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