Do I need a charging circuit if my power source outputs 9 volts and 2 amps?

I plan on using maybe 6 rechargeable 9 volt batteries in parallel to run some computer speakers I put into a cigar box and would like to charge them just by plugging the wall wart into the power source from the speakers. Does the need for a charging circuit change based on how much power comes in or is it necessary whenever you want to charge batteries?
Also if anyone wants to suggest a better battery setup, that's great. The speakers need 9 volts and ~4.5w.

Slowpoke7 years ago
Run 8 x 1.2 Volt AA (or C) NiCad batteries in series. This will give 9.6 Volts and heaps of current (and a lot cheaper than 9 Volt rechargable batteries). The additional 0.6Volts that is available would have no effect on your amp. Of course you will need to charge them. Charging would be done when the batteries are discharged (but not to 0 Volts).

This site gives you the basics on charging NiCad batteries;


They can also supply a suitable charger or you can build a suitable charger from some of the instructables here.
oddjobzombie (author)  Slowpoke7 years ago
Thanks for the info.
Do you happen to know if most battery holders are in series?
Most of the battery holders that take multiple batteries (same type) are connected in series. Just to clarify, you do need a special charger to charge NiCads or NiMh batteries. The 9 Volt power supply that you have for the speakers just won't do the job.
Agreed about using AA batteries - for the environment's sake up it to NiMh batteries though - significantly less toxic, better performance, cheaper and equally recyclable.