PILOON
Super Star Member
Weak links can carry voltage but not amperage.
Have seen that more than once.
Happened to me recently on my water pump circuitry.
All readings, tests looked good but no water.
Changed all wiring, no joy.
Long and short was the wire at the CB was merely touching thus completing the circuit but would fail under load, in other words lightly spark welded.
Funny thing is it worked for over 10 years that way. Vibration or somethin similar caused the gap to open just enough, I guess.
Heck I had even re tightened all screws in my trouble shooting process.
LOL, my excuse is that the breaker location is such that the wire needed to be inserted blind, so to speak, and it was not under the screw but merely touching alongside.
Naturally the cure was found only after changing all wiring and having my pump professionally tested.
Live and learn!
But all's well that ends well!
I relate that episode hoping to explain as to why U get full voltage while not under load but no power to adequately spin the starter.
That is why battery load testers were developed.
Also saw this in aircraft we serviced.
Voltage OK but no power.
Caused by defective Circuit breaker.
CB's are miniature spring loaded devices that need a calibrated pressure to allow current. Weak /defective 'spring' allows voltage but not current.
In fact I would imagine that any CB that has been actuated a few times should no longer be considered reliable and or accurate.
Have seen that more than once.
Happened to me recently on my water pump circuitry.
All readings, tests looked good but no water.
Changed all wiring, no joy.
Long and short was the wire at the CB was merely touching thus completing the circuit but would fail under load, in other words lightly spark welded.
Funny thing is it worked for over 10 years that way. Vibration or somethin similar caused the gap to open just enough, I guess.
Heck I had even re tightened all screws in my trouble shooting process.
LOL, my excuse is that the breaker location is such that the wire needed to be inserted blind, so to speak, and it was not under the screw but merely touching alongside.
Naturally the cure was found only after changing all wiring and having my pump professionally tested.
Live and learn!
But all's well that ends well!
I relate that episode hoping to explain as to why U get full voltage while not under load but no power to adequately spin the starter.
That is why battery load testers were developed.
Also saw this in aircraft we serviced.
Voltage OK but no power.
Caused by defective Circuit breaker.
CB's are miniature spring loaded devices that need a calibrated pressure to allow current. Weak /defective 'spring' allows voltage but not current.
In fact I would imagine that any CB that has been actuated a few times should no longer be considered reliable and or accurate.