I have a Ryobi circular saw P501 when I put the battery it doesn't work...I don't use it to much....what happen battery are good because it work in my drill

https://diy.stackexchange.com/questions/187271/ryobi-circular-saw-motor-runs-blade-doesn-t

This may help you.

you have not described your problem with your device so i can not help you .
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need to replace battery(not holding charge

No but where did you buy it its a small saw mine works fine but its for limited use. You can't use it to cut frameing lumber but its handy.What have you done with it when was the last time you changed the blade ? Idon't know i have 5 or 6 differant skill saws differant blades differant uses its olny disigned to do so much

Try at eReplacementParts.com : Power Tool Parts and Tool Repair Diagrams.

If you need more help come back.Post / thumbs / testimonial are welcome!

Usually there is a button to press that locks the shaft arbor and then you use a wrench to tighten OFTEN is a left hand thread!

Check for lock button behind the blade guard toward the motor.

you need to pull back the lower guard (remove battery first) and then start the blade at a slight angle until it goes into upper guard and then put on the spindle and reinstall the flange and blade bolt and tighten bolt till snug. You might try Ryobitools.com for a users manual or call them direct at 1-800-525-2579 and have them email a manual to you.

After removing the blade bolt and the outer flange you will need to fully retract the lower guard (remove battery) and sometimes wiggle the blade but it will come out.

Yes you can, as long as the batteries are the same style and fit the older Ryobi tools. The Ah rating is a capacity rating. The higher the Ah, the longer the battery will last so the 1.7Ah will just last a bit longer than the 1.5Ah batteries, but yes you can use them on older 18v Ryobi tools. I do it all the time.

return it to Ryobi