can i replace any battery(s) with any other battery(s) as long as the total voltage is the same?

9v are commonly used in a lot of projects, but 150mah give or take isn't a lot. since they're nothing but 6 aaaa and ohms law is v = ir, then couldn't u use 6 aa instead of a 9v for any project? also could u use different battery chemistries? i have no idea about that one because it would definitely change the overall esr and although most battery esr's are very low, i don't know what would happen if u changed it even a little.

AndyGadget8 years ago
If your equipment is expecting 9V, any combination of batteries adding up to that would do the job, but you'd want to keep the capacities and state of charge the same otherwise when one runs out before the others it will upset the whole circuit.
Batteries have different chemistries for different applications.  Some, such as lithium batteries are good for short bursts of high current and would be used in camera flashes etc.  Others may have a very long lifetime at low current and would be more suitable for fire-alarm type applications.
Also, some types will maintain a very steady voltage for most of their capacity, whereas others will slowly fall during their life.

mathews8 years ago
What circuit are you trying to make? If its that much of a current hog, you might want a mains power supply, or investigate higher power rechargeable batteries.

You can also get battery cases that allow for fast switching. Or consider building the recharging feature into your circuit.
Re-design8 years ago
If this piece of equipment uses rechargeable batteries and recharges in unit you will have to charge out of unit if you change the battery type.