Originally Posted by
Sir Bikesalot
I was searching for a charger to do this exact thing and found this among others:
http://www.greenbatteries.com/unsmbachandc.html
Definitely not the only option. There are many smart charger options from other manufacturers--maha, etc.
I use that charger (re-branded as a Varta) and can say it works as advertised. I can charge different sized batteries at the same time and each has it's own smart charger circuit, so when a battery is full it cuts off the juice to that battery. All in all it's a quite good charger.