On a sunny day (Mon, 28 Sep 2009 10:08:54 -0400) it happened Phil Hobbs wrote in :
It's nice to warn people, but building something that refuses to do the
>job it's built for is poor engineering. (Of course our current plague
>of tort lawyers is partly responsible, but only partly.)
Well, I dunno, I have designed a charger like that (that would not charge below detecting a voltage that would require a reverse polarised cell to be in the circuit). Indeed you will often find that the battery (or cells) are really damaged if the voltage is that low. If you force charging anyways, then it will often not get to its full capacity. So, a red LED 'bad battery', with shutdown of the charge current, makes sense. For those who know what they are doing, those will find ways to charge it anyways. The reverse cell problem I have seen with NiMH in series, where once cell started leaking, and with sealed lead acid batteries where charging with a high voltage (charging a 12 V battery with say 16 V to get some current going), did not lead to any real capacity at all. Leaking batteries can cause a lot of damage.