Topic: ESC - Dead or Alive ?!?

hi guys!

The title says it all, I own a 'TURNIGY Plush 30amp Speed Controller'. Recently, after a long period of not using it, I connected it to a (what now seems to be) faulty 2 cell LiPo and the battery ballooned up while the ESC heated  . As soon as I noticed I disconnected the battery and disposed it off, wondering whether the ESC was charred as well 

To verify, I removed the outer wrapping of the ESC to see whether anything was burnt, but it all looks fine, nothing seems to have burned from the outside. But, when I tried to test the ESC with a DC power supply unit(can risk another battery!), the ESC did not make that familiar tone when it starts up. The motor was not responding to the throttle and was just getting jerks clockwise and anti-clockwise alternately  , also, when the motor jerked it was pulling almost 2 - 2.5 Amps without any load. What do you suspect is the problem with my ESC ??

Here are the pictures on my ESC -


 

It sounds like you may have connected the battery with reversed polarity - that kills a controller. But failing that it could simply be an intermittant connection on the motor side (ie one of the three motor connections is open-circuit) as this produces the "back and forth jerking" symptom.

Check all the motor connectors/cables from the ESC and test the  continuity of all permutations of the motor cables, flexing the aires while you do it, to find the break.

PDR

The problem may be that the ESC needs to detect a number of cells before it will arm properly so your DC power supply may not be something that it will work with. it depends on the ESC as to what power supply it will use. Otherwise it might well be as PDR says.

@PDR : Tried the same ESC with another working motor, still the same symptom  (I am positive its not the reverse polarity problem with the battery as well, I use such connectors that fit only when the polarity is correct)

@tsr : So we cannot confirm whether the ESC is `bad` with a power supply unit ? Do I have to risk it with a battery ??

Have you got a wattmeter or a clamp meter so that you can see what current the ESC is pulling when connected.

Yes I do..should I use a bettery or a DC power supply unit ?

@tsr : What if I connect exactly 11.1 volts to the ESC through the DC power supply, there is no way an ESC can know whether its a battery or a power supply, shouldn't it work the same way as it does with a battery ?

Hi,
    I recently had a controller and motor show the backwards and forwards twitching you describe, as the system had been lying around for some time in storage I cleaned the contacts (plugs/sockets) with methelated spirit and lo and behold a working system. So it might be worth your while checking your plugs/ sockets for cleanliness.

Mike

....... What if I connect exactly 11.1 volts to the ESC through the DC power supply, there is no way an ESC can know whether its a battery or a power supply, shouldn't it work the same way as it does with a battery ?

It probably would work with 11.1 volts from a DC power supply, BUT:-
1) It would be expecting to see 12.6 volts from a fully charged 3 cell Lipo at connection, so it would have to have been programmed to recognise 11.1 v as a flat 3 cell Lipo.
2) Many DC power supplies still have some ripple in the output voltage which might confuse it - it could look like a dodgy connection or a faulty battery.
3) There could be more variation in voltage under load than from a battery - depends how good the power supply is.

A lot will depend on the software in the ESC, but if it works - it works!
Personally I would use battery for this testing to eliminate the above variables from the results.

Dick

I know several use a psu to drive their ESCs for bench tests so it should work. As DickW said there maybe a problem if the ESC is seeing a switching voltage peak and that will depend on the software in the ESC.
Some Tx will only work with the ESC with the throttle low at the top and that trim needs to be at the low end as well.
When you put the DC power supply on the ESC motor combination did the ESC heat up as it did with the battery?
Other than that it is too clever for me. I would use one of my many old batteries that are no longer in use as they either no longer hold full charge or suffer from increased voltage drop under load. i.e. basically they are knackered, so no loss if they do something interesting.
Sorry not to be useful.

It probably would work with 11.1 volts from a DC power supply, BUT:-
1) It would be expecting to see 12.6 volts from a fully charged 3 cell Lipo at connection, so it would have to have been programmed to recognise 11.1 v as a flat 3 cell Lipo.

