Alternator not charging with a Next step 12P reg.

[KASHMIR]

I have a second alternator with a 15 year old next step reg. I have had the alternator checked and the man says its fine, I have triple checked the wiring and found no issues, I have done the Next step diag list and found nothing abnormal. The green LED looks like its flashing 3/1 which is "lock", whatever that is. The only thing I find which is unusual or suspicious, is the field wire has battery volts when running the engine and 5 volts when I unplug it from the alternator.

I am a bit of a whits end with it.

Any help appreciated (of course)

[smac999]

If the field wire has battery voltage but the alt is not working then its the alternator.

Disconnect the field from alt. and jumper 12v direct from battery to field post on alt (with a 10a fuse). it will ether work or not. If not alt is bad. If it works reg is bad. Do not leave wire hooked up for long.

Is this an existing setup or a new one? Ie you sure it's an externally regulated Alt?

I don't know about the 5v. 5v or les is normal field voltage with full batteries. But I don't know shy it would change when unplugged as battery state would be same

That is what regulator does. Adjusts field voltage from 0-12v to adjust amount of charge.

[Cheechako]

I had a couple Next Steps and they were great. unfortunately I cant remember the details about adjustments on them. Can you call Ample Power ?(they are some other name now...) 5Volts doesn't sound right. The above advice is good though.. just connect 12V to the field and the alt should be putting out gangbusters.... you'll hear the engine slow down when you connect it...

[KASHMIR]

Originally Posted by smac999

If the field wire has battery voltage but the alt is not working then its the alternator.

Disconnect the field from alt. and jumper 12v direct from battery to field post on alt (with a 10a fuse). it will ether work or not. If not alt is bad. If it works reg is bad. Do not leave wire hooked up for long.

Is this an existing setup or a new one? Ie you sure it's an externally regulated Alt?

I don't know about the 5v. 5v or les is normal field voltage with full batteries. But I don't know shy it would change when unplugged as battery state would be same

That is what regulator does. Adjusts field voltage from 0-12v to adjust amount of charge.

It's a re-built old setup, I had the alternator re-built and its never really worked properly since.
I have done the battery direct to field thing and it was drawing about 4 amps into the alt but no supply to battery so I guess the alt is dead. I think I will just buy a basic internally regulated unit and forget the next step.

[Cheechako]

Not sure why you want to abandon the Next Step if your alt is bad. They are a great regulator and get you more amps out of your alternator. If you are a single belt drive just get a small frame 75 amp or 100 amp max alternator. Older Balmars, or ample power ones aren't very expensive if you can find one used.
later.. ahh.. I see you are in Oz... maybe harder to come by old Balmar etc alternators over there.
Something like this might work... apparently the v belt pulley can be added.... http://www.ebay.com/itm/Balmer-Alter...9d9535&vxp=mtr

[KASHMIR]

I decided to give the alternator another go and took it to a different auto elec. The diodes were blown to bits and the bearings were stuffed! So much for the earlier re-build. Perhaps it was a Dulux re-build.
So I re-fitted the alternator and it charges at 80 amps, the auto elec told me that it would overheat and blow up again if pushed too hard. Bear in mind this alternator was sold to the PO as a 120amp high power unit, I have been told now that it is likely to push only 40-50amps without blowing up again. So I will try and drop the next step output down to that level. I will also put a little temperature indicator on the body of the alternator.

[Neptune's Gear]

Peter, if it is not a hot rated alt, then it will die again if pushed. That is what your 2nd repair guy is getting at, IMO.
The Next Step regs do push the alternator when the bats are down a bit. If the bats are never down much, what you have will work, possibly for quite some time.

The fault is neither with the reg, which is working fine, nor the alt, which is (now) also fine, but the fact that they are a mismatched pair. The reg is good for a boat, but the alternator is less than ideal for the task it has been given (charging a house bank, right?) in your boat. If you replace it, get a good hot rated alt, and you will have years of trouble free charging.

[smac999]

Can you drop the next steps down? The balmars do it with the belt settings.

[KASHMIR]

Yes, they have a couple of trimpots used to reduce load on small engines.