Adrian15XXX
10+ year member
Senior VIP Member
I was wondering, i have a cap laying around in my garage, would that help reduce the dim? or should i just go with a new batt?
If you think a 90 amp factory alternator can keep 4 batteries fully charged, you're delusional. All that adding an extra battery does is allow you to be able to run longer with the car off. When the car is running, i.e. when the lights are dimming, the alternator that's having trouble keeping one battery charged has to work harder to keep another charged. That doesn't make any sense. Your system runs off of the battery, and usually, it drains it pretty quickly. Therefore, if the alternator cannot charge it fast enough, i.e. voltage drop, another can't help.My stock 90 amp alternator was able to charge 3 extra batteries fine....im sure his stock alternator could charge an extra yellow top. If not then he knows he needs a new alt. Besides its a lot better than a capacitor.