Changing from 6v to 12v

[Neil AnyonParticipant @neilanyon41955]

Effect on motor speed

[Neil AnyonParticipant @neilanyon41955]

Hi.

I am in the process of refurbishing a model TID tug. This is powered by a Robbe 3:1 geared motor via an Electronize ESC. The boat as built runs from a 4aH 6v battery but she will be rebuilt with 12v (for better smoke generator etc.).

As I understand things, the output of an ESC is effectively a series of pulses at around supply voltage the proportion of on/off determining the average output and hence speed. Am I right in assuming, then, that with a 12v supply the controller will have to give shorter pulses for a given RPM ? I am also guessing that the “range” pot on the controller determines the maximum ratio of on/off rather than the voltage of each pulse. If this is the case is there likely to be a noticeable effect on the slow-speed characteristics of the motor at low throttle openings?

 

As it stands the motor is not especially slow starting but the gearing allows the prop to turn slowly enough for a very smooth acceleration. The speed controller is an old one (14 years or so) but is still perfectly fine. I would just rather make any necessary changes at this stage rather than a few weeks down the line.

 

Any ideas or suggestions would be welcome. Thanks.

[Dave MilbournParticipant @davemilbourn48782]

12v will effectively double the motor speed for any given ESC setting. The voltage at the motor will, as you have gathered, be 12v and not 6v so the range (mark/space ratio) will need to be adjusted to reduce the top speed – as far as is possible.

I don’t know how the Electronize ESC works in this respect i.e. whether it just cuts off the acceleration once it gets to the new top speed or alternatively “stretches out” the new speed range over the full movement of the Tx stick.

I suggest you experiment with the new voltage and the ESC settings before you finally fit the battery into the model. The alternative is to run the smoke etc from a separate 12v supply. Your tug will need ballast anyway so why not put something heavy and useful in there?

Dave M

[Neil AnyonParticipant @neilanyon41955]

Thanks Dave. For simplicity I’d like to stick to a single 12V source for the electrics, and more to the point, I’ve already installed a 12v 4.5Ah battery which is all the ballast I’ll need bar a bit of trimming. I’ve also installed 5v regs for radio, lighting, sound, fan etc. on a DIY distribution board.

 

Once the prop is refitted I’ll run the motor and see what happens. My TX has two ratcheted sticks so I might run throttle and rudder on the RH stick and use the rate switch or even have a Iook at the throttle pot.I was thinking of doing this anyway and keeping the LH stick for the Quad Switch and other switchers.

 

If it doesn’t look like it will work out I’m prepared to change the ESC. If so, I’ll be back asking for recommendations

Edited By Neil Anyon on 18/12/2011 18:04:55

Edited By Neil Anyon on 18/12/2011 18:06:09

[ashley needhamParticipant @ashleyneedham69188]

OR…. fit a smaller or finer pitch prop, as this will be spinning faster… this would effectivly “gear down”the motor ??

 

Ashley

[Neil AnyonParticipant @neilanyon41955]

Thanks anyway Ashley but I’d prefer to stay with the existing prop. It is very close to scale and worked well in the 6v setup. I’ll see how things go; I might be worrying about nothing!

[aquaplanerParticipant @aquaplaner]

Neil..connecting a 6 volt ESC to a 12 volt supply may instantly damage the ESC..so make sure that the maximum input voltage that allowable with ESC..and you can make a voltage converter with a simple electronic circuit, that can be connected from 3 volt to 24 volt, and can adjust its output to any desired range from 3 to 24..by rotating a simple potentiometer..and can calibrate the output voltage after connecting its output to load..it can haul more than 30 amps, and can increas up to 50 with a size of match box..it also acts as a current limiter, so can save battery a lots..try once..have nice running for hours..without over heating..

Edited By aquaplaner on 12/01/2012 19:26:28

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