mighty max charging? low power.

[Gsprusty]

My 91 mighty max 4 cyl. New Battery and alternator ? Ran good for about a day after both changed. Lost power from the drive back home from work. Any suggestions trouble shooting would be appreciated. Lights were dimming on the way home, no radio. Backfire up a Hill. Would sit and idle once home shut off and now starter clicks going to charge while I sleep. Thanks for help.
My 91 mighty max 4 cyl. New Battery and alternator ? Ran good for about a day after both changed. Lost power from the drive back home from work. Any suggestions trouble shooting would be appreciated. Lights were dimming on the way home, no radio. Backfire up a Hill. Would sit and idle once home shut off and now starter clicks going to charge while I sleep. Thanks for help.

[geezer101]

First up you will need to know whether or not the alternator is actually charging - put a multi meter across the battery while the engine is running and you should be getting about 13.6 - 13.8v. If it's charging then you will have an accessory or something else draining the system. There could also be a bad ground lead issue somewhere. If the alternator isn't grounding properly into the charging system this will affect how the battery gets it's top up charge. Were you having a voltage/charging issue before you replaced the battery & alternator and did you change anything in the truck prior to the battery dying on you?

[Gsprusty]

Seems to lose power while driving. Just charged the battery. Ground seems good too. 13 volts while running at idle.

[Gsprusty]

Seems to lose power while driving. Just charged the battery. Ground seems good too. 13 volts while running at idle.

[geezer101]

It should be pushing more charge voltage than 13v. Seems like there is a drain somewhere on the system (IMO). Do you get a jump in voltage when you rev the engine?

[pennyman1]

could be a shorted diode in the alternator - that would cause the low voltage. One way to tell is to check the battery for AC voltage across the battery terminals - if there is a reading, it may be bad.

[Gsprusty]

voltage of 13 across the battery terminals and alternator. not sure when i rev it yet. will sit and idle all day. i was wondering voltage regulator ?

[geezer101]

The regulator is in the alternator (the diodes that pennyman1 mentioned). They did away with external regulators way back.