Strange motor characteristics in new Ryobi electric brushcutter

[tinnews]

I have just bought a Ryobi RBC-1000EX electric brush cutter. It works well and is easy to use, I have also got some attachments for it and overall I'm quite impressed.

However there is one oddity about it which I can't quite fathom out. The motor just has a straightforward on/off switch (with interlock) there is no sort of speed control or anything like that but when using the machine the motor starts in a sort 'half-power' mode and then after what feels like a random interval switches itself up to full power.

Once in 'full-power' mode it never goes back to the half-power start up mode until you switch off, then it repeats the process. There is no mention at all in any of the manuals about this 'soft start' and the problem is that I don't really understand how to get it into full power mode on demand. Sometimes it stays in the low power mode for ages before speeding up.

It *seems* as if it goes up into full-power mode when you load the motor as, when I was strimming last night, it always went into full power mode pretty promptly when I attacked banks of stinging nettles. It's not 100% guaranteed though.

Has anyone else experiences this sort of motor control? Is it just a 'soft start' or what? Have I got a faulty one - should it switch up to full power more quickly and/or reliably?

[Tim..]

If indeed it has a soft start, then yes it should switch to full power at the same point everytime you start it up.

Tim..

[tinnews]

I took a quick look inside, I'm pretty sure it does have some sort of soft start, there's an 8-bit microcontroller with 2k of Flash RAM, some ROM, etc. with an SCR or something to control the motor.

The trouble is that the manual gives no clue at all as to how the soft start works, how it decides when to go to full power, etc. so I don't know whether it's working "as designed" or not.

The technical help line at Ryobi wasn't much help either.

[Andy Hall]

If you're worried about it why not just take it back to the retailer and tell them that it's running intermittently and ask for a replacement.

It doesn't look as though you will get a sensible answer otherwise and one would think that it ought to behave consistently.

[tinnews]

That's what I'm doing.

I'm just a bit worried that the microcontroller does mean that the soft start does 'clever things' and, without knowing what they are, it's difficult to tell whether it is working as intended.

Oh well, we'll see what happens when I get the replacement.

It's an excellent machine!