High output alternator

woodster · Dec 14, 2014

PeterBreit said:
I have a 2000 Beneteau 461 with a 50A alternator.
Since the tachometer stopped working I had a reason to get a new alternator.

I replaced it with an API 120A internal regulated alternator from Go2 Marine.

It fits perfect but will not charge ?!
There are no markings on the back side like + or - Bat. There is also a fairly long bolt which has painted blue head. What is it for ? Does this has to be removed before installing.
Also the tachometer is not working, just comes on occasionally.

The picture shows the blue bolt at the 3:00 position

Peter Breit
"BELVEDERE"

BreitP@Outlook.com

you may have to ground it to the engine ground in order for it to work look for an "E" terminal on it and run a ground wire from there to the engine ground and use heavy gauge wire when you do ...you can use a temp jumper to test this theory out and then proceed to final grounding if you find that is the case

centerline · Dec 14, 2014

PeterBreit said:
Because the original alternator did not have a separate ground wire I didn't think of that.
Maybe that what this Blue bolt is for, would make sense.
Thank you very much..
Peter

absolutely... the blue bolt at the 3oclock position is a ground bolt only.... it can be removed and there is only a threaded hole left in the housing... BUT, it should ground thru the foot mounting of the unit just as well if the block is grounded. but you may want to take a 10ga ground wire directly to the battery (or to the starter ground) from the blue bolt... but it really shouldnt make any difference if the engine block is grounded properly...

centerline · Dec 14, 2014

check the wiring for a short or poor connection.... use a continuity tester or multimeter set to ohms and it will be easy..... 1 will be maximum resistance, or open circuit, and 000 will be no resistance, or closed circuit, which is what you want in the wire from one end to the other..
sometimes you may get a 006, 013 or some other random number with the 0 in the front of it... this designates resistance in the wire and usually means there is a poor connection somewhere between test lead1 and test lead2.....

centerline · Dec 14, 2014

one other thing I have found on conversion units is, sometimes the plug where the black and red wire is, can have the connections backwards... what this can sometimes cause is a failure to excite the alternator... or for the battery to discharge itself backwards thru the alternator when the system is not running.
its hard to imagine that your other alternator failed, then the new one is faulty also, but possible... I would look closely at the wiring

you should be able to pull up a wire diagram online that shows what all the wires do and where they go....these internally regulated alternators have a simple wiring schematic.
and there may be a fuse blown near the keyswitch that is not letting the alternator excite properly..

where the tach wire is connected to the alt, it is an AC tap that should generate about 7vAC to drive the tach, when the alternator is turning. it is a pulsed voltage but its too fast to see the pulsing on your meter.

Stu Jackson · Dec 14, 2014

You should also consider doing a Google search for "12V alternator handbook." It's a PDF of a very good writeup of how alternators work.

Many OEM alternators were case grounded, using the mounting hardware for the ground. Newer high output alternators may be case grounded too, but all can use a separate ground wire from the case to the engine ground.

Ron20324 · Dec 14, 2014

Blue... I would have guessed a temperature sensor.

Hey, Peter, we missed you at the SOS party last night and today's brunch. I guess you're on the water somehwere warmer? A Beneteau club boat won the POL best in show.

ALNims · Dec 14, 2014

PeterBreit said:
I have a 2000 Beneteau 461 with a 50A alternator.
Since the tachometer stopped working I had a reason to get a new alternator.

I replaced it with an API 120A internal regulated alternator from Go2 Marine.

It fits perfect but will not charge ?!
There are no markings on the back side like + or - Bat. There is also a fairly long bolt which has painted blue head. What is it for ? Does this has to be removed before installing.
Also the tachometer is not working, just comes on occasionally.

The picture shows the blue bolt at the 3:00 position

Peter Breit
"BELVEDERE"

BreitP@Outlook.com

Peter,
Your best bet is to contact the engine manufacturer and find out the recommended alternators for your yacht. The engine manufacturer should also be able to give you the correct hook up for the alternator.
Andrew

Bill Roosa · Dec 14, 2014

Does it need an external regulator perhaps? Stock alternators usually don't have external regulators and well most high output expect to have one. The only reason I ask is you did not know about the ground wire and are not asking about any other wires (the first thing most ask....). with out a regulator the alternator will act like you are describing.

ALNims · Dec 14, 2014

PeterBreit said:
Well, I connected a 10g ground wire. The alternator shows no output at idle speed, actually the red "Charge" light on the engine panel in the cockpit is on. It gets dimmer when I increase the RPM and there is about 16-20A output. Whish is about the same as the battery charge puts out in the second stage. Battery voltage is about 12.5V on my house bank 3 4D AGM batteries.
But the Tachometer is still not working. The leads on the alternator are all tight. I am not sure where the problem is...?

