# Robin 8.5HP Not Charging



## Lewie7 (Nov 27, 2014)

This is my first post so if I am doing anything wrong please tell me.
Robin EH25-2 Electric Start This is what I have checked: If I probe the disconnected charging coil running at higher RPM I read 44 Volts. I removed the rectifier and connected the AC side to a 24 Volt Doorbell transformer and read about 24 VDC so I assumed it was good. I have cleaned all connections.
I have discharged a new battery to 12 Volts not load. If I probe the battery with engine running at high RPM I get no change in the voltage


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## AVB (Nov 28, 2014)

From you description it sound like a loss ground between the rectifier and the battery. Try checking you rectifier output voltage using the case of the rectifier as ground reference with engine running at idle and the battery disconnected as to eliminate battery voltage feedback causing false readings. If the output voltage is there then you have a bad connection somewhere between the rectifier and the battery be it either in the positive or the ground circuit. 

In that it just matter of doing point to point checks until you where the voltage drops out. With the battery still disconnected and the engine check the rectifier case and the positive battery cable if the voltage is there then you definitely have a grounding problem. If the voltage is not there then check from the positive output of the rectifier and the battery negative cable. If the voltage is there then you have a problem in the positive path to the battery.

May this will help a little or did I just confused you?


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## Lewie7 (Nov 27, 2014)

Thanks That is logical. I will do the check (it will be next week) will let you know


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## Lewie7 (Nov 27, 2014)

Ok Here is what I have found this morning. If I disconnect the battery (-) I read 40+ volts DC everywhere I should. If I disconnect the Battery (+) I read 40 Volts DC. I do not find a place where the voltage drops. If I disconnect the charging coil and probe
I read the 40+ Volts AC. The ohm reading across the charging coil is 1.7 ohms and I get infinity either wire to ground. I noticed (after the check) one thing you said that I did not do (engine running at idle) I had the engine running at higher RPM when I made the checks. I am back where I started. I realize the voltage I am reading is open (no load). Could the coil be reading a voltage but producing very little or no current?


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## AVB (Nov 28, 2014)

According the engine wiring diagram this a very simple circuit to troubleshoot.

If coil was producing little or no current then the voltage would drop out as soon it is loaded. The resistance are perfectly normal as it is an isolated AC circuit. The voltage got to be dropping out somewhere before it get to the battery.



To bad your not close to me here in Elora, TN as I could've drop by. It hard to explain all of the checks that I would do as it is most experience related electrical checks that I have done for 30 yrs. These kinda of problems can drive you crazy.

Let's try something to bypass everything between the battery and that bridge rectifier. Take two long section wire. Run a ground from the engine ground to the battery negative terminal.; then run the other wire from rectifier output to the positive side of the battery and give it a test run. This way you can eliminate to engine charging if the battery is now receiving a charge voltage above it standby voltage.

Here is a link to the manual page for the EH25-2 in case you don't have the service or part manuals. Subaru Robin - Service and Support


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## Lewie7 (Nov 27, 2014)

Do I leave everything connected and run these jumper wires


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## Lewie7 (Nov 27, 2014)

Your Quote "If coil was producing little or no current then the voltage would drop out as soon it is loaded" I have had voltage probes on every possible location and terminal I have jumped grounds and hot (B+ wires)
The only time I have ever seen voltage (except from the battery) the circuit has been open
If I start the engine and remove the ground wire on the battery I see voltage. If I start the engine and remove the positive wire from the battery I see voltage.
I know just enough about electronics to be real dangerous. This thing has no regulator
just a full wave rec (is this correct?) The 40 Volts DC I see (circuit open) never appears anywhere when the battery is hooked up.


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## AVB (Nov 28, 2014)

Lewie7 said:


> Do I leave everything connected and run these jumper wires


It is probably safe to leave them connected but I like to isolate them for now. It a divide and conquer approach. 

Since it not charging currently I would just disconnect the wire going from the rectifier + output to the rest of the circuit for now and tie the new lead from the rectifier + output to the battery + terminal. This way we will find if the alternator and rectifier are definitely good or bad. If the battery starts charging then you will know there is a wiring problem that will need to traced down.


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## Lewie7 (Nov 27, 2014)

Can you tell me or reference me to help me understand how this "simple" system works. I am assuming that I should be getting 13.5 to 13.8 Volts DC minimum to charge a 12V wet cell battery. This system us unregulated; did the engineer design the max output of the alternator to never over charge the battery. How does the high voltage I am reading "open" (40+volts) reduce to 13.8 to 14.6 volts My motorcycle has a three phase alternator but the rectifier/regulator is smart enough to change with the load demands. the only thing this system does is recover the battery after a start up.


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## AVB (Nov 28, 2014)

Think of it as an AC to DC circuit. The alternator is the transformer's secondary winding. As voltage is fed the rectifier assemble which is a full wave bridge on this engine. This rectified output is a pulsing DC voltage so without an load the voltages are going to read close to peak valves. The battery provides the load and the internal resistance of the alternator, bridge rectifier and wiring provides the needed voltage drops. The alternator on this engine only provides a 1.3 amp charge current max so there will be a considerable drop from that open circuit voltage down to a more normal charging voltage.

Below is snapshot from the service manual of the engine electrical. The items outside the dotted box is the equipment provided wiring which can vary from this diagram. Also don't get confused and think the black wire in this diagram has 12 v on; it doesn't, it is a ground circuit for coil and applying 12v to it will destroy the ignition coil.


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