Charging problem

[bruce1966us]

I know I am shooting myself in the foot from the Yanmar parts outlook but the Kohler regulator is $36 retail. I forgot to get the part # from the shop but will get it ASAP.

Thanks,
Bruce
parts@yanmartractors.com

 

[Keoke]

Voltage regulators sense system voltage at battery and then tell the alternator what the charge rate ought to be. Voltage at battery is proportional to electrical load and battery state of charge. When load is high (voltage low) alt is told by VR to charge high and when load is low and battery is up (voltage high) alt is told to charge low. Keep in mind we are talking about battery voltage here and not alt voltage. Every voltage regulator has a SENSOR tap or wire that is tied to the bat B+, the closer to the bat post itself the better. This input is how the VR knows what the bat voltage is.
Once the VR gets this info it then modulates the alt output by varying the field current in the alt. Hi fld current gives a high alt charge rate. Mechanical (adjustable) VR's will use a vibrating relay coil to vary field strength and solid state units use Zenner diodes to cycle a switching transistor that turns the field current on and off at a rapid rate. The rate of ON time compared to off time is proportional to system voltage.
Low voltage gives more ON time and high voltage more OFF time.
The above is the same for all voltage regulators, so getting something other then the OEM unit to work on your tractor is not hard to do.
They are two types of field circuits, the "A" type and the "B" type. In the "A" type the field coil is fed B+ from the bat and the VR modulates the gnd side to vary the field strength. Most, but not all, solid state units are A's.
In the "B" type the coil is grounded at one end and the VR modulates the B+ into the input end.
You need to know which type you have (A or B) before you can shop for an other then OEM replacement.
The cheapest and most simple (two wires) "B" type VR would be from a Chy corp vehicle about 1965 to 1980 this is a mechanical unit. The later Chy corp vehicles used a "A" type solid state unit, also two wire.
Hopes this helps.
If you can send a wiring print of your system it would help.

cheers,

 

[gbirky]

Keoke,

I appreciate all the information, but I still don't think you are getting the picture. This is a PERMANENT MAGNET alternator. There is no field, or field current to vary. I have already attached a scan of the diagram for this charging system. I'll attach it again here.

My question is a simple one. Will the system charge properly if the VR is just a relay which closes to ground the AC from the alternator when the battery voltage goes above say 14 Volts. If so, where can I obtain such a regulator/relay.

Greg

Greg

 

[Keoke]

Your post of 4/25/02 said that both your alternator and DIODE BRIDGE are working fine. I assumed that the diode bridge that you are talking about is in the alt. If this is the case then you have DC not AC coming out of the alt.
You cannot do anything with the AC coming out of the alt until you change it to DC. Look at my post on using the diode bridge from a Delco 10si alternator to do this job.
You cannot run the AC to ground since 1/2 of the sine wave would be a dead short (pos to neg).
All you need to do on your unit is convert the AC output to DC with the diode bridge. No cut out or relay is required since the diode bridge between alt and bat would be in reverse bias and no current can flow from bat to alt with engine off.

cheers,

 

[gbirky]

Keoke,

Did you take a look at the diagram I attached to the last post? (I attached it here again). The diode bridge is on the back of the alternator and is working, but the regulator is not. There are two wires from the alternator - one goes to the VR and this is AC, unrectified. The other wire from the alternator goes to +B, and this is rectified. The VR has 3 wires. One goes to the alternator AC as I said above. The other two wires from the VR go to +B and ground.

If the VR senses +B voltage, and closes a relay to ground the alternator AC, I think this would cause the system to stop charging. The rectified output of alternator no longer produces voltage. All I'm trying to do is figure out what exactly the VR does in this setup. It doesn't rectify, because the diode bridge on the alternator does that. It cannot regulate charging by varying field current because the alternator field is from the permanent magnets in the alternator. How does this setup vary charging. Does it just turn charging off by grounding the alternator AC when +B voltage is high enough? That is all I want to know.

Greg

 

[bruce1966us]

Here is the Kohler part# 41-403-05 This is a B+ type regulator rated for 15 amps.

