Charging issues.

kc5dlo · Jan 28, 2016

I recently purchased a Case 570LXT and while going over it waiting for the ground to dry a little, my neighbor and I noticed that when the tractor is first started, the tach does not register and the voltage stays at battery voltage. A blip of the throttle will get it to charging. Neighbor suggested changing the alternator. Found a new one cheap enough and bought it. We put it on last night and it wont charge at all.

The alternator is a Bosch type with a B+ terminal, a smaller D+ terminal and a spade connector for the tach. While looking online for the alternator, I came across a post that someone pointed out that the alternator light is what energizes these alternators and I don't see an alternator light on the dash. The lens on the dash needs replacing or polishing to see better but I don't know if there is an alternator light on this or not. There is an oil pressure light that is working and comes on when the key is turned on and goes off as soon as the engine starts. Tried taking the new alternator to AutoZone and O'Reilley's last night bot the people at both places looked like they saw a ghost when I told them the alternator was for a tractor and said they could not test it.

Worst case is I could live with knowing that I need to give the throttle a blip after starting to get the charging going but thought I would ask here about the alternator light and anything else I might be missing.

Steve

davesl708 · Jan 28, 2016

Is the idle set at the correct speed?
Auto stores are notorious for hiring bots. If it doesn't say car/truck the paralysis sets in. They should not have had any problem testing your alternator.

kc5dlo · Jan 28, 2016

As I recall, the idle is a little under 1000 as indicated by the tach. Revving to about 1500 is enough to get it to start charging.

Dave M7040 · Jan 28, 2016

I did a little reading and found this explanation which may explain why your original alternator did not turn on until the engine was rev'd.

In the Bosch system, the size of the charge warning lamp bulb is critical. Too low a wattage bulb will not supply enotugh field current for "bootstrap" operation to be reliable. The Bosch book that I have states that the lamps must be at least 2 watts for 12 volt systems. If you have replaced your charge warning lamp recently, then too small a lamp may be your culprit.

It sure sounds like your tractor must have a light if it originally came with a bosch alternator.

Dave M7040

Steave · Jan 28, 2016

Go with what Dave M7040 said. It sounds like the old alternator is working properly and having to rev up the engine is common IF the indicator bulb is not hooked up or is simply a bad bulb. Maybe work your way down to the light bulb and replace it with one you know is good. When you turn the switch on it and the oil indicator bulb should light up then should of course go off if everything is working after crank up.

kc5dlo · Jan 28, 2016

I am more convinced I have a non working Warning light to find and troubleshoot. I wonder if it would have anything to do with the new alternator not providing any power? Perhaps less sensitive to the engine revving?

Just looked closer at the parts list and I see there are 8 - No. 168 bulbs and 3- No. 194 bulbs in the instrument cluster. I think I will try opening up the panel and try swapping in some new bulbs.

Steave · Jan 28, 2016

The #168 bulbs are 3 watt and probably used for illumination bulbs as they are indirect lighting just behind the cluster. The #194 bulbs are 2 watt and would probably be used for the indicators and be located just under the lens.

Hopefully the only reason it's not working properly.

skyhook · Jan 29, 2016

Just curious, when you give it that " shot" of throttle and it starts to charge, what is the charging voltage? Here's what I'd do, check the fan belt to make sure its good and tight,,check your battery connections and make sure their clean and good and tight,, take a battery booster cable and connect it to the negative battery post and connect the other end to an engine ground, (see if this effects the charging for the better) if not, take the ground cable from the engine and connect to your cab or a good ground near your dash panel. Sometimes a bad ground will produce this "late wake up call" also.

Dave M7040 · Jan 29, 2016

Internal regulators electronics can start to fail and leak enough current internally to bootstrap the alternator into charging.
There are companies who make an internal regulator for GM or Delco Remy alternators where the replacement regulator is designed to leak enough to start the charging without a light circuit.
Perhaps your old original alternator was leaking enough current to kick itself on whereas the replacement one's regulator is not leaking current into the field winding.
I have created a charging system light using a clearance light from a trailer. If the old light and wiring is corroded or confusing take this route.
You just have to open up the clearance lamp and remove the ground connection to the mounting bolt and solder on a second wire to use in the new install.
Dave m7040