can't figure this one out

[K-5krazy]

I have two batteries, and a 200 amperage alternator, which is brand new, but I can't listen to my radio with my lights on. Much less torn on my A.C. or K.C lights when I want to .What the heck. My truck can only run like one thing at the time. With my lights on the battery gauge jumps down to around 8 volts

 

[spearchucker]

Maybe you have corrosion on the inside of your battery cables, a bad ground or a loose belt on the alt. I'd suspect the first one though. With your headlights on or other load, measure the voltage drop from the battery to ground and then from the battery to the positive terminal on the fuse block inside the cab. You shouldn't have more than about 0.5V drop.

 

[ryoken]

Do you have grounds to both the body and motor?

 

[1979jimmy350]

are you sure that your alternator is putting out the full amount of amps, with the setup you have you shoudl have no problem running every thing that you are

 

[K-5krazy]

Yeah I do have grounds from my frame to the body, but my entire undercarriage, body and frame is sprayed with bedliner. Would this make a bad connection for the grounds

 

[neverendingproject]

Yeah I do have grounds from my frame to the body, but my entire undercarriage, body and frame is sprayed with bedliner. Would this make a bad connection for the grounds

Unless you scraped it away, it would make no connection.

 

[K-5krazy]

Well that is could be part of the problem then, At first the cable was grounded from the battery over to a header bolt on the engine, but that made the conection really hot, so i moved it over to the frame. (bedliner in the way opps!!) thanks for the advice. But when it was on the engine it still did not work properly.

 

[K-5krazy]

Yeah my alternator is fine. I had another 200 armperage alternator before this one, and ecountered the same problem. The Reason I put in 2 batteries and such a high amperage alternator was because of this problem. It did not help much.

 

[diesel4me]

wires??..

Did you upgrade the wiring from the alternator to the starter solenoid,and the other 10ga red wire going to the junction block??...if not,the 200 amp alternator may have roasted the original 10ga wires,which may have been gangerene already just from age...

Those wires have the fusible links in them too,if any are blown or "half" blown,it won't let any charge get back to the battery(s)...if its charging period!..have you tested the voltage with the engine running ,with a meter other than the stock one,to see exactly what voltage its putting out?...

 

[K-5krazy]

What gauge wires do you recommend that I use, and no I did not replace any of the old wires except for the wire going from the alternator to the baterry.

 

[diesel4me]

thicker!...

You'll need at least 8 gauge wire,if not larger,to handle the full amperage your alternator is capeable of producing.....some guys use 4 gauge battery cable wire,but its kind of hard to join it to the existing wires,since its so thick..overkill is good where wiring is concerned,many trucks burn when the old wiring gets too hot...

I'd try and test the voltage,and make sure the alternator is charging,before replacing the wiring..make sure the wires on the small plug both have 12V when its running,otherwise it wont charge due to lack of feild current to "excite" the alternator..--it needs current to make current!--12v has to go in ,before 14v will come out...

 

[K-5krazy]

THanks for all your help, i did toast a wire. Great advice