MF-135 alternator

[flusher]

My newly-acquired 1966 MF-135 was retrofitted with an alternator years ago. It's a Delco-Remy 12-B single wire unit. There's no external voltage regulator.

Anyone familiar with this particular alternator? Is it related to the very common Delco 12SI?
Output amps?

There's a -60-0-60 amp ammeter on the dash, so I guess it puts out less than 60 amps.

Can't tell if the battery is getting charged. Will be diving into the wiring next week to find the problem. I'm probably going to rewire the tractor and use a 12SI three-wire alternator.

 

[HomeBrew2]

... Can't tell if the battery is getting charged. ...

Are you getting ~14.7 volts at the battery when it's running at speed? If so it should be working ok.

 

[Soundguy]

This may seem like a stupid question.. uh.. but .. what does your ammeter say? Charge or discharge?


Soundguy

 

[flusher]

This may seem like a stupid question.. uh.. but .. what does your ammeter say? Charge or discharge?


Soundguy

It's discharging after the engine kicks over. I run the rpm up to about 1800 to get the alternator to start charging. The ammeter needle jumps to about 0 then falls back to discharge (- amps).

Possible faulty ammeter. Possible bad alternator. Possible connection problem in the wiring.

 

[flusher]

Are you getting ~14.7 volts at the battery when it's running at speed? If so it should be working ok.

Thanks for the input. I'll check this tomorrow.

My aim in this posting is to find out if anyone has the specs on the Delco 12-B alternator. I haven't been able to find anything by googling.

 

[Birdhunter1]

That ammeter is designed to measure the amperage output of a generator, to get a gauge to properly work with that alternator get a voltage regulator.
Like everyone has said make sure to see if your alternator is putting out 13.5-14.? volts and you'll be fine.

 

[flusher]

That ammeter is designed to measure the amperage output of a generator, to get a gauge to properly work with that alternator get a voltage regulator.
Like everyone has said make sure to see if your alternator is putting out 13.5-14.? volts and you'll be fine.

Just measured the alternator output voltage at a little over 14V, so the alternator is OK.

Why a voltage regulator? The VR on my rig is built into the alternator.
Do you mean voltmeter?

 

[Birdhunter1]

Yeah that's what I meant to say, a volt meter not a regulator.
I have a 135 with the same 1-wire set up but I've yet to change the ammeter out and put a volt meter in.
I figure I'll know it bit the dust when the lights start dimming and it won't start next time i go to use it.

 

[Farmwithjunk]

My newly-acquired 1966 MF-135 was retrofitted with an alternator years ago. It's a Delco-Remy 12-B single wire unit. There's no external voltage regulator.

Anyone familiar with this particular alternator? Is it related to the very common Delco 12SI?
Output amps?

There's a -60-0-60 amp ammeter on the dash, so I guess it puts out less than 60 amps.

Can't tell if the battery is getting charged. Will be diving into the wiring next week to find the problem. I'm probably going to rewire the tractor and use a 12SI three-wire alternator.

Massey Ferguson installed ammeters along with alternators as O.E.M. installations. You don't have to have a voltmeter. If the ammeter is working, it will tell you "charge or no charge". With most folks though, a volt meter would be the preferred choice.

Check voltage at battery whith engine shut off. Check again with engine RUNNING. Any difference? (Also, how "good" is the battery?) Some single-wire alternators have lower voltage "cut-in" than others. Also, some regs are set to lower charging voltage. It's not entirely out of the realm of possibility that it's working "correctly", and yet you have no more than 12.7 volts at the battery. Check voltage at "batt" terminal of alternator (while running) (terminal to ground) Check same place with engine shut off. Any difference there? Does output (at "batt" terminal of alt.) increase with engine RPM's? If so, to what level?

Helps to know what you're working with. (specs on current regulator)

I've just finished wiring a friends 135 (after a "wiring mishap"), and completely re-newing the charging system on my 150. I did both as wired originally. (External regulator/3-wire alternator/ammeter), and recently wired/installed a 1-wire alternator on another tractor. Piece of cake.... But along the way, I came to the realization that many old tractors have, over time, fallen victim to being wired in some rather unorthodox methods. Best to start from scratch, assuming nothing is correct. Don't even take for granted all the current wiring is good. Check each and every wire with an Ohm meter (or replace them). I spent months chasing gremlins because of one wire that would make intermittant connection. (stranded copper, wire broken with-in insulation. worked when tested. Didn't work when tucked back under dash panel. (field voltage from reg to alt.)

 

[Soundguy]

That ammeter is designed to measure the amperage output of a generator, to get a gauge to properly work with that alternator get a voltage regulator.
Like everyone has said make sure to see if your alternator is putting out 13.5-14.? volts and you'll be fine.

That's plain bunk... DC current is DC current... doesn't matter to the gauge whether it comes from a battery, an alternator, a generator, or a battery charger.... electrons are electrons....

Biggest difference in the output of an alternator and a dc genset is that most modern alts kick out 37+amps.. and most dc gens kick out 25 or < amps.

An ammeter is a 0 center gauge.. it is used to measure net charge to the battery.. NOT the amperage out of the generator or alternator.

When the electrical system is in a state of discharge, the needle deflects to the negative side of the gauge.. denoting reverse current flow in that wire.. which means the storage battery is providing current to run the electrical load due to a load situation that exceeds the charging systems capability.. or in the case of a non functional chargeing system. A net charge shows up as a positive needle deflection denoting current moving toward the battery, thus charging it.

