Earlier this month, a plug-in hybrid caught on fire. In May, another one had suffered a "meltdown" of the battery pack. In both cases, no one was hurt. But some advocates of the technology are worried that, because of the incidents, plug-ins will get a bad name, and potential buyers will steer clear.

They shouldn't be worried.

Plug-in hybrids are like ordinary hybrids, but they have bigger battery packs that can be recharged by plugging them in. That gives cars extended electric range compared with conventional hybrids, which cuts down on gas consumption.

Plug-ins are all the rage these days with politicians and automakers, in whose minds they have apparently supplanted hydrogen fuel-cell vehicles as the cars of the future. It seems unlikely that the recent incidents will do much to change this. Both cars were aftermarket conversions of conventional hybrids. Cars designed from the ground up as plug-in hybrids aren't available yet. So the incidents throw into question the skill of those who did the conversions; the incidents don't suggest that plug-in hybrids are, in principle, a bad idea.

There might have been more cause for concern if the fire were the result of the battery cells. One of the conversions reportedly used battery cells from a company enlisted to supply batteries for plug-in hybrids from GM. It wouldn't look good if the batteries that GM intends to use started going up in flames.

But apparently, the batteries weren't the problem in either case. The fire and meltdown seem to have been caused by the electronics used in the conversions. One hopes that offerings from major auto companies will be better put together.

Right now, GM engineers are rushing to develop the GM Volt, a type of plug-in hybrid that's supposed to be available by the end of 2010. If those start bursting into flames after they roll off the assembly line, that would indeed be bad news for the future of plug-in hybrids.