New Alternator on Yuchai YCT306S Bulldozer

[timbatrader]

I have replaced the old alternator and charge controller on my dozer with a "one wire" alternator which requires a current through the "charge light" to excite the alternator to make it work it seems difficult to find a little light bulb charge light to put on the dash they are all LED these days I worry that the very small current that will go through a LED will not be enough to excite the alternator My question is
1 will may charge circuit work using a LED charge light
2 If its not going to work I see it is common when converting car indicators to LED to include a resistor in parallel to the LED to trick the pulser into thinking it has a bulb in the circuit will this same resistor value work for my charge circuit

 

[aesmith]

My guess is that an LED won't provide nearly enough current to get the alternator going, normally a warning light would be around 3W or 5W. You will be able to see because the light will stay on. If it's marginal you may find that raising the revs a bit will put out the light. The "ballast" resistor intended for LED indicators would pass much more current than you'd need since they're intended to simulate the load of a pair of 21W bulbs. At a guess you'd want something like a 47ohm resistor, which would be equivalent to a 3W bulb. By the way if the current i sjust slightly too low, you may find the alternator fires up when you give the engine a few revs. Our digger is like that, the warning light doesn't go out until I blip the throttle to around 800rpm, then after that it continues to charge even at tickover.

 

[timbatrader]

Thanks Aesmith thats just the information I were looking for now to find 47 ohm resister

 

[aesmith]

Something like this .. 47 Ohm 5w 5 Watt 5% Ceramic Cement Power Resistor (3 Pieces) | eBay

By the way, the reason I said 47 ohm rather than say 50 or 45 is that 47 is one of the so-called "preferred values".

 

[Dave M7040]

Far better and much simpler to abandon the old charge light warning system.

Use a $10 voltage display which shows battery voltage completely independent of alternator.

Although it is too late for you, I will mention the Denso one wire alternators sold in many ratings. 35 amps is $56. They are much smaller than the Delco's so easier to fit unto existing machinery.

.
These are the type of voltage display on ebay.com
DC 12-24V Waterproof Car Motorcycle LED Voltage Meter Digital Display Voltmeter | eBay

If you want fast delivery, look for ones that are already in the USA. Same product and you pay a few dollars more for quick delivery.

Just leave the jumper on your Delco all the time to "turn on" the charging. Forget bulbs and resistors.

The one wire Denso does not require any fooling around. Fyi GM is now using Denso alternators on many car lines including Buick.

NEW ALTERNATOR CHEVY MINI DENSO STREET ROD 1-WIRE 35 AMP 4��-52�62 1218�-SE | eBay

Many tractor owners have followed my suggestion and reported back being exceedingly pleased.
The voltage display also gives them a good indication of the condition of their battery as they can see the voltage while engine is cranking.

Dave M7040

 

[aesmith]

Far better and much simpler to abandon the old charge light warning system.

Without the warning light or equivalent, his alternator won't start charging. Well I guess it might when the engine's revved high enough, but for proper function it needs the light.

By the way, can those single wire alternators be permanently connected to the battery live? I've often wanted to work out a system that didn't need an "on" switch, for tractor, digger.

 

[Dave M7040]

Without the warning light or equivalent, his alternator won't start charging. Well I guess it might when the engine's revved high enough, but for proper function it needs the light.

By the way, can those single wire alternators be permanently connected to the battery live? I've often wanted to work out a system that didn't need an "on" switch, for tractor, digger.

If you put a jumper from the main Delco + post to one of the two small terminals ( I forget which one right now) then it will always start and charge using its internal voltage regulator.

With the Denso, one heavy gauge wire from its output terminal to the starter solenoid ( or battery) and you are finished.

Dave M7040

 

[aesmith]

If you put a jumper from the main Delco + post to one of the two small terminals ( I forget which one right now) then it will always start and charge using its internal voltage regulator.

Won't that run the battery down when the vehicle's left? If it needs to be switched I can't see the benefit over using a warning light which has the side effect of reminding you to switch off. I'm more familiar with Lucas alternators so possibly Delco might be different, but if the terminal is intended for the warning light then it must pretty much by definition draw current. The other small terminal on the Delco looks to be a remote sensing connection.

 

[Dave M7040]

You need to understand how the light works. When the key is on but the engine is not running, the bulb gets its ground through the alternator's internal regulator and illuminates. As soon as the engine starts and the alternator has output, now the bulb has 12 volts + on both its terminals and their is no current path and the bulb is off. There is no current flow unless you turn the key on with the engine off.

Think of the DELCO alternators on vehicles with an ammeter and no light. A Corvette being one example. It is not running down the battery when not running and turns on with no problem.

If we talk about cars or light trucks, there are many small current drawing circuits on all the time. Clock in the radio, engine computer to respond to a remote start, door unlock fob.
The battery can withstand a parasitic draw for months.

Some people feel the remote voltage sensing is a critical function. It becomes appropriate when there is a large constant current draw in the vehicle, air conditioning, electric rear window etc.
If the wire from the alternator to the battery and the battery to the main fuse block is carrying a lot of current all the time, there will be voltage drops occurring in the wire which the alternator cannot see unless it has a dedicated voltage signal i.e. remote sensing.

On many tractors, motorcycles, garden tractors, battery charging is done by a dynamo not an alternator. The dynamo, using permanent magnets (PM) instead of a controllable magnetic field, puts out an alternating current at around 40 volts AC. Not unlike a regular alternator. With the dynamo, the AC output goes to an external not internal rectifier. The rectifier incorporates a Zener diode. If you are not familiar with Zener Diodes, they are designed to turn on at a design voltage and in doing so turns any voltage in excess of a set level into heat. It is completely dumb. There is no remote voltage sensing.

The fins on this rectifier are to dispose of the excess heat.

Note the circled Zener diode in the internal circuitry.

With the voltage display sensors I suggest owners use, they draw so little current they have no effect on the battery for weeks if not more. You can wire them to be on all the time or, as some owners do, have them supplied by the key switch when it is in the ON position so it serves as a reminder the key was left on.

Few owners can successfully diagnose and fix complicated charging systems. The most modern complicated ones use a computer bus to control the alternator. This system is beyond all but a few trained individual's understanding.

The One wire Denso and voltage indicator are a system most owner's can successfully get working.

Dave M7040

 

[aesmith]

You need to understand how the light works. When the key is on but the engine is not running, the bulb gets its ground through the alternator's internal regulator and illuminates. As soon as the engine starts and the alternator has output, now the bulb has 12 volts + on both its terminals and their is no current path and the bulb is off. There is no current flow unless you turn the key on with the engine off.

I was referring to your post where you suggested jumping the two connections together, unless I misunderstood then that implies permanent connection whether the key is on or off. Even if it only draws the equivalent to the warning light current that would still run the battery down quicker than I'd like. As I found out first hand when I accidentally left the digger switched on. That's why I was interested in a system which doesn't rely on an on/off switch. Lots of older machines were built originally with dynamos and simply don't have an On position for the key switch so to run a conventional alternator you need a switched supply.

Think of the DELCO alternators on vehicles with an ammeter and no light. A Corvette being one example. It is not running down the battery when not running and turns on with no problem.

Would have to see the wiring schematic to comment, but I suspect the ignition switch disconnects the exciter connection.

If we talk about cars or light trucks, there are many small current drawing circuits on all the time. Clock in the radio, engine computer to respond to a remote start, door unlock fob.
The battery can withstand a parasitic draw for months.

Our modern Land Rover with all it's computers has a quiescent current of 26mA. On the tractor and the digger it's too low to register on my meter (if I've remembered to switch off)