Servo tester

[Peter Jenkins]

14 minutes ago, Brian Cooper said:

 

Failed during cycling. . . About 20 minutes into the procedure. 

They became hot, slowed down and finally stopped.... they had died. 

 

If they had been installed in a model, they would worked.... but not for long.

They would have cost a model. 

Dare I ask which make of servo?  Alternatively, were they main stream brands (Futaba, JR, Savox, Align etc) or lesser brands?

[Basil]

14 minutes ago, Peter Jenkins said:

Dare I ask which make of servo?  Alternatively, were they main stream brands (Futaba, JR, Savox, Align etc) or lesser brands?

It was a well known lesser brand, that has a good name. I dont want to darken a particular brand.

Bas

[leccyflyer]

Peter was asking Brian which make of servo Bas - Brian's edited his post to show that they were fake Futaba servos.

[leccyflyer]

1 hour ago, Learner said:

Do you all test/exercise your other new components transmitter,receiver,motor,esc etc for an hour before committing to flight or is it just servos?

 Have only tested certain servos, which have a history of failure and, unfortunately, even the testing wasn't able to weed out the weaklings on one occasion. I'd never of dreamed of testing the gear over that critical period before suffering a spate of Durafly servo failures. I really don't like running motors for an extended period of time on the ground, rather than in the air and I'd imagine that  receivers/transmitters are best dealt with in the wild, in a range test environment, rather than on the bench.

[Basil]

7 hours ago, Learner said:

Do you all test/exercise your other new components transmitter,receiver,motor,esc etc for an hour before committing to flight or is it just servos?

The idea is to test when fitting during a build. I am informed by a supplier that servos are more likely to fail when first used from new. Most servos last for years.

This does not rule out the normal preflight checks on all controls  etc.

Bas

[Paul De Tourtoulon]

6 hours ago, Basil said:

It was a well known lesser brand, that has a good name. I dont want to darken a particular brand.

Bas

So just wait and let someone else crash their plane ?.😡

 

At least tell us what particular servo as it could only be one model.

Edited March 7 by Paul De Tourtoulon

[Basil]

16 hours ago, Paul De Tourtoulon said:

So just wait and let someone else crash their plane ?.😡

 

At least tell us what particular servo as it could only be one model.

This post is not about faulty servos, the servos perform as required when tested in situ and under normal working conditions. The post , as far as I am concerned is more about the use of a servo tester than a servo.  There are earlier posts that report  similar happenings to mine. I think we are asking why should a tester driven by a dry cell rather than a Lipo react in a certain way with some servos rather than all servos. l At no point have I referred to the failure of a servo.

Bas

Edited March 8 by Basil

[leccyflyer]

25 minutes ago, Basil said:

This post is not about faulty servos, the servos perform as required when tested in situ and under normal working conditions. The post , as far as I am concerned is more about the use of a servo tester than a servo.  There are earlier posts that report  similar happenings to mine. I think we are asking why should a tester driven by a dry cell rather than a Lipo react in a certain way with some servos rather than all servos. l At no point have I referred to the failure of a servo.

Bas

What exactly do you mean by "a dry cell"?  AFAIK the wee blue servo testers are meant to be operated from a 5v supply, such as would be provided by a 4.8v, 4 cell, Nimh pack. I suppose you could use the regulated supply from a BEC at 5v, but you'd never connect a lipo directly to them.

[Martin Harris - Moderator]

Dry cells are non rechargeable cells (e.g. torch batteries) nominally 1.5V They come from many sources - some better than others (weight is often a clue) and with different chemistries (e.g. zinc-carbon, zinc-chloride, alkaline) so perhaps may suffer from greater voltage drop under load. 

[leccyflyer]

I know what a dry cell is Martin, I'm just trying to find out what Bas means, as the most common forms of dry cell would either be too low voltage (1.5V in the case of AAA, AA, C, C, D batteries) or too high a voltage (9v -PP3, PP9) for those servo testers.

[Martin Harris - Moderator]

I thought it was odd that you were asking such a question!

 

I’d assumed he’d be using a 4 cell holder but I suppose he might be using a 4.5V pack if they’re still available? Haven’t seen one in years…or a 90v battery either for that matter.  I wonder if they’d even be allowed to sell them these days!

[Andy Stephenson]

I have noticed that a 4cell dry battery isn't man enough to operate a servo on a tester, I either use a NiMH or a LifFe pack to supply enough current.

On another tack, I have also had a servo tester fail, it was one of those cheap metal clad ones, They are fairly useless for set-up purposes because the centre setting is quite far from centre.

[Basil]

1 hour ago, Martin Harris - Moderator said:

I thought it was odd that you were asking such a question!

 

I’d assumed he’d be using a 4 cell holder but I suppose he might be using a 4.5V pack if they’re still available? Haven’t seen one in years…or a 90v battery either for that matter.  I wonder if they’d even be allowed to sell them these days!

Yes Martin, a 4 cell holder, it was 5.7v. at the time. ( 4x rechargeable @ 2100mAh )For the last 2-4 yrs I have used this set up with no problems  !!!!!!.

Andy, you said 'Not man enough' , please elaborate.

Bas

Edited March 8 by Basil

[Geoff S]

1 hour ago, Martin Harris - Moderator said:

I thought it was odd that you were asking such a question!

