It's a 1997 GMC Yukon 5.7 liter engine 4 wheel drive
Hi Scotty, if a car is just running off the battery( alternator not charging the battery) how long on a standard 12 volt battery can it last with the heater and lights on. Thank you Rob
What kind of car? The modules in a modern computer-controlled car will start going funny in the head pretty quickly as voltage drops. An ancient vehicle with ignition points and carburetor might run for quite a while that way.
This is about the battery condition
not very long. And it will damage the battery.
A low battery can cause anything to go crazy. A bad alternator is worse. It can not only make the battery leave you stranded, it can overcharge your battery. Case in point: My parents had a 1992 Chrysler New Yorker 5th Avenue. The switch in the glove box broke where the light would not turn off. It not only kept running the battery down, it also made the alternator work overtime trying to keep the battery charged and everything inside the alternator melted together. Not only replace the alternator but make sure to check to make sure something is not staying on or shorting out and putting a parasitic draw on the battery otherwise you may be in this same predicament almost immediately after you change it.
well it's not discharging unless it goes below 12.7V
Double check all the electrical connections. battery, alternator, etc. make sure they're clean and tight. A 26yo car is could have some grounding issues going on as well.
I changed the battety and all the craziness except for the catalyst not working properly went awa t. Check engine light comes and goes.
@nancydrew1 if you have a question or need help, please create a new topic.
Scotty shares his experience and says watch the temperature gauge at 4:11
https://youtu.be/2psM35Y3Zj4?si=RZkslr1MhMOXlW3f
Hi Scotty, I have a 1997 GMC Yukon 5.7 liter engine with 236000 miles, I live in Oregon, last weekend it was colder than usual outside, I ended up with a dead battery, got it tested and it wouldn't hold a charge. It was 4 years old. Got a new one and had my alternator checked at two different places, the regulator, diodes and alternator all tested good but the gauge in the dash would show occasional discharge, normal and a slight charge is that normal. Thank you
but the gauge in the dash would show occasional discharge
what does that mean exactly? The needle is going below 12V? Did you verify with a meter?
I meant it was occasionally going under 14 volts. No I didn't check it, that's what the two different people at two different auto parts store told me when they checked it with their machines
When an alternator is charging it often can run around 13.5 volts, depending on the vehicle, when the power draw is not high. It can go as high as about 14.5.