Not as I understand it, 11.1v is about middle of the range (ok, slightly lower), voltage cutoff should be closer to 10v. IIRC my esc's are set to high cut off which is either 3.2v or 3.3v per cell. I don't usually run them that flat tho, voltage tends to be mid 10v's when put back on the charger.
The motor /esc should not have probs running on 11.1v, but I would have thought that the esc's cell detection programming would be confused if a DC input was used. I've never tried it tho so I'm just agreeing on a previous post.

Not as I understand it, 11.1v is about middle of the range (ok, slightly lower), voltage cutoff should be closer to 10v. IIRC my esc's are set to high cut off which is either 3.2v or 3.3v per cell. I don't usually run them that flat tho, voltage tends to be mid 10v's when put back on the charger.
The motor /esc should not have probs running on 11.1v, but I would have thought that the esc's cell detection programming would be confused if a DC input was used. I've never tried it tho so I'm just agreeing on a previous post.

Yes I agree 11.1 volts is a pefrectly normal voltage when the motor is running, but that is because the voltage drops under load.

I was talking about the ESCs cell detection when you connect it, not the cutoff voltage under load which is something completely different.
When first connected the ESC would see 12.6 volts from a freshly charged 3 cell Lipo. A Lipo is essentially "flat" at 11.1 volts on no load, and it is (or should be  ) on no load at the time of connection.
Dick

I would use one of my many old batteries that are no longer in use as they either no longer hold full charge or suffer from increased voltage drop under load. i.e. basically they are knackered, so no loss if they do something interesting.

I have an old car battery on a trickle charger sat under my workbench, for general charging and testing use.

I'd definitely use something like that rather than a Lipo that could burst into partcularly nasty flames.

I have an old car battery on a trickle charger sat under my workbench, for general charging and testing use.

If you have a lead-acid battery on charge in an enclosed space then you are at far greater risk of fires (due to liberated oxygen and hydrogen) than you are from a lipo...

PDR

I've had two 12v lead acid batteries blow up. They really do go up well and hurl shards of hard sharp plastic a long way very fast. When you are charging them please ensure you have them well ventilated and no chance of sparks from any other activity.

The sparks one caused the first, angle grinder being used the other side of a workshop, the second was in a car on a charger overnight not sure what happened there but think the battery must have had a fault.

Yes I agree 11.1 volts is a pefrectly normal voltage when the motor is running, but that is because the voltage drops under load.

I was talking about the ESCs cell detection when you connect it, not the cutoff voltage under load which is something completely different.
When first connected the ESC would see 12.6 volts from a freshly charged 3 cell Lipo. A Lipo is essentially "flat" at 11.1 volts on no load, and it is (or should be  ) on no load at the time of connection.
Dick

I see your point, I didn't consider how the motor would load from a 11.1v source, although with it being DC, won't voltage remain constant whether under load or not?

If you have a lead-acid battery on charge in an enclosed space then you are at far greater risk of fires (due to liberated oxygen and hydrogen) than you are from a lipo...

It's in a reasonably large (14'x10') well ventilated room, on a small 6/12V bike trickle charger that only gives a couple of amps at best. I think it's safe enough.... unless you want to persuade me otherwise?

It's in a reasonably large (14'x10') well ventilated room, on a small 6/12V bike trickle charger that only gives a couple of amps at best. I think it's safe enough.... unless you want to persuade me otherwise?

Don't....

Light a fag

Light a blowtorch

Hit anything metal on metal

Flick a switch (I've seen it in the movies)

Make sparks on the floor with studded cricket/football boots

I'll let someone else add a few more reasons....... ...lol

Once full, all the time it's "trickle" charging at a couple of amps it's producing a couple of coulomb's worth (per second) of elecrolysis.

It's a while (call it 30 years and change) since I've done the sums of electrochemistry so I could have dropped a few decimal points, but I make that roughly 1cm³ of hydrogen (plus about half that of oxygen) at standard temp/pressure liberated per second. You can form your own judgement about whether that's a dangerous mount, but standard practice frowns on charging lead-acid cells in enclosed spaces.