 

I’d assumed he’d be using a 4 cell holder but I suppose he might be using a 4.5V pack if they’re still available? Haven’t seen one in years…or a 90v battery either for that matter.  I wonder if they’d even be allowed to sell them these days!

We used to sell 90v batteries for battery only radios, mostly used by those with no mains electricity (still quite common in my birthplace in the 1940s/50s).  What were useful for experimenters were the grid bias batteries that had outputs of various voltages up to 9v in 1.5v steps from zero.  Not sure why they were needed, as grid bias is easy to design into the circuit with a resistor in the cathode.

 

Flat 4.5v batteries also seem to have disappeared.  My first head torch used them.  Anyway, LED torches are better in every respect.

[leccyflyer]

1 hour ago, Basil said:

Yes Martin, a 4 cell holder, it was 5.7v. at the time. ( 4x rechargeable @ 2100mAh )For the last 2-4 yrs I have used this set up with no problems  !!!!!!.

Andy, you said 'Not man enough' , please elaborate.

Bas

So not a dry cell at all, rather four rechargeable Nimhs, Thanks for the confirmation.

[RottenRow]

They are still technically dry cells, as opposed to wet cells (typically lead acid).

 

Non-rechargeable dry cells are known as primary cells; rechargeable ones (of any type) are secondary cells.

 

The old 4.5V flat batteries (Ever Ready 1289 etc.) are still available, though probably not in the battery display at your local Tesco. The IEC number for them is 3LR12.

 

I used to use these in small Keil Kraft model boats, free running, not R/C. The phosphor bronze connectors were reusable to make pickups for model trains once the batteries had died.

 

https://www.batterystation.co.uk/panasonic-zinc-3lr12-4-5v-battery-1-pack/

 

Brian.

[leccyflyer]

Understood, but Basil had said that he was seeing differences in operation between using A dry cell and using a lipo. I was seeking to clarify what exactly he meant by A dry cell, as it could have been relevant to the issues he was seeing.

[PatMc]

4 hours ago, Basil said:

Yes Martin, a 4 cell holder, it was 5.7v. at the time. ( 4x rechargeable @ 2100mAh )For the last 2-4 yrs I have used this set up with no problems  !!!!!!.

Andy, you said 'Not man enough' , please elaborate.

Bas

That's not 5.7v under load, is it ? 

What voltage is the battery holding whilst the servo tester is being used/attempting to be used ? 

[Basil]

15 hours ago, PatMc said:

That's not 5.7v under load, is it ? 

What voltage is the battery holding whilst the servo tester is being used/attempting to be used ? 

In a nut shell I dont know!!!! . I will have to check, I see where you are coming from. Bear in mind that most servos work with the 4 cell set up !.

Bas

[FlyinFlynn]

20 hours ago, Geoff S said:

.........  Anyway, LED torches are better in every respect.

 

Except for the strobing effect that manifests itself when filming under LED lighting or the blessed power company squirting data over the mains feed propelling my overhead LED lamp into frantic spasms. 🤪

[Basil]

17 hours ago, PatMc said:

That's not 5.7v under load, is it ? 

What voltage is the battery holding whilst the servo tester is being used/attempting to be used ? 

The voltage shows on the meter at 5.3v (Flashing up) down to 4.8v ( flashing up) .So; oscillating from 5.3 - 4.8 as it lights up all 3 lights ( Selection button not working) arm only part of normal travel, back and forth. This occurs with various servos, not just the one you want the name of.

Bas

Edited March 9 by Basil

[Phil Green]

If the voltage measured at any point is varying by half a volt then either the battery has too high an ESR, the wiring isnt heavy enough for the current, or the connectors are resistive. One servo load should barely impact the voltage.

Where are you measuring Bas?  to measure battery volts under load you need to connect the probes at the battery  terminals or a Kelvin connection (ie a separate zero-load connection to the actual terminals), not midway along any wiring - thats a different test, check if the battery is dropping under load first.   Lipo balance leads for example are Kelvin connections - the idea is to measure independently of any cable and load losses.

Edited March 9 by Phil Green

[Geoff S]

1 hour ago, FlyinFlynn said:

 

Except for the strobing effect that manifests itself when filming under LED lighting or the blessed power company squirting data over the mains feed propelling my overhead LED lamp into frantic spasms. 🤪

 

That is only a problem with mains LED bulbs - an LED torch runs off DC.  Mains LED bulbs have a (probably? I've never checked) switched mode converter from mains to dc, which must be causing you a problem.  I think eventually houses will have a separate DC circuit for lighting with just one relatively powerful DC power supply, rather like the server power supply I use for my LiPo chargers.

 

But this is grossly off-topic 🙂

[Engine Doctor]

It might be worth checking each cell under load as Nimhs like many cells can read a good voltage but collapse completely under load, even a light load. Also try a different pack before junking the tester. I use a welded pack as the battery holders are notorious for poor connection and could cause the problems your experiencing.

[Robert Cracknell]

I have a number of Ni-Mh cells that I would like to check out more thoroughly. Sure, they seem to charge OK but you are correct in that they might collapse under load.

What is the consensus on what the load should be and the best way to apply it? Has anyone designed a simple circuit that will apply a constant load while the voltage is checked? What can be used as the load - bulb, resistor..?

What is your favourite method?

Edited March 10 by Robert Cracknell
Addition