1997 F150 alternator question

[deerefan]

I bought an inverter that plugs into the cig lighter from autozone and used it for the first time yesterday. I got in the truck this am and noticed my dash lights were dim and noticed the alternator not charging on the dash gauge where it normally does though it was still above the low warning line. Do inverters cause alt problems? First time i ever used one. How hard is it to change on this truck? It is a 4x4 with the 4.6.

 

[Soundguy]

did you leave it plugged in all night?

ultimately, the cig lighter plug is fuse protected at 20-25a in most vehicles, and loads under that range should be fine.

is there some other part of the story we might need to know in order to help us diagnose your issue?

depending on the wattage and duration, an inverter, a fairly power hungry and ineficient device can drain down a vehicle battery before you know it. most have a low voltage cutoff of around 10v.. but by then your vehicle battery is essentially 'discharged'.

i have seen quite low bats that still had enough umph to make a vehicle crank over and start up, only to cook the alt trying to charge that near dead load. alts are great at putting out rated load, but are not good 'dead battery' chargers. i always top low batteries off with a charger before subjecting an alternator to that kind of brute force load.

what else can you tell us?

soundguy

 

[deerefan]

No I unplugged it after i charged my laptop. I had the truck running while i was using it.

 

[brokenot]

Do inverters cause alt problems?

A smallish one that plugs into your lighter won't cause any alternator issues at all. I use two of them at work daily. The smaller one is rated at 175 watts, and the one in the second shop truck is rated at 400 watts.

I have the laptop plugged in constantly during the day....

 

[timswi]

I've used invertors many times in my truck and never had an issue...An over-draw would blow the fuse as was said prior.

Sounds like bad luck to me..Alternators just kinda go..Like a TV.