charging with lights on

[Madmaxx]

 i drove my cuda at night..and noticed that with the lights on the engine has to be at 1800 to be charging and not discharging?..is this normal for an old mopar?...the lights really dim down below that rpm..battery is newer..starts good cold and warmed up..can i put on the 70amp alt. to help this condition?.dashlights seem dim also..i move the reostat to max brightness but not real bright inside there..domelight is correct brightness tho!.thanks for the input!

[Bullitt-]

Hear this a lot & I experienced the headlight dimming at low RPM myself way back when. I cleaned/burnished every ground & charging contact under the hood I could find and the problem went away, also check that you have an engine to firewall ground strap seems those often get left off.
As for the dash lights the dimmer switch is problematic, some contact cleaner & working back and forth may improve things or track down member Slotts in the companies section & get one of his rebuilt switches.