I am hoping someone can help me with a potential problem. I am running a 1996 F-250 Extended Cab truck. It has the 5.8L (351W engine) in it. I have a 7.5ft Meyer blade on the front. I have started the truck and exercised the blade roughly once a week for the last month. I have done this from a park / idle position. Today, I was taking the truck to the house of the guy who will be driving the truck during storms and when I was getting ready to turn into his drive way, I turned the blade to a straight position. Here is the problem the amp gauge went from a normal position to the lowest position (8) and almost died. When I operate the blade in a park / idle state the motor is fine, the amp gauge is fine there are no problems. Anyone have any ideas what might cause this. I am thinking the Alternator might not be producing enough amps but I am not sure that really makes sense, but that is the only thing that seems possible. I drive a 1992 F-250 for plowing and my amp gauge moves around when I am using the blade, but it normally jumps up no goes down. Any help would be greatly appreciated. Thanks in advance.

 

I am not the one with an answer. However, the battery should read at least 12 Volts when the engine is OFF and as least 14.2 when the engine is running.

You could start troubleshooting with this.

Take care

Boon

P.S. Check the electrolyte levels in your battery while your at it. Even on most sealed batteries you can remove the covers and use only distilled water to fill each cell if necessary.

 

There's a few things you can do to figure out what's going on. Generally, idle speed is a little higher in park than in gear, that will lessen alternator output slightly.

As boon mentioned, check your voltage with the truck running, at the battery, while idling and operating the plow.

Check ALL cables and connections for corrosion and frayed wiring.

If the truck has the 95 amp alternator, you can easily upgrade to a 130 amp alternator. It's a bolt-in deal, but you'll have to upgrade your charge cable to 2 ga, and add in a 175a megafuse.

 

My 1994 460 with a 130amp alternator from the factory uses only a 6 ga wire with a 12 ga fuse link in the line. Then two 12 ga wires to the starter relay.



/

 

6 ga is acceptable in a DC application to about 70-80 amps.

My 95 that had the original 95a alternator also had a 6 ga charge cable. I figured since I was upgrading anyway, I may as well upgrade to a proper size cable and fuse.

 

The prints show a 1995 with a 95 amp alternator using a 8 ga wire into a 12 ga fuse link.
The only one with a 2 ga in that spot is the Ambulance wiring.

I am just saying how they were wired from the factory so if he wants 2 ga he will not find it in a salvage yard.

 

The issue is the duration of the high amperage output. Most vehicles only put out high amperage for a comparatively short period of time, just enough to replace the starting draw and possibly some drain from accessory use while the engine was off. Therefore vehicle manufacturers put undersized wiring in. If you consume large quantities of current over a prolonged period of time you risk melting the insulation. The problem is most pronounced in areas of sharp bends in the cable where the conductors will migrate through the softened insulation.

Ambulances and other emergency vehicles are wired with 2ga because they have constant high current demands. If your plow rig is using 12 volts (I've never seen how they are set up) and you are regularly shift the blade and raising and lowering, then I would recommend increasing the wire size as well.

The other issue to deal with is voltage drop. The higher the current demands the greater the voltage drop for a given wire size. Think of it as water flowing through a pipe. For a given water pressure, the smaller the pipe diameter the less water will flow through it.

Boon's suggestion to check battery voltage is also a good thing, but should be carried further. A battery nearing end of life may still show a resting (no load or charge for 15-20 minutes) voltage of 12.6 volts, but be unable to sustain a load. Have your battery tested for load capacity.

Think of a battery as a reservoir between a mountain stream and the pipes in your house. Stream is your alternator, reservoir is your battery, the pipes in your house are the wires in your truck, and your voltage gauge shows the water level in the reservoir. If you draw water out of the reservoir faster than the stream can replace it, then the level in the reservoir drops. When you stop using water the stream replenishes the reservoir. Now image that the reservoir is rusty and full of holes. The stream may still be able to keep the reservoir full, but between the leaks and the usage in the house the reservoir level drops considerably faster when you turn on the water.

Hope this helps.

 

Hello and good afternoon Island Time.

An excellent metaphor for explaining voltage, wiring and alternator!!!!

Using a combination of technical and laymans terms even I could understand it; I am a Rookie so this is very helpful to me.

Thanks and take care!

Boon

P.S. One day I was walking my dog and stopped by the EMT garage and asked them how they could power so many lights, etcetera. They told me that the Trucks have 2 alternators and dual batteries.

 

Yup, and a high idle control circuit as well. When you set the parking brake with the engine running it bumps the idle up so the alternator(s) have greater output.