Bruce

 

[Keoke]

Greg, I know you got 30 AC at point Y at alternator. You should also get 14/15 volts DC at alt point R which is the DC output of unit. If you don't get 14/15 volts here and have 30 volts at point Y then you have a problem with your alt diodes coverting AC to DC. Most likely open diodes.
Since your alt has a PM field, taking wires Y and R off at VR should let your alt run wild (charge max) if it is a full working unit.
Don't really understand your VR role in circuit as shown.
A maybe theory here would have the Y wire sending a signal into VR that turns on a bleeder circuit only with engine running (AC signal). Bleeder circuit would go off with engine thus taking care of a battery back feed problem when engine is off.
A voltage regulator acting as bleeder unit and dumping off excessive charging voltage to gnd at VR is not comon but has been done with low amp units. Since this is a low charge alt we are not talking of a lot or wattage (heat) here. Soundguy mentioned this type of VR in his post earlier.
Also, if you show 15V at alt R point but not at bat then with engine running try hooking a heavy jumper wire from terminal R at alt to bat B+ and then measure bat voltage again to check this out. If you have 14/15 DC at alt term R and just 12.6V at battery then my guess is an open between these two points.

cheers,

 

[Soundguy]

Not exactly. ( yes and no )

A charging system with a shunt ( like a zenir diode setup ) could be used.. but there are much better ways to do it.

I would personally rectify it through a bridge rectifier, then find a solid state regulator, ( may be hard to locate for that amperage load, but could be made with either a bank of lower power devices, or could be made with a 2n3055 transistor, in a series pass regulator circuit. )
Then filter for emi/rfi, and on to the battery. But that is just me....

Soundguy

 

[Soundguy]

This is good infor for the alternator people.. laid out nice and easilly understandable.... unfortunately this guy has a dc generator.. fixed perm./ magnets for field.

Regulating charging current is either going to be solid state and elegant.. or a variable shunt, down , dirty, and wastefull.

Soundguy

"Voltage regulators sense system voltage at battery and then tell the alternator what the charge rate ought to be. Voltage at battery is proportional to electrical load and battery state of charge. When load is high (voltage low) alt is told by VR to charge high and when load is low and battery is up (voltage high) alt is told to charge low. Keep in mind we are talking about battery voltage here and not alt voltage. Every voltage regulator has a SENSOR tap or wire that is tied to the bat B+, the closer to the bat post itself the better. This input is how the VR knows what the bat voltage is."

 

[Soundguy]

I agree.

The schematic as posted .. is missing a bit of needed circuitry. Could this have been some 'non-working wizadry from a previous owner trying to sell the tractor?
I soppose that the vr could have a large variable resistor setup dumping some of that ac to ground before conversion, and that wouls be protected by the diode bridge when the unit was off ( no reverse flow to discharge the battery )
Again.. terrible design... I would change it to solid state... but then... not my tractor... Would probably be alot easier to just buy the oem part.
I know the guy is just trying to understand the circuit as wired.. but it has defficiencies ( #1.. it doesn't charge, #2 there is some question as to wether certain parts are working, and #3, wether it is plumbed correctly. )
Anyone have a shop manual for this tractor that shows a charging schematic?

Soundguy

""Greg, I know you got 30 AC at point Y at alternator. You should also get 14/15 volts DC at alt point R which is the DC output of unit. If you don't get 14/15 volts here and have 30 volts at point Y then you have a problem with your alt diodes coverting AC to DC. Most likely open diodes.
Since your alt has a PM field, taking wires Y and R off at VR should let your alt run wild (charge max) if it is a full working unit.
Don't really understand your VR role in circuit as shown.
A maybe theory here would have the Y wire sending a signal into VR that turns on a bleeder circuit only with engine running (AC signal). Bleeder circuit would go off with engine thus taking care of a battery back feed problem when engine is off.
A voltage regulator acting as bleeder unit and dumping off excessive charging voltage to gnd at VR is not comon but has been done with low amp units. Since this is a low charge alt we are not talking of a lot or wattage (heat) here. Soundguy mentioned this type of VR in his post earlier.
Also, if you show 15V at alt R point but not at bat then with engine running try hooking a heavy jumper wire from terminal R at alt to bat B+ and then measure bat voltage again to check this out. If you have 14/15 DC at alt term R and just 12.6V at battery then my guess is an open between these two points.

e.""