KellyClarksonTV said:
Are there fuses around that are biased to blow when current runs one way rather
than the other? If so, they could be used in non-rechargeable batteries, so if
anyone tries to recharge one, the fuse will blow and disconnect the battery
terminals alltogether.
I have often seen Zener or avalanche diodes in circuits to protect
against excessive voltage spikes. The diodes are across the power
terminals such that they will only conduct if + and - are flipped.
The reverse-breakdown voltage of the diode is higher than the power
supply voltage, so they will conduct if high voltages are seen,
protecting the sensitive electronics. Additionally, if the power is
hooked up to the circuit in the wrong direction, the diodes will
conduct and prevent current from flowing the wrong direction through
critical components.
What you are describing could be implemented with a diode and a fuse,
assuming the diode can handle the current. I think it would be better
to make a "smart" battery charger that senses when the batteries are
put in backwards and refuses to charge them. It could sense the
existing voltage from the battery (even a dead battey should have a
small amount), and if it's negative, have a bit of logic that would
cut the power and flash the big red warning LED. I bet it could be
done with an op-amp and a transisor (or less, if you're clever?). I
don't know much about batteries, but I assume that if they go
negative, then they have serious internal issues... A battery that
dead would probably suck a lot of juice anyway.
Hope that helps.
-Ben
