Voltage drop

[Nanedsl]

Good evening from the south of France. I have carefully read all the very well made Red’s posts about white wire, wiring harness test, etc. But I couldn’t find an answer to my issue.

i bought a used DF70A from late 2011 for cheap, but not working. I bought a new marine battery (12v 100ah) + a new remote including new harness + a new white wire that I have connected from the battery + to the white wire plug (covered) on the remote harness.

When the key switch is off, I have 12,5v at the battery thick wires on the starter, in the fuse box, etc. As soon as I turn on the key switch or start, voltage drop to 5 or 4 or 3 volts... the same voltage drop happens when the key switch is off and I push the trim switch from the remote or from the motor.

Battery is fully charged, I have checked all fuses, tested both relay (165 & 170 Ohms), and cleaned all harness connections in the motor

The new analog Suzuki gauge that I bought do not turn on either (but lighting up shyly sometimes), I can’t hear the pump and no crank.

Any idea where the trouble would be from?

Thank you very much

[tsturm]

Good evening from the south of France. I have carefully read all the very well made Red’s posts about white wire, wiring harness test, etc. But I couldn’t find an answer to my issue.

i bought a used DF70A from late 2011 for cheap, but not working. I bought a new marine battery (12v 100ah) + a new remote including new harness + a new white wire that I have connected from the battery + to the white wire plug (covered) on the remote harness.

When the key switch is off, I have 12,5v at the battery thick wires on the starter, in the fuse box, etc. As soon as I turn on the key switch or start, voltage drop to 5 or 4 or 3 volts... the same voltage drop happens when the key switch is off and I push the trim switch from the remote or from the motor.

Battery is fully charged, I have checked all fuses, tested both relay (165 & 170 Ohms), and cleaned all harness connections in the motor

The new analog Suzuki gauge that I bought do not turn on either (but lighting up shyly sometimes), I can’t hear the pump and no crank.

Any idea where the trouble would be from?

Thank you very much

& hello from ALASKA!
First check the "new battery" with a load tester. Next check the + cable at the starter or solenoid (wherever it attaches next after the Batt.) Next ck the ground where it attaches to the motor (mine is on one of the starter mounting bolts) Something is loose somewhere if batt. is good.

[Nanedsl]

I have check these three points, and they are all of them at 12,5 volts when ignition switch is off. But as soon as I turn the key switch on, voltage drops to 5 or 4 or even 3 volts everywhere on the engine...

[tsturm]

I have check these three points, and they are all of them at 12,5 volts when ignition switch is off. But as soon as I turn the key switch on, voltage drops to 5 or 4 or even 3 volts everywhere on the engine...

LOAD TEST BATT???. Hook an inductive amp clamp over + cable at batt. & try to crank, amps up volts down = frozen starter? Seized engine? Can you turn the engine over by hand at flywheel? Any clicking noises when you turn s/w to crank? 12v to starter when turn s/w to crank?

[Nanedsl]

I’ll do the inductive amp clamp test tomorrow, but i’m Pretty sure battery is fine and I also tested with an other charged battery.

Starter worked fine when I took it off the engine and tested it straight from the battery.
Engine is not seized as the flywheel turn by hands and with the propeller as well.

no noise at all when I turn the key switch to start position and the voltage at the starter is between 3 to 5 volts.

So voltage is 12,5v on the two thick wires at the starter when key switch is off and 3 to 5 volts when turn on or turn to start. No voltage on the second smaller red cable of the starter in any position.

[tsturm]

I’ll do the inductive amp clamp test tomorrow, but i’m Pretty sure battery is fine and I also tested with an other charged battery.

Starter worked fine when I took it off the engine and tested it straight from the battery.
Engine is not seized as the flywheel turn by hands and with the propeller as well.

no noise at all when I turn the key switch to start position and the voltage at the starter is between 3 to 5 volts.

So voltage is 12,5v on the two thick wires at the starter when key switch is off and 3 to 5 volts when turn on or turn to start. No voltage on the second smaller red cable of the starter in any position.

"voltage is 12,5v on the two thick wires at the starter when key switch is off and 3 to 5 volts when turn on or turn to start"

If your battery LOAD TEST'S good then you have a loose or corroded connection some where.

Remember you can stack D-cell flashlight battery's together to get 12.5V but you aren't going to start your motor with it!

Good luck

[redlowrey]

I’ll do the inductive amp clamp test tomorrow, but i’m Pretty sure battery is fine and I also tested with an other charged battery.

Starter worked fine when I took it off the engine and tested it straight from the battery.
Engine is not seized as the flywheel turn by hands and with the propeller as well.

no noise at all when I turn the key switch to start position and the voltage at the starter is between 3 to 5 volts.

So voltage is 12,5v on the two thick wires at the starter when key switch is off and 3 to 5 volts when turn on or turn to start. No voltage on the second smaller red cable of the starter in any position.

The wiring in this engine is slightly different than the early engines, the two red cables at the starter, the thick cable main battery feed, the thinner one will go to your fuse box and is battery 30 amp feed for your trim relay and voltage regulator. The white feed wire you connected to the battery feeds the key and the fuse box as well, that is why you had some power at the fuse box.
If you have a charged battery and the main cable and ground is good you have to have +12 volts at the starter solenoid, check and make sure your isolator is not corroded and that is where your voltage drop is coming from.
Don't worry about anything else until you have sorted out the two red battery cables, and have battery voltage at the starter and at the thirty amp fuse at the fuse box.

[tsturm]

How did it turn out????

[Hydros]

I had trouble with my starter, kept adding batteries until we finally found a failed factory battery cable. See pics. Check resistance across your battery cables. Negative cable turned black and began coming apart under the insulation. Found it when it got warm while trying out new relays.20191129_152640.jpgAnyone know why this may have failed?

[Moonlighter]

All it takes for a main battery cable to fail is for water (especially salt water) to get into it.

How?

A tiny cut or pinhole in the cable insulation is enough to let water in, it then wicks along the cable.

A poorly done lug will also cause such issues.

[Hydros]

Thanks Moonlighter, the insulation looked good but I guess it might have had a pin hole. Factory cable assembly, cost a lot for a new one and the diagnosis time. They found it by luck when the cable heated up while looking for what we thought was a starter problem. Do you think the onboard battery charger was involved in any way. I always kill the positive connections with a battery switch. Always something!

[Moonlighter]

Thanks Moonlighter, the insulation looked good but I guess it might have had a pin hole. Factory cable assembly, cost a lot for a new one and the diagnosis time. They found it by luck when the cable heated up while looking for what we thought was a starter problem. Do you think the onboard battery charger was involved in any way. I always kill the positive connections with a battery switch. Always something!

Cant see what the charger could have done to cause internal corrosion in the cable. So no issue there.

If the cable was old, or often sitting in water eg in the bilge, or exposed to sunlight, its not uncommon to hear about internal corrosion. Google the wick effect in electrical cables and you will see how quickly it can happen. Copper wire corrodes very quickly in salt water too.

Simplest way to check without a ampmeter a is just to flex the cable around, if there is any crunchy feeling then its corroded.

[Nanedsl]

It was my main battery cables that failed !
redlowrey your advice to stay focus on sorting out the two red battery cables helped me a lot.
It now starts like a charm.thank you so much guys for your help.
Best regards