Alternator Issues...

[Croxford]

I had problems with the alternator on my new 2YM15 engine so sent it back to Yanmar. The old alternator I borrowed whilst it was away work fine (although no rpm output as it was a different alternator design) through my split diode to my battery banks. Now I have refitted the alternator Yanmar repaired, it will not work through the split diode and will only work if I connect it directly to a battery bank (which I don't want to do). The diode could be faulty but I think it is unlikely given it was working until I changed alternators so all I can think is that I have wired it incorrectly. Any help would be appreciated... Thanks.

 

[Playtime]

I had problems with the alternator on my new 2YM15 engine so sent it back to Yanmar. The old alternator I borrowed whilst it was away work fine (although no rpm output as it was a different alternator design) through my split diode to my battery banks. Now I have refitted the alternator Yanmar repaired, it will not work through the split diode and will only work if I connect it directly to a battery bank (which I don't want to do). The diode could be faulty but I think it is unlikely given it was working until I changed alternators so all I can think is that I have wired it incorrectly. Any help would be appreciated... Thanks.

What make/model of alternator is it?

I think the problem is that the alternator needs an excitation voltage from the battery which it isn't getting because of the blocking diodes.

One solution would be to remove the diodes and replace with a VSR (cost around £60). This would provide a direct connection to one battery before the engine starts and then parallel the batteries when the charging voltage reaches 13.8V or thereabouts.

 

[VicS]

I was going to suggest a problem with the way in which the alternator gets its initial excitation.
But the diagram that I thought would explain it all doesn't!

Diag of Htachi alternator ( negative field regulation) below anyway in case it helps

P is the connection for the tacho, R is the initial excitation. L is the warning light connection.

You cannot get the initial excitation current backwards though the diode splitter if you see what I mean. It must come directly from a battery

I feel sure that must be the problem but without a diagram of your wiring cannot explain.

 

[Croxford]

Thanks for the replies. The alternator is the standard model supplied by Yanmar with the YM15 engine. The diagram has maybe opened up a lead... I used to use a Sterling regulator between the alternator and the diode (I did not wire this in this time as I believe this may have caused my initial alternator issues). I think the T connection is still connected to the Sterling regulator which is not connected to the battery. If this is where it is expecting the excitation from then we may have found the problem. Agreement or other views are very welcome!

 

[halcyon]

. If this is where it is expecting the excitation from then we may have found the problem. Agreement or other views are very welcome!

The warning light provides initial excitation via terminal L, terminal R is a duplicate feed for excitation. Both are provided from a common point at the key switch, and both feed the rotor at fields diodes output. The 50 Ohm resistor limits current through terminal R to approximatley that through the bulb.

Does the warning light come on ?

Check for voltage at terminals L and R.

Brian

 

[pampas]

check to determine that with the ignition swiched on that you have 12 volts present at the battery + terminal (On the alternator), if not, fit a small diode between a positive supply, the diode fitted so that it blocks any feed back to the permanent supply.

 

[Croxford]

The warning light provides initial excitation via terminal L, terminal R is a duplicate feed for excitation. Both are provided from a common point at the key switch, and both feed the rotor at fields diodes output. The 50 Ohm resistor limits current through terminal R to approximatley that through the bulb.

Does the warning light come on ?

Check for voltage at terminals L and R.

Brian

The warning light does not come on when the positive cable from the alternator is connected through the diode. It does come on however when the positive cable from the alternator is connected to a battery bank. That suggests to me that it is not getting excited in the diode configuration.

The plot thickens as I have now noticed that terminals L and R have been split into two cables of each. One off of each goes to the panel and the other two go to the Sterling regulator which I was trying not to use (this was not my doing but the work of the previous owner!). Some of the wires from the Sterling regulator are not connected so this may be the problem. Advice stiill very welcome!

 

[pvb]

The plot thickens as I have now noticed that terminals L and R have been split into two cables of each. One off of each goes to the panel and the other two go to the Sterling regulator which I was trying not to use (this was not my doing but the work of the previous owner!). Some of the wires from the Sterling regulator are not connected so this may be the problem. Advice stiill very welcome!

Why not just restore the cabling to factory default? Then it should work. If a previous owner has messed about with it, you could spend for ever trying to sort it!

 

[VicS]

I agree wire it up according to the wiring diagram in the workshop manual

which you will find at http://www.motoren.ath.cx/menus/yanmar.php

Get it all working properly.

Then refit the Stirling following the instructions for that.
On the website if its a current type but otherwise you'll have to get them from Sterling if you dont have them.

Make sure it still all works

Finally fit your diode splitter. Make sure that is just in the alternator output that you are not trying to feed the L&R terminals backwards through it. Also make sure any battery sensing is from one of the batteries.


If you have an old type Stirling booster you may be better off ditching it along with the diode splitter and fitting one of the newer Alternator to Battery chargers with a dual output.

The modern AB units require no modification of the alternator. The old type I believe requires a sensing connection to be made internally.

 

[Croxford]

Thanks. If anyone knows tha factory default settings for a Yanmar alternator I would be very greatful to receive them!

 

[VicS]

Thanks. If anyone knows tha factory default settings for a Yanmar alternator I would be very greatful to receive them!

Me being thick perhaps but what you you mean by "factory default settings"

 

[Croxford]

I agree wire it up according to the wiring diagram in the workshop manual

which you will find at http://www.motoren.ath.cx/menus/yanmar.php

Get it all working properly.

thanks, my previous post was before your reply.

 

[halcyon]

The warning light does not come on when the positive cable from the alternator is connected through the diode. It does come on however when the positive cable from the alternator is connected to a battery bank.

The positive output cable has nothing to do with the warning light or alternator excitation.

The warning light is fed from the key switch, and earthed via the rotor and regulator.

Check the voltage feed to L and R terminals from key switch.

Brian