After having an electric hedge trimmer for a couple of years in houses with minimal landscaping requiring trimming, we moved into our current house. Now we were proud owners of bushes flanking our garage on each side, a row of bushes between our house and our neighbor's house, jasmine growing up our house by the front door, jasmine growing up our walls in the backyard, and an entire block wall covered with ivy. Needless to say, a corded hedge trimmer just wasn't going to cut it anymore (so to speak).
Another large factor in our upgrade to a battery operated hedge trimmer is the fact that 90% of our backyard is a pool, which is located in front of the wall of ivy, so to cut the ivy, the cord would be hanging over the pool. Never a good idea in my opinion, to have a long extension cord hanging over and possibly in water. So off to Home Depot hubby went.
He selected the Black & Decker 18v Hedgehog trimmer. The cutting blades are about 22" long and the unit weighs about 7 pounds. Like most power gardening equipment I've worked with, there is a safety mechanism to turn it on, you have to pull back a toggle button and squeeze the trigger to activate the hedge trimmer. The blades will move/cut as long as you have the trigger squeezed, and if for any reason you let go with your hand, the trimmer will stop. Sometimes, if your hand just gives out as mine will do after a while, you can re-squeeze the trigger and it'll keep going (without having to slide back the toggle button), so this is helpful. There is also a plastic shield at the end of the blade, which I suppose is to keep leaves or small sticks from flying up and getting in your face. It must work because I've never gotten hit with any stray bush or ivy leaves!
If you're going to be doing a lot of trimming, this unit does get quite heavy by the end of your gardening session, but if you keep up with it and just do maintenance trimming once a month or so, it's not too bad. The charge on the battery is really good, it will last through at least an hour or two of trimming, I haven't ever had it die on me in the middle of yard work, and I charge it every time after I'm done, so I'm not sure how long the battery would last if I were to keep using it without charging it. The other nice thing about this trimmer is that it doesn't vibrate too much - I'm very sensitive to vibrations and my hands will swell up if there's a lot of vibration (I don't know why, they just do!) and I can use this trimmer and get everything tidied up without aggravating my hands at all. It is kinda noisy, so if you're planning on carrying on a conversation with someone while you're trimming, you'll have to yell a bit.
We've never had an issue with dull blades, I'm not sure if you can even sharpen the blade, or if it'd be just as cost effective to buy a new trimmer. We've had it for about 3 years, so I think that's excellent that the blades are still sharp and do a great job of trimming.
If we were to replace this trimmer, I'd definitely want to go with another Black and Decker cordless - they're great!