Low voltage when brakes wipers and heather used

[Street fighter]

I have a 73 dodge charger and for years I have put up with dim head lights at night when I hit the brakes or sitting at a stop light at night,just driving the voltage is at 14.5 but use the brakes, wipers or heater and it falls to 12.5 what can I do to get this problem solved?I run a hot wire off the battery to the alternator to see what it would do and it showed 15 volts on my gauge the voltage stays at 14 when I hit the brakes and with everything being used,but I worry that this may be too much voltage. what can I do to fix this 26 year old problem? I replaced all wiring going to the battery and the starter but it seem to be worst now. need help.

 

[HawkRod]

What you describe is normal operation for these old cars. The issue is with the alternator in that it is unable to put out sufficient current (amps) at low speed. Modern alternators not only put out more amps, but also do so at lower RPM. If you replace your alternator with a suitable replacement, the issue will go away.

CAUTION: Your old wiring system can probably handle about 45 amps. So just because you go out and buy a 100 amp alternator does not mean you can hook up tons of power hungry systems. The 100amp alternator will not hurt you unless you have non-stock loads that will draw a lot of power. If you do, then you should upgrade your wiring too. There has been extensive discussion on this topic, so a search should bring up some good threads...

Good Luck

 

[Icecobra]

Although the Alternator is a good start, the problem you discuss sounds like it could be the voltage regulator. You say you bypass it and you have plenty of voltage and the culprit would be the voltage regulator. You could test it and see how it goes, bypassing it will ultimately end in disaster since the battery can only handle the higher voltage for a limited period of time (30 mins to an hour). Then it overheats and things can start to go very bad very quickly. I would try to diagnose the problem and figure out exactly why you are having the problem then apply the proper fix. As stated be careful about the stock wiring and to much current draw if your having issues with replacing the alternator. I would check and verify all the grounds are good and clean and not creating any issue..