counts against it (see below).

Cheap?

For information, it's this one:



Branded Bladez Toyz (bladeztoyz.co.uk), marketed as "Designed in England, Made in China". That I have been able to take it apart at all is in its favour, the chassis seems solid, and I can accept the double-sided foam tape as a necessary compromise to save weight.

The Bladez Toyz website carries spares for current models, and certainly used to (according to Wayback Machine) offer replacement batteries for some models. Indeed, I ordered a spare set of rotor blades from them.

From what I can make out in my diaries, it was bought from Aldi in June 2012 for £39.99 when other retailers had them for £70.

My RC helicopter is about 6" long and more like a large dragonfly than a helicopter.

I also have a small one, for indoors only, which operates by IR control. The 'copter charges from the batteries in the handset. That one doesn't seem to be working either.

 

[MikeSh]

My RC helicopter is about 6" long and more like a large dragonfly than a helicopter.

I also have a small one, for indoors only, which operates by IR control. The 'copter charges from the batteries in the handset.

SWMBO bought me one of those a few years back. I couldn't fly it (only the real thing it seems), so it got donated to the kids or a charity shop as I knew if it was left lying around the batteries would go to pot.

 

[Black Hole]

I came across this while trying to find out whether "903043" means anything:

Pouch Cell

In 1995, the pouch cell surprised the battery world with a radical new design. Rather than using a metallic cylinder and glass-to-metal electrical feed-through, conductive foil-tabs were welded to the electrodes and brought to the outside in a fully sealed way. Figure 6 illustrates a pouch cell.

​

Figure 6: The pouch cell.​

The pouch cell offers a simple, flexible and lightweight solution to battery design. Some stack pressure is recommended but allowance for swelling must be made. The pouch cells can deliver high load currents but it performs best under light loading conditions and with moderate charging.​

Source: A123​

The pouch cell makes most efficient use of space and achieves 90–95 percent packaging efficiency, the highest among battery packs. Eliminating the metal enclosure reduces weight, but the cell needs support and allowance to expand in the battery compartment. The pouch packs are used in consumer, military and automotive applications. No standardized pouch cells exist; each manufacturer designs its own.

Pouch packs are commonly Li-polymer. Small cells are popular for portable applications requiring high load currents, such as drones and hobby gadgets. The larger cells in the 40Ah range serve in energy storage systems (ESS) because fewer cells simplify the battery design.

Although easily stackable, provision must be made for swelling. While smaller pouch packs can grow 8–10 percent over 500 cycles, large cells may expand to that size in 5,000 cycles. It is best not to stack pouch cells on top of each other but to lay them flat, side by side or allow extra space in between them. Avoid sharp edges that can stress the pouch cells as they expand.

Extreme swelling is a concern. Users of pouch packs have reported up to 3 percent swelling incidents on a poor batch run. The pressure created can crack the battery cover, and in some cases, break the display and electronic circuit boards. Discontinue using an inflated battery and do not puncture the bloating cell in close proximity to heat or fire. The escaping gases can ignite.

So the foam tape construction may be deliberate to allow for normal swelling, and the swelling I've got is normal compared with this:

​

Figure 7: Swollen pouch cell.​

Swelling can occur due to gassing. Improvements are being made with newer designs. Large pouch cells designs experience less swelling. The gases contain mainly CO2 (carbon dioxide) and CO (carbon monoxide).​

Source: Cadex​

...but I don't understand how "gases containing mainly CO₂︎ and CO" can "ignite".

However, it's clear internal delamination would increase the internal resistance and therefore decrease the current the battery is able to supply.

I've also been thinking that these batteries are fitted with protection circuits, and it could be that which is tripping out the new battery. I could try swapping the protection board from the old battery onto the new one and see what happens, there's a risk it might allow the new (thin) battery to over-current... but what the heck.

 

[Ezra Pound]

I came across this while trying to find out whether "903043" means anything:

How close did you look at post #14?

 

[Black Hole]

Of course I have... but that "903043" is not identical to my "903043". I was trying to decode what the numbers mean: are they independent of dimensions and specify the electrical characteristics? I don't know.

 

[Ezra Pound]

Is your new battery 5.2 x 34 x 50 mm by any chance?

there are some clues in the picture that post #14 pointed to :-

 

[Black Hole]

The penny drops.

But the original battery was:

3.7V
1000mAh
JST connector*
28g
55x32x11mm overall

...as measured, which (by your reckoning) should be 1103255, and yet it is marked 903043. Now I know what I'm looking for, I can get the thickness to near 9.0 and the width near 30, but no way can I accept the overall length as 43 - actually the battery part is about 43, the tabs and protection board take it up to about 52.

The new battery is marked 523450, and measures 5.3 x 34.6 x ~51.4 overall.

So maybe standards have changed since 2012 and used to be the size of the battery itself but are now overall?

If that's the case, the same code today is for a battery which is smaller than before.

Note this is only supposition. I have not found anything on the web to say that is what the numbers really mean.

 

[Black Hole]

I've also been thinking that these batteries are fitted with protection circuits, and it could be that which is tripping out the new battery. I could try swapping the protection board from the old battery onto the new one and see what happens, there's a risk it might allow the new (thin) battery to over-current... but what the heck.

Done it, works (sort of).

The chopper no longer cuts out on max input, but the lift is lacking as before. I guess this is the internal resistance of the thinner battery (which must have a lower capacity despite what it says on the label).

Unfortunately the listings for these various batteries do not specify the max drain current or internal resistance.

I seem to have a choice: order that very long lead "903043" item from Aliexpress, or try a 2000mAh unit (which seems to have the right general dimensions) on the presumption that higher capacity = greater current capability.