Topic: Bad alternator or shot battery?

[yotaismygame]

this is on a 87 4x4 22r. I left the radio on by accident and had to jump it when i came back out. Well i make it up the hill then it dies. So i take the battery home charge it to full come back no dice. Jump it turn the lights on it dies.

Shouldnt it run with a dead battery but good alternator?
and shouldnt it run with a bad alternator but good battery?

[miks85yota]

start it up and pull the neg cable off the battery, if it stays runnin ur alternater is good. all the battery does is start the truck, everything else runs off the alternator, . i have seen one stay runnin with the cable off, but the alt wasnt puttin out enough amps  needed to charge the battery.i just went through the same thing type problem with my runner and had a few bad grounds on the body and frame, u can try that, kinda sounds like a battery dischargeing.

[yotaismygame [OP]]

solved my problem. The first time i charged it, it barely had any water in it, the second time i i filled it up and its all good now, got my truck home. I was just confused why it didnt stay running once it was jumped, Ill have to test the alternator just to make sure thanks for the help.

[79coyotefrg]

alternator is on its way to a lonely grave

[junya92toy]

Sometimes even with a bad battery, it still wont run if you jump it. A cell can short and wont let any power through it.
 

[Cheesemaker]

Once you kill a battery, it will never be as good as it was before you killed it.  Unless you have a RV deep cycle as your main battery, and even then over charging a deep cycle will ruin it.  Heat and vibration is a batteries worst enemies.

Here is a little trick I had Kyota told me about, Marlin told him.  When the engine us running, take a piece of metal and touch the center on the back of the alternator.  It should be magnetized if the alternator is working good.  If not, alt. is bad.

[THE ROCK]

I hope you used distilled h2o and not tap water! The chlorine in the tap water aint no good for batteries!

[axled89]

good call.  it kills batteries