Hello everyone. First off I'm a rookie that inherited a truck from my dad just looking for some help so let's be nice ☺. Truck has low cranking speed and also excessive voltage drop during cranking. As soon as I hit the start button the voltage immediately drops below 10. I have cleaned all connections and changed batteries. Also if any help the starter sometimes sticks and will keep spinning even if I release the starter button. Any help will be appreciated I can give more info if needed also. Thanks
Where are you measuring the voltage? Check the cable ends, hot and ground, at the batteries and at the starter, for corrosion and/or broken wire strands. If one is hotter than the others after attempting to start, probably needs replaced. Replace the starter solenoid, or get a rebuilt starter, you don't want it sticking in. Have the batteries load tested if you haven't. Sounds like a shorted cell in a battery, they'll indicate okay no load but drop to nothing when loaded down. Each cell is roughly 2.3- 2.5 volts at full charge typically.
Thanks for the reply. I just really look at the voltmeter while cranking. No matter how strong the batteries are(I individually charged all three of them) as soon a I try to crank the gauge jumps all the way down. Correct me if I'm wrong but I read somewhere that if the starter solenoid is going bad or is bad it will pull too much while starting. Is that correct? Also should I take the batteries to maybe auto zone to have them load tested?
No, the solenoid only connects the batteries to the starter motor. While resistance in the solenoid contacts can cause a high draw, you would see a lot of heat and possibly smoke coming from it. Typical possibilities: bad batteries, bad connections, bad starter, engine dragging, combination of any or all. Charging batteries is no guarantee that they're good, you need to get them load tested. Anyplace that sells auto/truck batteries should be able to test them. Lacking that, get a decent voltmeter, put it across one battery's terminals (directly on the terminals, not the cable connection) and have someone try to start it. Do this for all three batteries, if the voltage at the battery terminals is less than about 12 volts you have weak batteries. If the voltage is decent here, do the same check at the starter, between the terminal on the solenoid where the battery cable attaches and there should be a battery ground cable on the starter also. If the voltage is good at the batteries but drops here, then you're down to a bad connection or probably bad brushes or a dragging armature in the starter.