Two ten feet long homemade test leads, made from very small telephone wire, allow you to test dc volts from source to load anywhere along the path. MC4 connectors get replaced with Andersons as they can be easily probed as seen above, while connected, and MC4s are difficult. A perfect circuit would measure 0 volts from end to end while conducting. Good luck finding one. The long, tiny test leads are easy to store.
After initial installation, with batteries getting all the amps that can be provided or accepted, a test lead on one wire at the charging device, and another on the same wire at the battery post/load (not the connector) will read the voltage drop due to resistance along that wire's length. Test both positive and negative current paths/wiring voltages. Sum them. Subtract that from the source voltage. Should equal the difference seen as testing with both probes while hustling from source to load taking measurements.
Trying to test voltage at one location, then scurrying to another, with a system that by design fluctuates, is frustrating. Connecting a long test lead at one end, then checking point-to-point and looking for increasing voltage with the other, can quickly locate a resistance/voltage loss issue from source to load.
Amps don't get enough credit. They do the work, and they cause symptoms to appear. Testing resistance with the very low current provided by an ohmmeter doesn't load the circuit, create heat and voltage losses. Fun exercise: Measure the resistance of a known voltage incandescent lamp bulb filament, and calculate amps and watts using Ohm's Law.
Anyone with dc charging systems should have a clip-on dc ammeter. They're now available for less than fifty bucks. Once baseline current readings become known through familiarity, reduced amps during known conditions is a first alert to possible connection/resistance problems.
After initial installation, with batteries getting all the amps that can be provided or accepted, a test lead on one wire at the charging device, and another on the same wire at the battery post/load (not the connector) will read the voltage drop due to resistance along that wire's length. Test both positive and negative current paths/wiring voltages. Sum them. Subtract that from the source voltage. Should equal the difference seen as testing with both probes while hustling from source to load taking measurements.
Trying to test voltage at one location, then scurrying to another, with a system that by design fluctuates, is frustrating. Connecting a long test lead at one end, then checking point-to-point and looking for increasing voltage with the other, can quickly locate a resistance/voltage loss issue from source to load.
Amps don't get enough credit. They do the work, and they cause symptoms to appear. Testing resistance with the very low current provided by an ohmmeter doesn't load the circuit, create heat and voltage losses. Fun exercise: Measure the resistance of a known voltage incandescent lamp bulb filament, and calculate amps and watts using Ohm's Law.
Anyone with dc charging systems should have a clip-on dc ammeter. They're now available for less than fifty bucks. Once baseline current readings become known through familiarity, reduced amps during known conditions is a first alert to possible connection/resistance problems.