Honda BF8A 8HP Charging Port... Short?

Doolin

Seaman
Joined
May 22, 2009
Messages
67
Hey there,

I recently purchased a 1997 BF8A and really liked the idea of having the ability to charge my battery. When I got it home I found the plug to be cracked so I replaced that. My boat (also a recent purchase) had a charging port wired to the stern so I found the mating plug, purchased the plug that mates to the motor and wired the two together with some 10 gauge.

I'm a coward when it comes to electricity... so, I started by testing the wire I made and I got the continuity where I expected it. I plugged in the wire to the outboard and the 'stern plug'. On the inside of the stern socket, I connected the positive to the battery.

Before connecting the negative to the battery, I took a test light, connected one end to the battery and touched the lead of the tester to the negative wire from the socket. The tester lit up solid.

I wasn't expecting that. It makes me think there is a short somewhere.

Is anyone familar enough with that charging system to confirm that there 'should not be' a complete circuit when the outboard isn't running?


Thanks in advance,
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Honda BF8A 8HP Charging Port... Short?

Let's get some terminology straight first. A continuity test is conducted on a single length of wire for example and in that example, the tester would need it's own battery to provide a current source. Current flows from the probe through the wire, and then to the ground clip. The light goes on to signify continuity. A circuit tester is a similar device but has no internal battery. It is simply a light bulb with two wires. This device is typically used to follow voltage around a circuit. It can't check ground because there is no internal power source. So I feel what you have done is used the test light to "complete" a circuit -- not test it. If I understand your test, current flows from the positive terminal of the battery, through the rectifier/regulator, out the ground path, through the test light to the negative terminal of the battery. That is a complete circuit and the test light would light. That does not signify a short. It signifies a complete circuit. You would get the same result if you connected both the pos and neg ends of the stern harness to the battery and then used the test light across the plug terminals. The light would light because you completed the circuit -- not because there was a short.
 

seabob4

Lieutenant Commander
Joined
Jun 10, 2008
Messages
1,603
Re: Honda BF8A 8HP Charging Port... Short?

Doolin,
You might want to check out this thread. It will take a lot of the "fear" out about dealing with electricity...

12 Volt Bible for Boats:)
 

Doolin

Seaman
Joined
May 22, 2009
Messages
67
Re: Honda BF8A 8HP Charging Port... Short?

I guess I did leave a bit of the detail out.

For the continuity test, I did use a multi-tester that does have it's own battery. I used that to test the wire I made (which I did initially have wrong... I was using 2 of the 3 prongs on the stern end of the plug and had one wire in the wrong spot). When I was done, I had what I expected from the wire I made.

For the 'circuit test' I did us the unpowered test light.

I don't understand the internal workings of the outboard that 'do' the charging. I did not anticipate there to be a 'completed circuit' though. When the light lit up... that indicated that current was flowing. Not only would there be a spark when I tried to connect the negative but current would flow until the battery was dead... at least that's my understanding.

Since it wasn't what I expected... I figured I'd ask someone who does know.

If... for example... the stern socket (which I didn't wire) was shorting from the positive wire to the negative... that would cause a complete circuit the way I tested... had I hooked the negative wire up like that... the wires would have smoked and caught fire (done that one before).

So, if having a complete circuit is correct and causes no current draw... the test light lighting seems to indicate current flow, then I should be ok to hook up that negative wire.

I just don't want smoke, fire or a dead battery.

And yes... I'll go check out that link.

Thanks.
 

seabob4

Lieutenant Commander
Joined
Jun 10, 2008
Messages
1,603
Re: Honda BF8A 8HP Charging Port... Short?

Doolin,
Keep this concept in mind. A 12V system is basically a circle. Battery to appliance, then back to battery. Both hot and ground are hooked to the appliance, whether it be a pump, light, whatever, and it works. So, you say, why can't I just remove the appliance, attach hot and ground, and complete the circle? Well, the appliance uses power, which decreases both your voltage and your amperage on the "return" side. You need a "consumer" in between to make the system work...
 

Doolin

Seaman
Joined
May 22, 2009
Messages
67
Re: Honda BF8A 8HP Charging Port... Short?

Doolin,
Keep this concept in mind. A 12V system is basically a circle. Battery to appliance, then back to battery. Both hot and ground are hooked to the appliance, whether it be a pump, light, whatever, and it works. So, you say, why can't I just remove the appliance, attach hot and ground, and complete the circle? Well, the appliance uses power, which decreases both your voltage and your amperage on the "return" side. You need a "consumer" in between to make the system work...

Does this have something to do with my queston? If so, I missed it. I'm familiar with the concepts of Direct Current, Alternating Current, Voltage, Amperage and DC Circuits.

I'm not familiar with the DC Charging Port on the Honda Outboards.

Again, the motor has a positive and negative lead to charge a battery. Connecting the positive to the battery terminal, the negative to the test light which is connected to the battery negative terminal will show if there is a complete circuit with the outboard off.

Since the test light lights up... the circuit is complete and power is flowing through the test light... lighting it up.

So, if I removed the test light and connected the negative wire... I'd expect that current would continue to flow until the source was depleted.

