Having read all of the reviews I decided to go ahead and purchase the strimmer. Delivery was within48 hours. Assembly was straight forward, although the wording is very limited and a bit of trial and error is required to fit the guard. Once fitted it seemed very secure. I charged the battery overnight and used the strimmer to both strim and edge my lawns. It performed superbly. I ran the strimmer to battery exhaustion as recommended and recharged again overnight. I didn't use the strimmer again for four days. On the second usage I edged and strimmed both lawns and longer grass in my orchard around the soft fruit cages - the battery performed without notieable loss of power due to draining of charge - and ran the battery again to exhaustion. On both usages the line didn't tangle or fail to pay out. So far I am extremely pleased with the product and would recommend it fully.
As far as I can tell rapid usage of the plastic strim line may be due to the users causing the line to impact with stones, brickwork or similar. Grass is a very abrasive material and one should expect the line to be used. By following the manufacturer's recommended charge/use cycles I'm sure that the battery pack will perform to the manufacturer's declaration - 20 minutes of full power. 100% charge is not achieved until five cycles of use to full discharge have been undertaken. Follow the manufacturer's suggested procedures and problem free usage may well achieved. I look forward to using it regularly without having to uncoil and recoil many metres of cable.