So I got this boombox with the intention of powering it with li-ion batteries. 18650 batteries are 3.7v (average), so 3 in series supply 11.1v (average). I used 3 in series, 2 in parallel to get 5200 mah, and 11.1v. Fully charged, this pack is at 12.2v, slightly above 8 1.5v alkaline batteries. The drop off is far less, and averages more over it's life as well.
As you can see, both NIMH and alkalines average about 1.2v over their life, and cutoff at about 1v, so an 8 cell boombox is getting 12 to 8v, averaging 9.6v.
3 3.7v li-ion batteries fully charged were at 12.2 v, and it should average 11.1v over its life, with a dropoff around 10v, so it should give a little more power. Here is the box I ended up getting, a Panasonic RX-5050. It's a little rough. I got it off ebay. Skippy provided me with a missing slider
The batteries are slightly longer than a D-cell, so I cut a piece of wood slightly shorter than a D-cell as a spacer. I used the nippled end of a D-cell to contact the boombox circuitboard, and then had a wire going around to a nail on the other end. I then have a test lead with alligator clips on the other side to complete the circuit.
As you can see, both NIMH and alkalines average about 1.2v over their life, and cutoff at about 1v, so an 8 cell boombox is getting 12 to 8v, averaging 9.6v.
3 3.7v li-ion batteries fully charged were at 12.2 v, and it should average 11.1v over its life, with a dropoff around 10v, so it should give a little more power. Here is the box I ended up getting, a Panasonic RX-5050. It's a little rough. I got it off ebay. Skippy provided me with a missing slider
The batteries are slightly longer than a D-cell, so I cut a piece of wood slightly shorter than a D-cell as a spacer. I used the nippled end of a D-cell to contact the boombox circuitboard, and then had a wire going around to a nail on the other end. I then have a test lead with alligator clips on the other side to complete the circuit.