PDR

Once full, all the time it's "trickle" charging at a couple of amps it's producing a couple of coulomb's worth (per second) of elecrolysis.

It's a while (call it 30 years and change) since I've done the sums of electrochemistry so I could have dropped a few decimal points, but I make that roughly 1cm³ of hydrogen (plus about half that of oxygen) at standard temp/pressure liberated per second. You can form your own judgement about whether that's a dangerous mount, but standard practice frowns on charging lead-acid cells in enclosed spaces.

PDR

So presumably charging at 10's of amps in a small space that's only open at the bottom (hydrogen being lighter than air) and full of hot metal and sparks would be certain death?

Car bonnets must be a really bad idea then...

But anyway, it isn't trickle charging at a couple of amps, that's full on maximum charging, it switches down for the maintenance phase to as low as 200mA. That's not going to blow up a 55Ah car battery, or cause it to gas much. The charger is designed for permanent connection to say a bike being stored in a garage for the winter.

I agree a basic 6A+ on or off charger would be a bad idea.


Not convinced yet 

The ones that especially tend to blow up are basically on their last legs and there are potentially internal problems so they might be gassing well on one cell, and will not hold charge as they should. Most batteries in good condition with a good condition charger with a trickle charge facility should be moderately safe. The problem occurs when the battery develops the fault with the charger is attached the charger is suddenly going at full belt and the fuse pops in the charger and that is enough, and then while all is quiet in the night, a really good alarm clock goes off. 

The ones that especially tend to blow up are basically on their last legs and there are potentially internal problems so they might be gassing well on one cell, and will not hold charge as they should. Most batteries in good condition with a good condition charger with a trickle charge facility should be moderately safe. The problem occurs when the battery develops the fault with the charger is attached the charger is suddenly going at full belt and the fuse pops in the charger and that is enough, and then while all is quiet in the night, a really good alarm clock goes off.

'Full belt' on this dinky charger being about 10W it turns out now I look it up... that's a whole 0.8A.

'Moderately safe' will do for me on this one. Somebody is in that room every day, so any gradual problems will get noticed. If its been on charge for a bit and I don't have much charging to do for a while (or away on hols etc.) I turn the charger off anyway.

It's a moot point anyway, I've got a 50W switch mode PSU lined up to take over from it for general charging use.

I used to maintain literally dozens of Strowger type PABXs with 50v lead acid batteries on "floating" charge situated on wooden racks adjacent to the switching equipment. The most common types had the equipment housed inside steel cabinets but the doors were open when we were working on them. The larger installations were completely open, often with 2 x 50v batteries adjacent to the switching equipment, ringing machines etc.

Car bonnets must be a really bad idea then...

I don't want to labour this - I've done my "due diligence" by passing on the warning about leaving lead-acids on charge in enclosed spaces so I'm covered!

But on a point of order - car engine bays are extremely well ventillated spaces by design and for lots of reasons. The main reason is simply that around 60% of the engine cooling is direct radiation and convection from the cylinder head, so if the air *didn't* flow freely it would get rather hot in there! There's also the minor detail that in most cars the radiator efflux goes into the engine bay (that's intended to improve warm-up times),

PDR

I see your point, I didn't consider how the motor would load from a 11.1v source, although with it being DC, won't voltage remain constant whether under load or not?

No.
A battery has "internal resistance" and so the voltage it produces will decrease as the load increases in accordance with ohms law. It doesn't matter if it's AC or DC or any other waveform, it's all just electrons flowing as far as the battery is concerned.
A freshly charged 3 cell Lipo off load should be 12.6v (or just under) while a flat one would be about 11.1v. On load the actual voltage depends on the internal resistance of the cells and varies with the load. I have seen as low as 3v per cell from a freshly charged Lipo on extreme load.

It is just possible that an ESC would see 11.1v from a DC power supply as a flat battery and not start properly (though I doubt many are that sophisticated).

Dick

Thanks guys for all the info, I guess I'd try cleaning up the ESC's connections and try it with an old 2 cell lipo before I consider it done.