79 replies to this topic

[Wrcallar]

4aa batteries is the same as 6v then?

Thanks, I can do some more trouble shooting when my other 2 esc's turn up and my new servo's. Thanks

[cbr6fs]

Wrcallar, on 15 August 2011 - 09:00 PM, said:

4aa batteries is the same as 6v then?

Thanks, I can do some more trouble shooting when my other 2 esc's turn up and my new servo's. Thanks

The total voltage will depends on the batteries charge and chemistry (NiMh, Alkaline etc etc) but 4 x AA batteries will be as close to 6v as makes no difference  

[Wrcallar]

So could a dodgy crappy esc BEC be supplying the right voltage but not enough current? Or are you saying that they tend to supply the drawn amount of current but at a to low voltage?


In my situation, say it was a faulty servo.


ezrun 35A BEC output: 6V at a poor 1.5A!
Towerpro MG995 servo: Operating voltage 4.8-7.2V with no A draw spec.


Is it possible the servo could be demanding more current than 1.5A? If so what would happen, would the esc shut down or would the servo fail? I take it the motor doesn't draw any current from the BEC?


My symptons are:


-I hold left on my Spekky and the wheels turn left, then centre, then left, then centre. Same with right. Sometimes the wheels don't work at all. When it centres, my SR300 light turns off momentarily.
-Throttle works fine on it's own, cuts out when I steer though.


So I think the esc is going into failsafe mode when the rx light turns off and wheels centre.


I tested the servo and it worked fine with a losi 1/18 esc I had sitting around so I actually think it's the ezrun esc that's the issue. How can I test if the BEC isn't giving out enough current and is then putting itself into failsafe mode?


Cheers

[Wrcallar]

I also tested another spekky RX and it did exactly the same thing so it's not the spekky overloading

BUT I can't put all the blame on the ezrun esc because it works fine on my new MERV servo! But my last stock merv servo died after about 10 minutes use with the ezrun, can't be sure it's related but i'm cautious about using thee 35A in my MERV instead of my mad monkey incase it kills me second merv servo somehow? :/

Edited by Wrcallar, 15 August 2011 - 09:27 PM.

[cbr6fs]

It could well be the servo drawing more current than the Esc/BEC can supply.
Fly in the ointment there though is it's a pretty bog basic servo, so unless something is binding i can't see it meself.


What Tx are you using, can the end points be adjusted?
I've seen similar problems when end points are poorly adjusted.


Other thing i'd check is binding.
Remover the steering linkage and see how free the steering is.

[Wrcallar]

DX3C and I think I adjusted the steering end point but will double check this weekend when I'm back home cheers

I'll also check for binding too as suggested thanks  

Wayne

[cbr6fs]

As you say, if the Esc/BEC powers the servo fine in your other car then chances are it's.

1/ End points
2/ Binding
3/ Dodgey servo

Off the top of my head if it's not the Rx or Esc/BEC then the listed above are the usual suspects.




Good luck

[Jefferson]

Just checking I have this right...

Get an external bec, wire in to the relevant + - battery connectors at esc side

Bec is then connected to receiver - just plug in

I then need to disable the current power from the esc to the rx, I'd get a short servo extension cable but remove or disable the red power wire, this ensures I can still use the esc  to program card function?

Cheers

[manamp27]

So I just installed the castle bec as per the second diagram on page 1 of this thread. The bec is linked to the battery cable and feeding power direct to the servo, while the receiver is feeding the steering signal only to the servo.

The problem I am having is that every time I come off the throttle, the steering locks to the left. It's like something is interfering with the steering signal.

Any ideas?

[cbr6fs]

That's a weird one.

Here's what i'd do, remove the plug from the steering position (on the Rx) and plug it into the throttle position.

Now try that, the steering servo should now move with the throttle.
If it does then try moving the steering and see if you get the same problem as you were getting before.

If you are then 100% it's your wiring.


To prove the Rx is ok, just plug the servo directly into the Rx and try again.
If it does exactly the same thing it sounds to me as though something is wrong with the Rx or your Tx is programmed into some kind of mixing mode.

[manamp27]

Thanks mate. Before I try that, I just thought of something else.

I'm using a 2 channel Futaba 2.4G system. Ch1 is for steering, Ch2 is for throttle. It has an auxiliary slot for powering a 2nd fan.

Can I use this slot to plug the BEC into (as per option 1 in the diagram of pg1 in this thread) or is this auxiliary slot only designed to output power, rather than receive power?

Edited by manamp27, 23 October 2011 - 10:31 AM.

[cbr6fs]

Yep, i can't think of any reason why not.

Make sure you remove the power wire from the Esc though, otherwise you'll have power going into the Rx from the Esc AND the BEC which could well burn it out.

Do not cut the Esc power wire though if (like in the case of Castle Esc's and XeRuns) you need to use the Rx plug to program the Esc.

[manamp27]

All sorted. Thanks for your help. Plugged the bec direct into the auxiliary port on the receiver, steering to ch1, throttle to ch2, fan to ch3.

I'm surprised ch3 outputs power, given it's a 2 channel radio system.

Thanks again.

[J450n]

Hi Peeps,

Just Read through this and I'm having a  "Beaker moment",  It apears I was wrongly advised that bec's are only for nitro's,

I'm Using flux motiv esc (7.2v) and standard HPI firestorm servo (6v) and Ansmann Racing 3.1 RX.

Is it still advisable to use a bec with this setup or wait till I have to replace the servo with somthing better?

Cheers

Jason

[RoughRiderBX]

I run a 6s lipo on my brushless losi 8ight T though i use a hobbyking esc. How do I program it if it isnt an MMM esc?
Jay