An Amperage gauge is generall a gauge reading from 0 to? ( 30 or 60 ).. and that is generally used to show total amperage output of a generator or alternator. While both an ammeter and an amperage gauge measure current flow.. thier use is dictated by application.. an ammeter can be use din place of an amperage gauge providing there is sufficient gauge range as to make it usefull.. however am amperage gauge is not a suitable replacement for an ammeter as it cannot show a negative deflection.

A voltmeter can be usefull in conjunction with an ammeter.. but if I could only choose 1.. i'd take the ammeter... tellms me about the state of the battery by looking at the charge rate... a voltmeter can't tell you that as easilly.

My advice to the poster with the odd gauge reading is to check wireing and then replace the ammeter.. they cost about 9$ for a cheapy sunpro. Then.. look for a positive needle deflection on the gauge, and if needed.. the charge voltage on the battery with your vom, or auxilary voltmeter gauge.. etc..


Soundguy

 

[Farmwithjunk]

That's plain bunk... DC current is DC current... doesn't matter to the gauge whether it comes from a battery, an alternator, a generator, or a battery charger.... electrons are electrons....

Biggest difference in the output of an alternator and a dc genset is that most modern alts kick out 37+amps.. and most dc gens kick out 25 or < amps.

An ammeter is a 0 center gauge.. it is used to measure net charge to the battery.. NOT the amperage out of the generator or alternator.

When the electrical system is in a state of discharge, the needle deflects to the negative side of the gauge.. denoting reverse current flow in that wire.. which means the storage battery is providing current to run the electrical load due to a load situation that exceeds the charging systems capability.. or in the case of a non functional chargeing system. A net charge shows up as a positive needle deflection denoting current moving toward the battery, thus charging it.

An Amperage gauge is generall a gauge reading from 0 to? ( 30 or 60 ).. and that is generally used to show total amperage output of a generator or alternator. While both an ammeter and an amperage gauge measure current flow.. thier use is dictated by application.. an ammeter can be use din place of an amperage gauge providing there is sufficient gauge range as to make it usefull.. however am amperage gauge is not a suitable replacement for an ammeter as it cannot show a negative deflection.

A voltmeter can be usefull in conjunction with an ammeter.. but if I could only choose 1.. i'd take the ammeter... tellms me about the state of the battery by looking at the charge rate... a voltmeter can't tell you that as easilly.

My advice to the poster with the odd gauge reading is to check wireing and then replace the ammeter.. they cost about 9$ for a cheapy sunpro. Then.. look for a positive needle deflection on the gauge, and if needed.. the charge voltage on the battery with your vom, or auxilary voltmeter gauge.. etc..


Soundguy

Why is it everyone seems to want a voltmeter? I mentioned in an earlier post that it was the "prefered gauge with most folks". The counter guy at my friendly neighborhood NAPA store was utterly dismayed when I ordered an new ammeter.(Top of the line AutoMeter gauge was only $21) He wanted to know why I wasn't replacing it with a voltmeter "like everyone else does". I can't see why an ammeter is looked down upon by so many. It tells you "CHARGE, NO CHARGE, or DISCHARGE" with one quick look. Almost as simple as an idiot light, but far more informative. From all I can understand, ammeters are all an electrical expert would need in most cases, and all a complete novice would need in most cases.

 

[Soundguy]

Why is it everyone seems to want a voltmeter? I .

I agree...I'm not sure either. I think it is for people that don't know anything about electronics.. I.e. an 'idiot gauge'. The average person (mostly) knows their car/truck/tractor has a 12v battery.. and as long as they see the needle at 12v or above.. they think they are safe.

But they can be wrong. I've seen PLENTY of batteries with 1-2 dieing cells. With the alternator going, the system voltage stayed at charge voltage.. 14.x .. etc.. though the alternator was pumping out extra amps to keep it that way.. as soon as the vehicle turned off.. the bat's would drop to 8v.. and be flat overnight. An ammeter would have told them what was going on... like.. "hey you" your charging at 20A.. even though you have been running for 5 hours... CHECK OUT WHY...

That's why i prefer an ammeter... charge current will tell you lots of things about your battery.. ( as you point out as well ).

Soundguy

 

[jimmysisson]

I second the motion to check all the wiring as if it were suspect. My 135 had a similar intermittent open wire to the alternator - it would charge if you jiggled the wire just so - bad connection to a wireless terminal someone put on. Start from scratch with a wiring diagram. 1974 135 with oe alternator and ammeter - worked fine.
Jim

 

[Farmwithjunk]

I second the motion to check all the wiring as if it were suspect. My 135 had a similar intermittent open wire to the alternator - it would charge if you jiggled the wire just so - bad connection to a wireless terminal someone put on. Start from scratch with a wiring diagram. 1974 135 with oe alternator and ammeter - worked fine.
Jim

One wire..... a 14 ga. wire from the field lug on the regulator to the field terminal on the alternator..... Liked to drove me stark raving mad.

I would take the side panel off, exposing the regulator and wiring, pull the cluster of wires down where I could check everything, and all was well. Shove it back in place to install the cover, and I'd loose field voltage to alternator. No charge. Wire ohmed out when tested. I THOUGHT there was a problem with the regulatorS I was getting. Went through 3 of them. Fortunately, I have a friend in the auto electric business who would let me return the regs for another. I FINALLY gave up and started replacing wires. I replaced the green wire and everything started working. AMEN! When I found the broken stranded copper wire, it seems so simple, yet it never really made itself obvious.

36 year old wire that's spent its life in a harsh environment, surrounded by heat, diesel fuel, dirt, dust, vibration, cow manure, and a half#$$ mechanic doesn't stand a chance. When in doubt, replace.