It’s supposed to last 40 minutes, when fully charged, but I asked it to work very hard and it barely made half an hour
It’s back on charge again and should be ready for duty this afternoon
I am also moved by all I am seeing and reading and hearing about the BLM movement and attach a link to three minutes from the Reverend Al Sharpton’s eulogy yesterday at the memorial service for George Floyd
gfreedmanblog 
I think you are pushing your luck with the strimmer! The task set seems more appropriate for a heavy duty hover mower.