It wants 2 die when I put the lights on or.

Check the charging system a good battery need a good charging system. You have a 12 volt battery. The job for the alternator is to keep the voltage stable. So at a running condition you will have 2 volts above battery voltage. Either the alternator has a weak out put, or the vehicle body and engine ground has high resistance or bad connections

Just to add, what motor do you have as it may not be keeping a good idle under load

Roy