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4023 only producing half the amps - does it need rebuilding?

PostPosted: Sat Oct 27, 2012 7:21 pm
by Alex N
I have an Ample 4023-S coupled with a NEXT Step Regulator.
System was professionally installed by Power Wave in Vancouver and has been very good. We cruised across the Pacific and are now located in Malaysia.

There have been two occasions where I have had to rebuild the alternator and I believe I must do it again.

The Alternator was installed at around 750 hours on the Engine. At 1250 hours I had to replace diodes and heat sink as the alternator was no longer producing full amps. This was back in 2001 and I admit that its a bit foggy now but I recall I had some problems doing this myself and may not have done it altogether correctly. However the alternator worked fine. At 1800 hours the alternator stopped working and was rebuilt by a firm in Fiji. They replaced diodes and I believe replaced the windings on the rotor. It worked fine since then and now we are at 3650 hours and the following is what is happening.

Situation Now.
The alternator is no longer outputting the max amps. Usually when cold and batteries discharged, the alternator will be outputting about 80 or 90 amps. This would slowly reduce as the voltage increase as controlled by the regulator. I've never seen the rated 124 amps which I guess is due to the size of the alternator pulley vs. engine RPM and pulley size on engine.

A couple of days ago, this stopped happening. The max output I see is 40 to 50 amps. I changed and tightened the belt and checked all connections and found them to be tight. There are no error lights on the NEXT Regulator. The performance I am seeing is similar to when I had to rebuild the alternator last time

Yesterday we motored for approx 7 hours and the output amps started at about 50 with the voltage at 13.05. Towards the end of the day the amperage was around 30 and the voltage had raised to 13.8 or 13.9. Finally, the next shut off the charging and the amps reduced to a nominal 5 or 6 and the voltage at 13.2. So it appears the the next charged the batteries with what was available.


My questions:

1. Would you suspect the alternator needs to be rebuilt?
2. I am considering purchasing a new alternator from you because the current one has been well used and would consider rebuilding it and keeping it as a spare.

Of course getting things here to Malaysia is costly and time consuming and I don't want to get a new alternator unless it is prudent to do so.

Thanks,

Alex

Re: 4023 only producing half the amps - does it need rebuilding?

PostPosted: Sat Oct 27, 2012 11:58 pm
by Coulomb
There's an output versus RPM table for the alternator here: http://www.amplepower.com/products/alternators/index.html

Output should be close to this table, assuming that the battery voltage has not reached the absorption setpoint. There are three phases, so failures are likely to be in 1/3 increments.

Generally it is the bearings that fail, not the diodes, but if some of the diodes fail, then output can be reduced. Failure of the diodes is related to excess heat. Belt slip can cause that, or lack of cool air at the alternator.

Spares are alway good, especially spares to keep the electrical system alive.