I was checking the website for your alternator. I noticed that they had a part number with a "T" that specifically calls for a tachometer. Did you order that option. I also looked at your engine manual. Are you sure that you have an alternator compatible with your system?

seadaddler · Dec 15, 2014

Plug

I just changed my alternator and just to be sure took it to
alternator rebuild and asked and he said some times the
plug in 2 wires could be back wards.
My new alternator is working fine so far and I did have a problem
with my tach also and tried everything under the sun even purchased
a new tach VDO from internet and still was crazy tach,so far with
new alternator it seems to work but still early to know for sure
and need to go motoring for longer time to see if tach is working better.
Nick

slaume · Dec 15, 2014

I don't think the engine cares which alt it is spinning as long as the belt and brackets match up. The entire charging system definitely cares how it is wired.

The fact that the original post was asking what the ground bolt is for seems a bit disturbing. If the alt was not wired properly and then run, it could have fried the diode in the alt. Inadequate wire and or fuse sizing could be a fire hazard.

The charging circuit handles a good bit of current and should be taken seriously. When I changed my charging system to a larger alt with an external regulator and echo charger for the start battery, I had a very detailed schematic with recommended wire and fuse sizes for the system. I dealt with Jack Rabbit Marine at the time and they were very helpful. They supplied a couple of different ways to wire the system. There are also some great books on marine electrical systems that will include wiring an alt.

I keep Don Casey's book on the boat along with a multi meter and a bunch of spare wire and crimp fittings.

Get a hold of some wiring diagrams for the alt and make sure it is hooked up properly, before you start the engine, Steve.

slaume · Dec 15, 2014

seadaddler said:
I just changed my alternator and just to be sure took it to
alternator rebuild and asked and he said some times the
plug in 2 wires could be back wards.
My new alternator is working fine so far and I did have a problem
with my tach also and tried everything under the sun even purchased
a new tach VDO from internet and still was crazy tach,so far with
new alternator it seems to work but still early to know for sure
and need to go motoring for longer time to see if tach is working better.
Nick

If you change your alt or tach, you need to make sure the tach is calibrated to match the alt. There is a tiny little ajustment screw on the back of the tach that can be changed to match the two together. If it is set wrong the tach will read incorrectly, Steve.

kgodfrey · Dec 15, 2014

Peter,

Your new alternator is a cloned Delco 10SI. It was originally designed to be a 63A alternator. It was replaced by the 12SI which with improved cooling could go up as high as 94A. Also looks like a Yanmar installation but I could be wrong. If it's a Yanmar installation that means you have a single 1/2" v-belt which limits power drive to the alternator at max 100A. So don't expect a long life from that puppy especially since you mentioned that your house bank is 3-4D AGM's.

Here's the wiring details for that alternator. You have the Bat wire correct but it's too small awg for what you are asking the alt to do. Should be at least 2awg if the run is short. The 10SI is case grounded, to confirm check the continuity from the case to your battery neg terminal. TBut it looks like you have an existing case ground wire...the silver painted one. The problem might be having the two wires crossed in the 12:00 plug. Both function to operate the idiot light.

If it a Yanmar and I think it is, the alternator has no function in the Tach. the tach is driven off an engine sensor.

Good luck!

kgodfrey · Dec 15, 2014

PeterBreit said:
The Positive red one is in the 10:00 position. Next to it 11:00 position is the tachometer pick-up lead (not a ground wire). I grounded the alternator from the bolt seen at 3:00 with a 10g wire to the engine ground connection. I talked to API customer service. I was told the existing red positive lead should be heavy enough. It looks like a 10gauge.
The original Hitachi 50A alternator was working fine except the tachometer stopped showing. I assumed the pick-up in the alternator went defective. and since I wanted to upgrade to a high output alternator anyway I switch to the API 120A. But I expected the tachometer to work. Maybe it is a short in the wire running from the alternator to the tach in the cockpit. Tough to check for continuity...
Thanks for your help

Peter,

Do you have a Yanmar engine? If so, the tach does NOT get it's signal from the alternator. There is a sensor on the flywheel housing that picks up the speed of the ring gear teeth passing beneath it and converts that to a pulse which is sent to the tach.

The painted grey wire you believe to be a tach/stator lead is in fact your ground wire. Look at it's gauge, it's the same as the red Bat wire. If the folks at API told you that the terminal that your grey wire is connected to is the stator/tach take off then I think your problem is solved as far a the alternator is concerned. Disconnect the painted grey wire from it's current terminal and reconnect it to the blue bolt which is your ground.

I've rebuilt and rewired a few Hitachi alternators and on a Yanmar there are only four wires on the rear. The big red one which is Bat, the big black one which is ground, the L terminal which feeds the idiot light and the R terminal which is the parallel resistor circuit in the idiot light sequence. Both the L and R terminal are fed juice through your ignition switch.

I hope this helps, maybe MS can add his perspective as well.

kgodfrey · Dec 15, 2014

the L and R terminals are in the 12:00 plug. They function to excite the alternator before it's rotating and later to work the idiot light circuit.

As to the tach's problem it's either the flywheel housing sensor, tach or wiring in between that causing that problem. Swapping out the alternator was a not the answer I'm afraid.

The sensor has two wires, orange and blue/red. It gets it's power from the tach itself. Those power wires at the tach are red/black and black. I'd check for power at the tach first with the key "on". You need a special tester to test the sending unit, it called a synchroscope. So you would need to have an Yanmar engineer check that for you.

High output alternator

.

Attachments

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.