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resistor on the altinator?

suntiet

suntiet

New member
Hello, I am new to this forum, but have been messing with my AQ-120B for a few years now. I am not charging, pretty sure the regulator is toast, so i swapped in anothercomplete alternator that i have. Puts out next to nothing witht he resistor in line to the feild wire and 14 volts without the resistor. Does anyone know why it's there? How about a resistance measurement so i can test it?

If i have to replace alternator a i better off putting a one wire system on??

Thanks
 
The 1 wire Delco 10si is a good alternator, and is easy to install.

The engine RPM must be bumped/increased to initially excite the field.... but once excited, it will remain excited until shut down again.
 
If i did install a one wire, Do i just cut the other wires off and tie them out of the way and run the one wire straight to the starter where the main battery cables hook up? I don't have to worry about the rest of the wires?

Thanks again i have been thinking this was the way to go.
 
boatdoc55 said:
Exactly 100%
Click to expand...

I am not sure what it does. My batteries went dead on me this last weekend. Although I have it set up so that I have reserve capacity for three days so no worry. But I cruise prince William sound so I want my charging system to work right.
I get 12.2 volts with the resistor in place, which was my battery voltage, and 14.4 with out the resistor. And the motor turns off when I turned the key off.
How do I test to see that my charging system is working right?
Am I better off installing a one wire system?
And if I do what do I do with the existing wires if I do?

thanks
 
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OK I tested the resistor in both directions. 69.7 either way. I am going to try the new alternator again tonight after work. I will take voltage readings at all the points to see, both with the engine running and with it off. Does anyone have any other ideas of how i can test weather the alternator is putting out?

Thanks again for all the help/knowledge.
 
Volvo Penta calls this a resistor.
Kim is correct. It's actually a diode as to prevent the alternator field circuit from back-feeding to the ignition circuit... of which feeds the field circuit.

Some of the early V/P engines would not shut down due to this.

.
 
.......................

suntiet said:
My batteries went dead on me this last weekend.
You'll need to learn why and correct the problem.

Question.... are you not turning your MBSS to the OFF position when you leave the boat unattended?


I get 12.2 volts with the resistor in place, which was my battery voltage, and 14.4 with out the resistor. And the motor turns off when I turned the key off.
How do I test to see that my charging system is working right?
Place you VOM directly on the battery bank that is currently being selected via your MBSS.


Am I better off installing a one wire system?
Your call... but they do work well.

The 1 wire 10si is actually a 2 wire.
You'll have the Charge lead terminal, and you'll have the Chasis Negative wire terminal.

And if I do what do I do with the existing wires if I do?
See above.
Any circuits not being used can be properly capped off.
Click to expand...
 
I just went through and checked all the wires. I leave the battery switch set to battery one most of the time, and i fully trickle charge the batteries before each trip. The only items that are left on for overnight trips are the anchor light, and the small Garmin GPS/fish finder (which i turn the display dark) for the anchor drag alarm. And maybe charging a phone. The Furno fuel flow meter also stays on as well. Not sure how many amp hours of draw it is. The Number 1 battery went dead enough not to start on the morning of the third day. We ran a couple hours every day at least. I am 95% positive the alternator was the problem. I installed my spare alternator when i got home and just want to make sure it's working properly. The only high draw electrical I use is an Ace line haul pot puller and maybe an endurance capstan for the anchor (which isn't installed yet) This same motor setup worked great in my last boat with the capstan and same electronics. ( I mean the exact same setup i took it all out of one boat and put it in this boat last year)

When i get home tonight I will check and see again if it's good by measuring voltage with engine running and off. I am just overly nervous and want to be as prepared as i can be on the water. I wish i could just shut the battery switch off to see that the alternator is working but i know i can't do this cuz it will ruin the regulator. Either way i am going to haul a spare battery around on my next couple trips just to be safe.

The real reason I am thinking of the one wire setup is it has more amps than the one i have now, not sure if i need them but a faster recharge after pulling anchor or shrimp pots would be a plus.

I just ordered an Ammeter to install between the batteries and everything else so i will know for sure which way the juice is going.

Thanks for all the advice/knowledge. I will post my voltage findings after work tonight.
 
Ok I had a chance to run it tonight.
12.9 volts before i start it
12.9 volts running at idle, 12.9 volts running at 1600RPM, 12.9 volts @ 2000 rpm.
I turned it off, took out the resistor (since it measures both ways i assume it's not a diode)
14.2 volts at idle, 14.2 volts at 1600 rpm and 14.2 volts at 2000 rpm.

I am now worried that it is either not working with the resistor in place or it is and just not putting out any juice, or if i run no resistor i am going to fry my system because it is too much????

I don't have an ammeter to hook up yet. when it gets here i think i am going to wire it to show total amp flow on the battery and not just on the alternator.

Any ideas?

thanks.
 
i cant figure out how to post pictures. As soon as i do I will.

There is one big oragne wire off the + post
one black wire off the - post
one ground wire
and the purple wire with the resistor.
 
I am trying to find out if i am discharging or not. I wasn't charging all last trip. Changed out the alternator and the old resister fell apart in my hands. So i installed the alternator and resistor off my old spare set (that worked in that boat) and am trying to figure out if they are working or not.

And none of my schematics have it either. But there was a resistor on both boats i've owned with this motor in it???
 
kimcrwbr1 said:
........... Anyway at around 1500 - 2000 rpms you should get between 13.9 and 14.7 volts at the battery. There is a procedure to test the amp output of the alternator you hook a ammeter between the alternator batt terminal and the battery charge wire.
1.... Pull the coil wire off of the distributor cap and short it to ground.

2.... Crank on the starter for 15 seconds to discharge the battery some then hook the coil up and start it and run it up to 2000 rpms quickly it should be putting out 32 amps minimum.
Click to expand...
Kim, great info and well said. :)

1.... As per Kim, the high tension lead must take the spark to Negative... otherwise coil damage may occur.
Or..... disconnect the power lead to the ignition coil and don't bother with the high tension lead.

2.... Checking alternator output in terms of amps does require that the battery be down a bit... otherwise, the regulator cuts back (as it should) and we won't see much in terms of amp output.
 
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