Well, after failing to get my old Craftsman chain saw running and using the little Ryobi chain saw my wife bought for trimming Crepe Myrtles, I can see the virtues of using a battery to power infrequently used equipment.
So, any rechargeable string weed eater that won't impress me with their utter feebleness? The Ryobi one get good reviews here- https://laguerrillagardening.o... and looks to use a replaceable pre-loaded spool instead of being re-fillable.

Look for the "usual suspects": Stihl, Husqvarna and Echo. You want a garden implement, not a toy masquerading as one.

Also don't be swayed by all those fancy trimmer heads: I've replaced a lot of them over the years (decades, really ) for friends, neighbors and relatives and they always manage to surprise me for how unfit for service they are. Those used on Bosch branded trimmers wouldn't look out of place in a Mattel playset.

I had many week trimmers and I have to say that I really like the BnD LST136B 40-Volt .
I have to say that it's all about the 40 volts. I've had a few 18v trimmers and I don't recommend them unless you have a very small space to work with. Another suggestion is to always have another battery.

If you are doing a large area or amount, i.e. doing it for an hour or more, don't waste money on a battery powered one, as a good one , with as liketogarden says, absolutely need at least a second battery, ends up costing far more than gas powered one.
I spent three hundred plus dollars repacking battery packs just for my drills this year and they do not need as much power as a trimmer does.

I have been using echo 58 volt for at least 2 years. My front yard is almost an acre, fenced, trees and bushes all over, brick edging around garden areas, and I use it in a proper 1300 sf garden for weeding. I use the 2 amp hour battery, as the 4 is too much and twice the weight. I do not kill the smaller 2ah battery. It has the other tools available, hedge trimmer and so on that is part of the echo PAS system. The 2ncd gen is out now. I would like one of them. I like the speed feed line loader. Run the line in the hole and wind it like a clock. My stihl fs85x is a pain in the ass compared to the echo 58v, but it is a midge lighter and has a broad shroud where the echo has a bikini shroud.