Motor cuts when steering?!

[Cardnim]

Setting up the Cat for oOple race and noticed that when I steer, the motor "stutters"

That is to say that it doesnt cut out but definately drops the revs for a short blip then comes back.
This seems to happen only when going slowly (or it might be that I dont notice the small drop when at higher speeds)

Any ideas what might be causing this?

[fidspeed]

the usual culprit tends to be a weak BEC in the ESC combined with a "large" current drain from the servo

the usual supects are savox servos and spektrum RXs ( not exclusively however ) reading similiar posts those two names crop up regularly

a power cap pluggesd into a spare RX port can help eliminate this

no guarantees on success

i have mainly spektrum rx and some savox servos and have occasionally suffered this ( running 1s lipo, spekky rx and savox servo is a deffo no-no and requires a lipo booster

Fid

[Cardnim]

Cheers FID.
I had suspected the BEC too, but hoped against that.

You're spot on with the servo - a Savox 1258TG
the ESC is a SpeedPassion GT2 (LPF)

Never used a power cap before. Are these an RC item available from shops, or is a standard capacitor of suitable rating?

[MiCk B.]

Hey,

Something like this is what you are after:

http://msdmodels.ie/zencart/index.ph...roducts_id=231




Receiver plug already fitted.

MiCk B. :-)

[Cardnim]

Mick - always there with a helping hand!!

Any chance of sending one over to oOple with Derek and the rest of the guys?
Will you see them before the race?

PM me if possible.
Ta muchly!

[fidspeed]

spektrum do them i think there about £6-7

the current drain by the servo causes the voltage to drop in the BEC supplying the RX ,causing glitches and issues (worst case is the rx switches off (known as a brownout and common in the RC aircraft world and has caused many a lost plane (personal experience ) quite often we run 5 cell rx nimh packs instead of 4 to keep voltage up when under load (using 4 or more digi servos in elaborate plane set ups )

fitting a power cap into the RX usually just boosts the voltage under high drain situations and helps eliminate problems

Fid

[Cardnim]

Cheers FID.

Something like the cap thats fitted between the battery and the ESC then?
(except its job being to smooth out the power from the lipo cells)

[mark christopher]

Originally Posted by Cardnim

Cheers FID.

Something like the cap thats fitted between the battery and the ESC then?
(except its job being to smooth out the power from the lipo cells)

if you dont get on in time ill lend you one for the weekend or you can get mbmodels to post me one as a replacement and keep mine ( if the new one gets to me before thursday eve i will deliver it trackside friday for you
)
http://www.rccarshop.co.uk/index.php...protector.html

[Cardnim]

Cheers Mark, really appreciate the kind offer.
Think Mick has got me sorted now, but thanks again.

On the wiring side of things - can the power cap plug into ANY free port/channel on the RX?

Im using the FrSky system, and their V8R4 is a 4ch receiver with no obvious "batt" plug marked.

[dmcracing]

Every channel on frsky is battery in battery out,have you checked servo travel?If it over stretches you will cause a short thus a cut in the motor.

[Cardnim]

Thanks Derek - great advice - actually you are spot on.
The motor cut was happening BEFORE i setup the end points on the servo.

Now that they are set, the motor 'stutter' is almost gone - but still slightly present.

The very nice Mick has got me sorted with the power cap for oOple.
See you Thurs!!

[dmcracing]

Good to hear,see ya thur.Your tyres are packed aswell

[KRob]

In case anyone else is suffering, these are now available and cheaper then the other options (although just as good). I run them with my Spektrum recevier and Savox servo. I find I don't need them with the low profile servos - only the really torquey ones.

Etronix Power Cap