Just wanted to toss in some feedback, on the B&D 18v trimmers. I sold them at a hardware store, for over 2 years recently (not my store, just used to work there, in between electronics jobs).
For light to medium trimming, a lot of customers really liked them, once they learned the best way to deal with batteries. The basic black slide on charger is a manual type, no more than 8 hours for a charge - then disconnect it. A lamp timer works for well for this issue.
B&D has a full-auto 1 hour charger for these 18v batteries - this one you can leave these NiCd batteries on forever, as it automatically downshifts into a proper trickle charge, once the main charge is done. All NiCd batteries will self-discharge, for the customers that were irked by this, I always recommended leaving a battery in the auto-charger - the battery was always safe, and ready to go once the in-use one was down.
For heavy use, you need an industrial grade gas trimmer - I have a Stihl for my acreage. But, many folks are maintaining yards on rural properties that would put a few golf courses to shame - they rarely are doing the bush bashing type work that needs a heavy trimmer. Many folks came in, fed up fighting with gas trimmers (even brand new ones), and had 2-3 acres properties they wanted to trim. I sold many of these people a drill kit, in addition to the trimmer - just to get them a good package price on 2 extra batteries, and the one-hour auto charger - NOBODY ever came back complaining about lack of runtime - with 3 batteries and the auto-charger, that was plenty of trim time.
For light/med trimming, it is a good design, light weight, simple to use, charge the battery and you're good to go. In Canada, they have a 2 year warranty - some people would be back after 5-6 years to replace one they had worn out - parts are orderable, but often cheaper to buy a new unit on clearance.
No bump, the auto feed sytem is a good design. Long term, the only issues that sometimes come up are with the nylon toggle that controls the auto-feed: If it is reluctant to feed, just give the housing a good cleaning, as the toggle needs to be really free to move. After a lot of use, the numb on the end of the toggle may wear down enough that it is auto-feeding too much - a new toggle was something like $3, you just pop it out with a screwdriver to replace.
Even elderly ladies really liked the weight and balance of the 18v trimmer.
Good luck, on optimizing your seat time ! :thumbsup: Rgds, D.