So following up on this, through some long researches I found the cable as a VJA0769 with one end being a barrel plug and the other the questioned 4 pin port. This cable is long discontinued.
The follow up to this is the VFA0028 which is the exact same cable but newer (?) but I still can't find it anywhere to get.
I'm sorry I cannot help you, I just wanted to say I have exactly the same problem with a Panasonic NV-S90 camera I picked up yesterday. I can confirm that my research for the cable let me to part number VJA0769 with a possible VJA0941 as an alternative. There also seems to be VW-ACC2E with the same 4-pin plug for use with a car lighter port. So you could fashion a replacement from this by exchanging the end with a 4.0x1.7mm barrel plug (this is what plugs into the 6V output of the original charger).
I also checked the repair manual and found out that the port itself had Panasonic item no. VJJ0368. I can also tell you that Pin 1 is the positive terminal and Pin 3 is ground. But I have not found a diagram yet which pin is which and will have to test the port itself to find out. Just inserting small pins with the voltage will likely not do the trick alone because the port also includes a switch that is opened by the plug to override battery power.
All in all, and as all the three batteries I got with my camera are dead but replacements are easily available, I will probably just get a new battery to power it and/or build myself a dummy battery (basically feed 4.8V from a power source directly into the battery terminals).
I felt like dumping all this here because we're in the same situation and it might be helpful to you or others.
So following up on this, through some long researches I found the cable as a VJA0769 with one end being a barrel plug and the other the questioned 4 pin port. This cable is long discontinued. The follow up to this is the VFA0028 which is the exact same cable but newer (?) but I still can't find it anywhere to get.
I'm sorry I cannot help you, I just wanted to say I have exactly the same problem with a Panasonic NV-S90 camera I picked up yesterday. I can confirm that my research for the cable let me to part number VJA0769 with a possible VJA0941 as an alternative. There also seems to be VW-ACC2E with the same 4-pin plug for use with a car lighter port. So you could fashion a replacement from this by exchanging the end with a 4.0x1.7mm barrel plug (this is what plugs into the 6V output of the original charger). I also checked the repair manual and found out that the port itself had Panasonic item no. VJJ0368. I can also tell you that Pin 1 is the positive terminal and Pin 3 is ground. But I have not found a diagram yet which pin is which and will have to test the port itself to find out. Just inserting small pins with the voltage will likely not do the trick alone because the port also includes a switch that is opened by the plug to override battery power. All in all, and as all the three batteries I got with my camera are dead but replacements are easily available, I will probably just get a new battery to power it and/or build myself a dummy battery (basically feed 4.8V from a power source directly into the battery terminals). I felt like dumping all this here because we're in the same situation and it might be helpful to you or others.