If this isn't the case... I was hoping someone could explain the difference.
 

seabob4

Lieutenant Commander
Joined
Jun 10, 2008
Messages
1,603
Re: Honda BF8A 8HP Charging Port... Short?

So, if I removed the test light and connected the negative wire... I'd expect that current would continue to flow until the source was depleted.

You are correct, sir. But the motor must be running for the alternator to output charging amps. You may have voltage present at rest, but what exactly are you trying to determine? That you have charging amperage? That you have a complete circuit?

Just went back and read your OP. At rest, which is with the engine off, youi may have voltage in the circuit, which indicates that you have a "connection". When your engine is running, the alternator is putting amps back into your batt, which is a different measurement than voltage...:)
 

Doolin

Seaman
Joined
May 22, 2009
Messages
67
Re: Honda BF8A 8HP Charging Port... Short?

You are correct, sir. But the motor must be running for the alternator to output charging amps. You may have voltage present at rest, but what exactly are you trying to determine? That you have charging amperage? That you have a complete circuit?

Just went back and read your OP. At rest, which is with the engine off, youi may have voltage in the circuit, which indicates that you have a "connection". When your engine is running, the alternator is putting amps back into your batt, which is a different measurement than voltage...:)

I wasn't testing for voltage with the test light. A test light won't test voltage. I was checking to see if current was flowing from positive to negative.

I've used that particular test to check for current draw when everything should be off. I had a small draw that would drain my battery if I left it connected.

It's also a good way to avoid huge sparks when you accidentally wire something wrong. You shouldn't be making sparks when you connect your battery.

So by putting the test light between the negative battery terminal post and the disconnected negative cable from the outboard, I got the test light to light up.

That is an indication of current flow from the positive battery terminal post, to the negative battery terminal post. That current flow (and the light won't tell me how many amps... i.e. if I'd be arc welding by touching that wire to the negative post) will eventually drain the battery if left connected.

If there was a short in the circuit... i.e. cables crossed prior to reaching the outboard, connecting the cable would be a direct positive to negative connection on the battery. Lots of sparks and the wire would heat to bright red, smoke and catch fire.

Also, I did test the output of the outboard... it doesn't push much. At idle it only pushes 1 volt.

So, still I'm looking for someone that can tell me if current should be free flowing through an 'off' outboard charging port?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Honda BF8A 8HP Charging Port... Short?

Since when does a test light NOT test voltage. Again -- your test light is nothing more than a light bulb with two wires. Connecting it directly across the battery terminals lights the light because you have COMPLETED the circuit. When you insert the tester in the ground lead you are placing it in SERIES with other components in the charging system such as the rectifier which converts the AC power from the stator on the engine to DC. Again, in this appication you are completing the circuit. This is NOT the tool to use to perform the test you want to perform. You are looking for shorts an ohm meter is the tool to use. Disconnect both the engine/stern cable plug and the wires at the battery. Set the meter to ohms x1 and touch the probes across either the plug terminals or the other end of the wires. A reading of infinity says OPEN circuit as you should expect. Any other reading says you have a short. A test light cannot do that as it is not "self powered". The next test is to connect the battery end of the stern harness. Set the meter to DC volts (or use your test light) and touch the probes across the pins in the stern harness plug. 12 volts (or light) says you have "continuity" and you have now proven that much of the circuit works. You then connect the motor/stern harness plug and fire the engine. Use the voltmeter (not your test light) to measure battery voltage with the engine at about 1500 rpm. Voltage should be in the 13.5 range or higher indicating the battery is being charged. If not -- it isn't and the stern harness has nothing to do with the problem. The issue is at the engine.
 

Doolin

Seaman
Joined
May 22, 2009
Messages
67
Re: Honda BF8A 8HP Charging Port... Short?

Since when does a test light NOT test voltage.

So, you hook up the test light and it comes on. How many volts is that?

Hmmm... my guess is you don't know because the test light doesn't test voltage (quantity anyway... existence of voltage maybe... but not what I was talking about).

I'll run through the tests you suggested... but I still don't have the answer I'm looking for.

That is... with the test I did do, my expectation is that if I hook up the negative battery cable... current will flow until the battery is dead.

My expectation is that you can hook up this motor with it off and it won't kill the battery (by allowing a free flow of current). That wouldn't make much sense.
 

Rdrider

Recruit
Joined
Aug 20, 2011
Messages
1
Re: Honda BF8A 8HP Charging Port... Short?

This reply may be a little late but it might help someone with a similar problem.

Put your multimeter in series with the circuit to test amperage draw (in place of the test light).

Set the meter to 10A, put the red lead on the meter in the 10A socket. Connect other end of red lead to outboard negative and black lead to battery negative. Make sure the positive is hooked up from battery to outboard. If you have done this correctly, there should be a low if any reading on your test meter. If there is a high reading (0.1A +) then you have a parasitic draw on the battery which means possible drained battery/short circuit.

When you hooked up the test light you CREATED the draw on the battery.

If the meter showed little or no amperage draw, then you should have no problems with a drained battery while the circuit is connected (considering your battery is in good order).
 
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