So,on my 70 f250 I disconnected the battery, both terminals. Took out the battery to clean the tray. Put battery back in tried to start and all got was a click from the starter and lost all power, no lights, nothing, completely dead. Put battery on charger and the charger says it was charged. Figured maybe I have a bad battery. Took it in to get tested, test said it was ok. I got a new on anyway. Put it in. Starts great no issues. A day later go to start. Same issue. Starter tries to start, but not enough power and no lights again. Completely dead. I checked the ground on the block, cleaned it . No help. Checked connections. Put new battery on charger even though the charger says its charged. Not sure what I'm missing.
Blue, if you have power into the vehicle and everything works but the starter, you should start by cleaning up the terminals from the solenoid to the starter. The solenoid is the box on the fender where the battery cable connects.
If you do that and have no results come on back in and tell us your symptoms.
Clean and firmly secure both ends of the battery cables (positive and negative). Also clean the battery posts to expose new metal.
Second, make sure the ground strap between the engine and the firewall is also clean and secure... a loose or missing ground between the cab and the engine creates all sorts of weird symptoms. Ask me how I know! .. One time my electric fuel pump cycled when I turned on the headlights!! After reconnecting that ground strap everything went back to "normal".
These old classic many people don't ever think of changing out the 40+ yr old battery cables. The old cables over time depending on your climate can corrode inside the insulation and build up of a green corrosions of resistances that cuts down the flow of voltage.
Once your cables have been removed and reattached is the main cause of a poor connections at the battery itself. Clean/ but best to replace all the three large battery cables to insure a good voltage flow of your vehicle.
Rear engine grounding strap is important needing to be good also.
The starter solenoid mounting screws should be tight also as they also secures a good grounding path.
And any of these could be your problem.
I agree and you can test your cable by putting a meter across them when the circuit is active. Put one end of the meter on the cable at the battery, then the other end of the meter on the other end of the cable. The meter will read the amount of voltage dropped across the cable when the circuit is active. It should be almost zero.