Do the brush-less motors not modulate their speed?

[AekaGSR]

Hello everyone!  I've had my 3510 for about a month now and I just realized the blade speed never changes.  I've seen videos of others' mowers vary their blade speed.   Just wanted to see if this was normal.

[toolbelt]

Hi, welcome to the forum. 

Not much action lately since it's so cold out.  I can't really answer your question as I have a 3210, but I believe the only time there is a blade speed change is when high grass is encountered.  My Junior (3210) ramps up his cutting motor until the detector tells it that there is no more high grass.  He also has brushes in his motor but I can't see why being brush-less should make a difference.
BTW, are you cutting grass this time of the year???  Most of us are up to our you-know-what in snow or ice.
If you haven't done so already you may want to start back at the beginning of this forum and read though some of the posting.  There is a ton of good stuff that you can use.  I believe Kathy has a book that she sells which contains about everything you would want to know.  email and check with her.

Again, welcome aboard,

toolbelt

[AekaGSR]

Yeah I've been slowly poking around, seeing some interesting ideas.   I live in California, the grass has slowed in growth, so I have it on a limited cycle right now.  We've actually been experiencing an abnormal heat wave for a few weeks while you guys are getting some crazy cold.

I also unfortunately lost the blade guard, it got hit by... the blade.    I lowered the blade a notch and it was fine for a few days until it transversed some terrain in an awkward way, pushing the blade up and into itself crashing and breaking the guard so I pulled it off.   The motor and blade seem fine.  It runs much quieter without that thing anyway.

[toolbelt]

Too bad about the guard.  Kathy (RobotLady) will put a new one on and charge you for it if it's not there should you send it in for repairs.... it's the law.  A lot of folks found that it causes the grass to collect around it to the point that the grass doesn't get cut.  I figure that if you're stupid enough to stand there and let a lawnmower run over your feet you deserve to get your toes cut off!!!  Who in the right mind would let little children play in the yard with a lawnmower running loose.  I have two hanging on my wall.  That's about all they are good for.....

Oh, almost forgot, ya gotta give your bott a name.  Another good reason to read some of the previous postings to find out what others have have chosen for names..... Crazy, sure but what the heck we love these things as they do the work while we sit on our butts....

[RobotLady]

Hi, it could be from your grass not growing right now or it could be that something happened to the blade motor.   It also could be a software issue.

I think you should wait until the grass grows again and see if you still have the problem.  Having actual grass is the only way to test the speed sensor.

RobotLady

[AekaGSR]

Since the first use on a couple weeks of growth it never changed speeds.  I let it grow out a bit and let it run through some thicker patches and it still hasn't ramped up.  I wonder if it is at full speed all of the time but it is hard to compare just by watching youtube.

Haven't named it yet,  I think I'm going to troll the neighbors by putting My Little Pony stickers on it though. Haha.  I'm an angry looking guy so I would find it quite funny.

[RobotLady]

It seems like something is wrong.  It could be a problem with the speed sensor in the blade motor or it could be a software version issue.  Longshot - it could be the motherboard (unlikely, though).

Who did you buy the robot from?  You should try to get help from the dealer who sold it to you.

RobotLady

[AekaGSR]

I got it from someone else    So I sent them an email,  I'll keep you guys updated.

[AekaGSR]

No response so far.  They are closed when I am home so emails are my only current way.

[toolbelt]

Have you noted 'The Brat' going in circles?  If so then it has run into high/thick grass and you should hear the motor ramp up.  It actually can handle some heavy grass before ramp-ping up.  I had a grass plant that grew about 3 feet high and from it the lawn got a lot of new plants.  Junior keeps them mowed down but when he runs in that area I can hear him ramp up.  But, at the same time he will go into his circle mode.

[AekaGSR]

Have you noted 'The Brat' going in circles?  If so then it has run into high/thick grass and you should hear the motor ramp up.  It actually can handle some heavy grass before ramp-ping up.  I had a grass plant that grew about 3 feet high and from it the lawn got a lot of new plants.  Junior keeps them mowed down but when he runs in that area I can hear him ramp up.  But, at the same time he will go into his circle mode.

Yes it goes into circle mode. No ramp up though.

[AekaGSR]

I decided to dip into the service menu.  There was a "high RPM" option and it was set to off.  I turned it on and now it ramps up in tall grass.  Why that was off is a giant mystery to me.

[RobotLady]

Good catch! 

I have heard of the high RPM setting in the service menu but never had a reason to play around with it.  Its purpose is to enable the robot to cut very thick grass that may have otherwise bogged down the blade. 

The downside of using the option is it will cut the run times short and that affects the maximum mowing area (hence the reason for making it an option).  In some older versions of the software it caused the blade motor to overheat, so users should not turn it on unless there is a true need for it.

I am really glad you found the reason for the lack of speed control and that it was just an improper user setting...

Cheers,

RobotLady

[AekaGSR]

Overheating a motor can go both was, especially when bogging one down.   Don't these have thermal sensors to stop the blade if they get hot?   Mine used to turn off from time for 30 seconds or so from time before I found the modulation.

[RobotLady]

Yes, there is a temperature sensor for the blade motor for sure, and maybe also the wheel motors.   The brushless models have a temp sensor on all motors, I believe.

The early software had bugs in it that allowed the motors to overheat.  Those issues have all been resolved as far as I know.