India Alternator Trouble Shooting

[Horsepoor]

I have a Metro 6/1 that came with an India alternator installed. It functioned for awhile but I just noticed it is no longer charging the battery. My problem is I dont know anything about these units, I like the small size, limited output (I.e. Less than 30 amp) which is just perfect for driving the 12 volt - 17 amp rated cooling fan and my emergency over temperture shutdown system. I figured someone on the forum must be familar with common problems which will save me a lot of aggravation and time.

In the attached photo, there are two spade contacts. I measured an AC voltage of 26 volts indicting the diode bridge in not rectifying AC to DC. I am considering taking the Alt apart to see what is inside or I could just hook up one of my large 50 A bridge rectifyers and perhaps call it a day. Oh, I wonder of the voltage regulator in the original configuration before failure was on the AC circuit or after the rectifier on the DC. Any input that will save me time would be appreicated.

[mobile_bob]

while the engine is running at speed, take an end wrench and touch it to the end of the alternator shaft where it comes out of the pulley
see if there is a strong magnetic attraction, or at least moreso than when the engine is shutdown.

the two spade terminals having 26 volts on it makes me think you have a 24 volt alternator?

those two spades generally go to the brushes and not the stator in my experience,

is there an external regulator mounted somewhere?

bob g

[Thob]

First of all, disclaimer: I'm not familiar with the alternator you have.  But ---

Most alternators use the voltage regulator to drive DC, from the battery at first, to power the field (rotor).  Many of them get the initial power thru the idiot light, so they don't draw power when the key is off.  Some won't work if the idiot light burns out.  Some can get going if enough residual magnetism remains, even if the battery is dead.  Once it starts producing power, it has plenty of DC to power the field (it gets the power for the field AFTER the rectifier).

Most alternator armatures are setup for three phase; they use 6 diodes for a full wave rectifier.  The ones I've seen are typically pressed into the aluminum case at the rear of the alternator.  It sounds like yours are bad, they can be checked with an ohmmeter but you need to open up the alternator and disconnect wires to check them.  I'm guessing that with open diodes, the regulator is pushing all it can thru the field, and hence the 26 volts you see.

Standard bridge rectifiers usually only contain 4 diodes for rectifying single phase; it should be possible to use 2 standard bridge rectifiers (actually, 1 1/2) by opening up the alternator, getting access to the wires, and mounting the standard bridge rectifiers on a heat sink outside the unit.  It's a kludge compared to getting the "proper" parts, but should work.

Whatever you do with it, be careful that it doesn't overcharge your batteries or burn itself up - watch it closely after you put things together and start it back up.

[TimSR2]

Best option is probably to toss it and convert to a Delco 10SI.

[Horsepoor]

I've had time to think, read the replies, and research. Looks like the India alternator is clone of something. I am sure it is a 12 Volt unit with about 30 amp capacity. There is no brand label but I'll bet it is a copy of a reliable and proven product that is cheap to manufacture. After research, I now know what a 3 wire Alt is and this looks like a 3 wire setup with only two wires. So my Satuday project is to ensure a proper 3 wire setup with #1 wire going to the battery, #2 wire sensing voltage (sometimes used to excite the Alt), and #3 wire to idiot light. When I am certain I have it wired properly (no paperwork on the mystery Alt) I'll see if it works. If not I intend to do the following:

Check the magnitic field with an end wrench as suggested. If functional I intend to move on and place a small load on this 26 volt AC source to see if the power falls away to nothing. If it hold close to 26 VAC then I am going to take it apart, and test the diodes.

If I run into any aggravation, or it takes more 20 minutes to accomplish the above, I am going out and buy a three wire Delco 10 SI. Having read a lot over the last couple of days, I am convinced this will be a good $75 investment. Easy to trouble shoot, buy parts, etc. I would like to get the 37 amp model instead of the more common 63+ amp model(s), but I'll find out when and if I have to cross that bridge. Thank you for your input, the posts were helpful. 

[Lloyd]

Horesepoor,

Take a look hear..
and here
think you have a  nippo/denso...I'll just bet when you get it open..this link will make senses of the story.

I see from the pic you posted that you have a 2 wire plug, with a 3rd lug for bat.

It might be a Lucas..which ND knocked off. Or it's a Lucas/India knock off.

Let us know.

Lloyd

[Horsepoor]

Excellent information. Added the missing third wire which excited the alternator, makes 14.92 volts DC, puts out 20+ amp changing a run down battery - EVERYTHING ON THE CHARGING SYSTEM WORKING PROPERLY. Attached is a quick reference photograph, reflecting with the jump wire lifed slightly about the proper terminals. Photo is  little blurred but engine is running when I took the photo. Thank you.

[Lloyd]

Horesepoor,

Make sure you run both the lamp and excite through a switch/ other wise it's likely to flatten your battery when the motor is not running.

Lloyd

[Horsepoor]

Makes sense, thank you.