Battery power in home tools is critical. Remember those first power drills screwdrivers. They could barely turn themselves much less a screw. There's nothing worse than being in the middle of a home project and have your cordless drill crap out. The worst offender for premature wimping out are cordless vacs, namely the Black & Decker DustBuster. I have two 7.2 volt DustBusters and they a both don't suck, BUT THEY"RE SUPPOSED TO!!! I get two minutes max of sufficient power to make using them worthwhile. In other words, I get about a third of my car done of my car before the &^%#%@) unit dies. The earlier 4.8 volt DustBuster was useless junk and the 7.2 volt units didn't improve on it much. Somehow the 7.2 volt unit earned three and half stars in Amazon reviews…maybe I got two lemons. Black & Decker has a huge line of corded and cordless portable vacs. In cordless, they come in many voltages now: 9.6, 14.4, 15.6 and 18 volts. The 18 volt PHV1800 gets four and a half stars on Amazon's user reviews, but costs $55 while less energized units are consider less.
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