Voltage Reduction

[Tapage]

Ok .. here more testing ..

Start engine and resistor get hot like hell .. I was seen 14.6 V on the alternator side of the resistor .. so I disconnect it try with the 7805 and same thing happen getting hot like hell ( can't be touched ).

I disconnect the plug from alternator and start the engine, was getting battery V ..

provide 12V briefly to the L port and it start charging 14.6 - 14.7 strong ( and you can tell the load on the engine by rpm ) connect the S ( sensing ) port to the battery so the Alternator can see how much V was putting and indeed it regulated and got back to 13.2

Since I had my battery charger previously connected I'm not sure at this point the alt was charging at all ..

if I disconnect the S port it raise back to 14.6 - 14.7 level . so that part was ok ..

If I left the S port connected to the battery, it would stay low .. I mean stay " charging " around 13.0 - 13.2 V no matter how much rpm you put on the engine ( so maybe it stop charging and was just battery V )

If I provide 5V or 12V to the L port the alt immediately start charging to 14.7 if I disconnect it ... it will stop charging.

Dunno if matter but when I touch the L port with positive V ( 5V or battery V ) I saw few sparks .. like a small short ?

 

[george_tlc]

Ok .. here more testing ..

Start engine and resistor get hot like hell .. I was seen 14.6 V on the alternator side of the resistor .. so I disconnect it try with the 7805 and same thing happen getting hot like hell ( can't be touched ).

I disconnect the plug from alternator and start the engine, was getting battery V ..

provide 12V briefly to the L port and it start charging 14.6 - 14.7 strong ( and you can tell the load on the engine by rpm ) connect the S ( sensing ) port to the battery so the Alternator can see how much V was putting and indeed it regulated and got back to 13.2

Since I had my battery charger previously connected I'm not sure at this point the alt was charging at all ..

if I disconnect the S port it raise back to 14.6 - 14.7 level . so that part was ok ..

If I left the S port connected to the battery, it would stay low .. I mean stay " charging " around 13.0 - 13.2 V no matter how much rpm you put on the engine ( so maybe it stop charging and was just battery V )

If I provide 5V or 12V to the L port the alt immediately start charging to 14.7 if I disconnect it ... it will stop charging.

Dunno if matter but when I touch the L port with positive V ( 5V or battery V ) I saw few sparks .. like a small short ?

With the resistor connected (and getting hot while the vehicle is running), measure the voltage and both ends of the resistor and report back the readings. i.e. meter on volts, put +ve end on one end of the resistor, negative to the body of the car, measure and write the number down. Do the same for the other end of the resistor. Report back the two readings.

A 7805 isn't a good idea, since it will drop 12V to 5V.... BUT when the alternator feeds 12V (or whatever into the field) it will back feed 12V into the 5V output of the regulator....

Anyhow, take measurements, report back..

cheers,
george.

 

[Tapage]

14.72 on the ignition side
14.44 on the alternator side

It didn't get that hot this time?

At batt as expected was 14.74 ( I assume some lost through car wiring)

Appreciate your time and effort helping me sort this out.

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[Tapage]

Kind of redneck testing methods

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[george_tlc]

Well, with 14.72V on one side and 14.44V on the other you're only dropping 0.3V approx. Assuming you're using a 20 ohm resistor you have

P = V x V / R

So P = 0.3 x 0.3 / 20 = 0.005W being dissipated in the resistor So it shouldn't get hot at all...

Of course that assumes DC on the alternator side, which it probably isn't given it's an alternator not a pure DC source.

Why not try a higher value resistor to see if it still excites the alternator (try around 100 ohms). A higher value resistor if it still excites (and I assume it will) will reduce initial power dissipation in the resistor.

Yes, very redneck wiring you have there

cheers,
george.

 

[Tapage]

Chat!

That was 22ohm 5 watts resistor I was trying to get around 500 ohm resistor ( read in another forum) or 3.5 watts bulb to recreate the hole charge light circuit.

What I don't get yet it's why the alt isn't regulating?

Which engine running lights on still charge at 14.7X range

But if I disconnect the resistor it stop charging

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[Bogo]

But if I disconnect the resistor it stop charging

Why do you expect it to continue charging if the resistor is disconnected?

To test the regulation. Put the head lights on for 10 minutes without the truck running. That should drain a few amps from the battery but not enough to keep it from starting. Start the truck, with the resistor hooked up, and see what happens to the battery voltage as well as the voltage across the resistor.

 

[george_tlc]

Tapage, if the alternator is putting out charge, it will be around 14.4V. Are you using a GOOD multimeter to measure the voltage across the battery terminals or some cheap junk??

The typical alternator regulator has NO idea if the battery is fully charged, so it will push 14.4V (nominal) out with enough RPM.

The sense wire from the alternator should be connected to the battery if you want reliable and accurate charging voltage. At low RPM most alternators don't put out much charge.

cheers,
george.

 

[Tapage]

Why do you expect it to continue charging if the resistor is disconnected?

Reading about GM alternators its my understanding they only need initial V to start charging then they will continue doing it just alone actually returning 12V on that exited port ( L port in my case)

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[Tapage]

With all lights on ( 4 100/90 bulbs)



Amps with that draw



Alternator side of the resistor engine running



Ignition side of the resistor



Fresh start low idle ( around 600 rpms) all lights off no resistor connected ( battery V )



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[retrofive]

(no real input here, but can't argue you are using a cheap meter)

 

[Bogo]

I say just keep the resistor connected to a switched source. It looks to be working.

BTW:: all my older John Deere tractors require the ignition switch to be on for them to charge the batteries. As soon as you turn the ignition off, the alternators quit charging. Depending on the tractor they are either standard off the shelf Bosch or Delco alternators made for car or truck use.

 

[Tapage]

Not sure how much are going to last my battery with almost 15V on them..

And just grab 500ohm 5w resistor to try this combination.

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[Tapage]

You guys know what is this? Found in my engine bay it used to have one wire connected (not any more) in the base

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[george_tlc]

Looks like a thumb and two fingers to me...



Why not google for 90980 04040 ??? Hint, it appears to be a capacitor 250V and probably 0.47uF

cheers,
george.

 

[Tapage]

well actually I did that .. but that does mean nothing to me .. EPC have it as

86-01: RADIO RECEIVER & AMPLIFIER & CONDENSER

but was on my engine bay ..

 

[george_tlc]

Keep googling.... Seems like it is used to 'save' the radio presets on some toyotas. Since it sits on the +12V line it could live in the engine bay.

cheers,
george.

 

[Bogo]

I bet it is for electrical noise suppression for the radio.

 

[Tapage]

Score!

V after 500ohm 5w resistor



Total V more reasonable? ( want to thing yes)



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[Tapage]

Few things still need my attention ..

Manage to identify the light ( cluster ) charge light in the harness .. ( plug ) but there is an interesting thing .. I can make it light on if I provide body ground .. but it does not light up with the L port coming from the alternator .. despite I test it ( test lamp ) and it have ground indeed when the alt it's not running ( as it should be ).

Not big deal .. just wonder why .. it seems like L wire from Alt while not running just past the V and not ground it ..

Well test it with all my light and winch .. and need to buy a smaller belt to tight that bitch much more ..

almost forgot ..

opinions about the best way to mount that resistor .. ? or maybe those frame mounted resistors like this one

http://www.ebay.com/itm/25-WATT-500...aultDomain_0&hash=item5639ed4d0d#ht_861wt_956

but then what I can expect from the watt increment ? coz that one I test was 5W and usually those frame mounted are 25W ..