Hey Y'all,

I've got an '84 B250 w/355,000 mi. and a 318. Rarely ever have a problem. However what's been happening is : I start it up, charge VERY SLOWLY increases to about 14v. With engine at cruising speed; turn on my headlights; charge still at 14v. With engine at idle; turn on my headlights; no more charge into the battery. If I continue to drive this way; battery discharges to where it won't start vehicle. I've changed the alternator, regulator, and Advance Auto tells me the battery's good. Help ! Thanx.

 

i would assume that the voltage regulator would be external on that, mounted somewhere on the firewall. I prefer using ford regulators because they work better imo. I would check all connections.

i had a similar problem, i just wired up a switched power from ignition to the reg, power from alternator to reg, field power from alt to reg, other post on alt to chassis ground. Thats if its set up like that.

IDK, i jerry rig crap to save some $$. only thing i can suggest if theres no drain on the battery when its off. But im sure someone else here could help you out more than me.

 

What you describe is all too common. Basically there is too much resistance in the charging circuit. While the voltage is regulated by the voltage regulator, the amperage is controlled by the battery and how thirsty it is for amperage. With 26 year old wiring leading from alternator through dashboard ammeter, and multiple connectors in between as well as a fusible link, well it would be like trying to breathe through a cocktail straw after you ran 4 flights of stairs.

Every connection causes resistance and voltage drop, therefor less amperage is making it to and through the battery to power your accessories.

You should upgrade the wiring. This includes the grounds from the battery to engine. battery to firewall, and engine to frame and alternator to engine. You might just want to remove and clean all of these, and inspect them for corrosion. This might actually solve your problem. You can also run another wire right from the alternator to the battery positive This should be fused with a fusible link 4 awg sizes smaller than the cable you run.

I live off of 12 volts. I have a battery monitor and 3 batteries, and I can tell you the stock charging circuits were barely adequate to recharge 1 engine battery. Serious upgrading of wiring in my situation is critical, but on yours, unless you use a lot with a huge stereo and lights deplete the battery just sitting, you just need to widen some of the bottlenecks, by cleaning all the conections, especially all the grounds you can find.

Consider also removing the dashboard Ammeter from the loop. A simple voltmeter will give you the same information as to whether the alternator is working, without restricting current flow.

Read and learn:
http://www.aa1car.com/library/charging_checks.htm

http://www.alternatorparts.com/FAQ.htm

 

Thanks for your suggestions guys.... I did fix it, but I feel a wee bit embarrassed.... The problem turned out to be a loose belt ! It wasn't evident it was slipping until increasing RPM's and the inability to charge the battery was displayed before that. Also I don't use a second belt (on the alt./AC/crank pulleys) because I don't run AC. Anyway, mystery solved !

 

Oh yeah, of course. I meant to suggest the belt was slipping, instead of going off on a rant about the piddle poor charging systems.

I also only use one belt.

But you might find, with the headlights on, and blower motor on high, at idle, the voltage will drop below 12.8 because the alternator, when warm, cannot produce enough amps at idle, and the battery is supplying the rest.

 

Yep, I might end up installing a second belt. But in order to get it on, I'd have to remove the power steering pump belt, which causes coolant to leak. Nice design, huh ? I've adjusted or replaced that pump belt a few times, and am wondering if I fool with it too much, could I cause a permanent coolant leak ?