Yanmar Alternator Charge Lamp

[Pedro -Dawn-]

Originally Posted by Wotname

I see at least two issues with the this circuit but I don't have time ATM to have a detailed look - sorry.

1. The R wire has to go to the small +ve bus in the control panel as does the +ve side of charge lamp (LED).
2. There is a lack of fusing on a couple of wire - more info when I get more time to look further.

The general thrust of the circuit looks OK, just some detail to attend to

No worries!!!

About No. 1, HOLY!! thanks or finding that . I didn`t understand this from the original diagram from Yanmar, but now that you point it out seems clear hahaha.
Attached is a correction.

About No. 2, I didn`t consider the fuses in the drawings. So In the same attachment they go (the ones I think I should fuse):
- Battery to engine bay bus
- engine bay bus to ignition relay
- engine bay bus to starter B+
- Battery to Key Switch relay
- Key Switch relay to key switch bus

Not sure if I should fuse the senders/switches and/or Alternator R (will they affect the readings?).

[Pedro -Dawn-]

Originally Posted by Wotname

The 3GM (and 3GM30) uses a mechanical engine stop cable, nothing electrical about it unless a PO has modified the engine stop arrangement and added a stop solenoid. Even if so, I can't see how the alternator wiring could possibly affect an engine stop solenoid.

BTW, is the engine a 3GM or a 3GM30, not that it matters for the control panel?

Engine is 3GM30!!

No stop solenoid (it has a cable to stop the engine).

I think I am making a confusion about this diodes issue. Maybe I saw on schematic that used them in place of the original light switch? Either way, per your suggestion no diodes!

[Pedro -Dawn-]

Originally Posted by Wotname

4/0 seems overkill, even 2/0 might be overkill but I haven't run numbers ATM. The 3GM doesn't have a high starting current.

If you have to use large cables for a long run, mount a cable stud nearby the engine and terminate the large cable on this stud, then run a short smaller cable from the new stud to the starter motor solenoid.

I note you are connecting the alternator output direct to the house battery, again this certainly does not need a 4/0 cable. What alternator do you have?

The calc I did was:
- 1kW is 84A @12V
- Wire run is 4m one way

It is as you say,
- Voltage drop is 2.18% for a 1/0awg run

It does appear to be overkill. Thing is I already have a 4/0 excess from my winch wiring. But I could always save it for maintenance in the future..

[Pedro -Dawn-]

Originally Posted by Wotname

If you have to use large cables for a long run, mount a cable stud nearby the engine and terminate the large cable on this stud, then run a short smaller cable from the new stud to the starter motor solenoid.

I note you are connecting the alternator output direct to the house battery, again this certainly does not need a 4/0 cable. What alternator do you have?

Thanks for the tip on the stud!

The alternator is a stock Hitachi 55A.

I was thinking of future proofing this install though. To leave space for a higher output alternator in the future.

[Dalestr]

Most internally regulated alternators won’t stop charging if you turn off ignition switch with these engines running. Maybe that’s what your shutoff referred to. Be aware that as long as engine is running , you can’t safely ‘break’ the battery circuit.
The incandescent lamp used for Hitachi excitation is stated as 3W (or 250mA). With less current, like 150 mA, it will take some revs above idle before it excites. These lamps can last almost forever BTW as they get very little on time and even that is not at full 13V.
There are actually two excitation circuits, L and R for Hitachi from this era. This is totally unclear in the Yanmar shop manual as they clobbered the charging schematic badly. I had to redraw some of that to make proper sense.
R stands for ‘relay’ , a carry over term from the ancient electro-mechanical regulator days. This you just connect directly to IGN + to excite the Hitachi but no lamp warns you when the belt breaks and charge fault is not, I think, part of the horn circuit.
In any case, some folks at Catalina, who make their own panel, decided a charge lamp was foolish and deleted that critical warning circuit entirely and used instead the R circuit. Some Hitachi cloned 80A alternators were only designed for use with the L circuit and won’t awaken if the R circuit is used. Then you must rig your own lamp or resistor circuit as is well described above.

[Dalestr]

To be a bit more clear on the 2 excitation circuits, Yanmar drawings shows both in use. These are essentially parallel circuits, a belt and suspenders approach. Either can excite. The R circuit includes a resistor in the regulator to limit current to the field winding where the L circuit used the lamp for current limit.

[RaymondR]

Originally Posted by Wotname

In essence you electrically replace the existing incandescent charge light with a 47ohm, 5W resistor. Add a 12V* LED in parallel to the resistor to function as the charge light.

Mount resistor wherever convenient and mount the LED in the panel.



*A '12V' LED will have a suitable load resistor built into it however if you just use a 'raw' LED, you need to add a suitable load resistor in series with the LED. The value of the LED load resistor will be determined by the specs of the LED.

The series resister is actually a current limiting resister. Calculating for about 20 ma of current is usually about right for most 5 mm GP LEDs. The V in the E=IR equation is system volts minus the forward voltage of the LED, from memory about 1.5 volts.

Some regulators have a wattage limit for the indicator bulb. I use Bosch Universal alternators and usually wire a 100 ohm 5 watt resister into both the voltage sensing and initial excitation circuits to prevent excessive current into the initial excitation pin on the regulator. So the sum of the currents through both the LED and the parallel resister cannot be any more that that required to light a 5 watt bulb.