Ryobi brushless angle grinder spins and stops

Mortoney · Post by **Mortoney** » Mon May 17, 2021 11:08 am

I have purchased used brushless angle grinder from auction. It does spin for 1-2 seconds and stops. Also if you try to start again, it just shutters but no longer spin at all, then if you spin it manually with hand a bit, and then try to start again, it will run again for two seconds.
I have tried 3 different batteries, 1.5ah, 4ah, and 5ah.

Any ideas?

dewaltdisney · Post by **dewaltdisney** » Mon May 17, 2021 11:29 am

Yes, buy a new corded one off eBay for £20.

DWD

big-all · Post by **big-all** » Mon May 17, 2021 11:52 am

with the battery out when you spin the blade by hand does it feel rough or smooth is the noise different to the usual rhythmic drrrrrr ??

Mortoney · Post by **Mortoney** » Mon May 17, 2021 11:56 am

big-all wrote: ↑Mon May 17, 2021 11:52 am with the battery out can you spin the blade by hand ??

No blade installed at the time of testing, but i can turn the part/bolt where blade attaches, yes. When i turn it i feel it segment probably because of magnets.

big-all · Post by **big-all** » Mon May 17, 2021 12:04 pm

because its right angle drive you have a bit off surface slip on the gears hence the rythmic noise and feel
you shouldnt have any real resistance from the magnet as the metal core has no inbuilt magnetic force but off course is metal
how was it described on i assume ebay ??

Mortoney · Post by **Mortoney** » Mon May 17, 2021 12:33 pm

I have taken apart it earlier to see if anything physically stops it. Gear and the angle driver itself in close to new condition, pretty much no signs of use. Magnets seem to be in the motor itself because it is brushless motor, if i am not wrong

Mortoney · Post by **Mortoney** » Mon May 17, 2021 12:34 pm

I will go to b and q to see how it should feel when spinning manually when new

big-all · Post by **big-all** » Mon May 17, 2021 1:55 pm

in dc motors its a stator [stationery bit]]and rotor[rotating bit] with the rotor being the coil and the stator being the magnet making a permanent field
with a brush less now being possible because you can now get a magnet powerful enough to push against in the small space available in a rotor you dont need brushes to transfer power to the coils on the rotor as its now a non-powered permanent magnet pushing against the power off the outer [stator]coils powered by the battery

kellys_eye · Post by **kellys_eye** » Mon May 17, 2021 5:36 pm

Brushless devices require electronic control circuitry to enable them to work and as part of the circuitry there is current monitoring which stops the unit working under stall or overload conditions but, if the circuitry is dodgy, it can kick in and do as it's doing.

If the battery is under charged then a higher current flows and this can be 'seen' as a stall/overload and the protection kicks in - again.

So although brushless ones are potentially more powerful etc they have the disadvantage of added complication which, if it works correctly keeps the device and user from harm but if it goes wrong there's often little the average person can do to fix it.

The older versions, however, have a plug, wire, switch and motor (brushes) and if something goes wrong you can usually fix it - easily.