I just purchased a 2005 Srt 6 Roadster. Drove it home 600 miles. It has been driven every day since (last 4 days) This morning it started right up. After a short trip I got back in and would not turn over. All of the electronics are working. I hooked up a battery charger/starting unit to the battery and it started right up.

After driving around awhile I went home, same issue will not start unless hooked up to battery charger/starting unit. I figured bad battery and bought a new battery...Installed the new battery same issue, will not start unless hooked up to a charge/starting unit.

I saw the discussion about the solder joints on the RCM. Why would it start only when hooked up to a charging/starter unit even with a new battery.

Any advice?