My 78 f250 CC has been rough on batteries. Only get about a year and a half out of them. I don’t drive it much except as a camper toter in the summer and trips to the dump. My DD is in the shop so the crew cab is it. I noticed that I’m charging at 14.7 volts. Depending on what you read this is ok or too high.
Could the regulator be bad and need replacement?

 

I believe that’s about average while running.

 

No, 14.7 isn't "too high", that's right in there. Proper charging voltage actually depends on the temperature. If it's 105° that's too high, but let's say it's -5° below zero, not too much chargin' goin' on there. All the voltage numbers you read about are "normalized" for a "standard temperature" of 77° F. Mostly this is automatic, the voltage regulator set point takes all this into account. But it's something to keep in mind.

Measuring at idle, with no accessories running is one thing, but what you want to do is spool up the RPM to around 2000 or so - like running down the highway - and then really load up the alternator by turning on the headlights and heater on HI, crank up the radio, maybe run the wipers. Now measure the voltage right on the two battery posts. It will sag down some, but it should be well above normal open circuit battery voltage. 13.8 to 14.2 is considered "normal" at idle with no accessories running. Clear as mud, right?

Batteries that sit idle for a while tend to lose their charge and the plates will sulfate up permanently. A battery tender or periodic boost charging will help extend battery life quite a bit, a good external battery charger will pay for itself quickly. Your alternator will thank you, too. Chronic under charging kills most batteries, not a slight overcharge anyway.

One thing ratty old battery cables and corroded grounds do, it "fools" the regulator into thinking the battery is fully charged, when it isn't.

 

Great reply Tedster9. Thanks. FWIW I have a Bluetooth radio transmitter so I can talk hands free. It plugs into the cigarette lighter. It will read voltage. Don’t know if it’s same as right across the battery. The 14.7 volts was with lights, wipers, radio and heater on full blast truckin down the freeway at 75mph.

 

I forgot to mention that I have a intermittent hot start issue. After a drive and everything gets good and heat soaked, stop for gas or a cold beverage and get ready to go and battery is dead. It has tested out twice as bad. Every so often it slow cranks but does fire.

 

The battery tested bad? How/who was/did the testing?

If anything the ciggie lighter output tends to read slightly low typically. It won't measure any higher anyway. What temperature we talking?

External regulators (if equipped) need to "see" a good solid reference to ground, at the same potential as the battery and alternator, if regulator is lifted electrically they can get wonky. The hot start problem can be an engine starter that's pooched, though undersized or el-cheapo cables and corroded grounds and connections (again) don't help one bit.

Basically if any of the battery/start/solenoid/ground/frame cables are original or even just kinda old they should always be replaced. When starters get long in the tooth (or those junk krylon part store "rebuilds") they soak up all the battery juice especially when engine is hot. Can try banging on the case with a hammer? If it turns over, that points to a starter that needs replacing, or rebuilding. Frame, firewall, and block all tie together and connections need to be clean and tight. Then it won't need further attention.

 

I went through this exact issue last year and took the advice from several members and ended up replacing my grounds which were all corroded and falling apart. I really think it helped. Soon after had to replace my alternator which in my opinion contributed to the issue. Here’s the thread.
https://www.ford-trucks.com/forums/1...locations.html

 

14.7 at idle doesnt mean anything. Keep the meter on it while revving the engine. The voltage should never go above 15volts. If it does your regulator is bad

 

Auto parts store guy tested the last 2 batteries as bad. Took them both back to the battery shop where I bought them. They replaced for next to nothing. I got a stack of them on the bench now that I rotate the trickle charger on to attempt to keep them fresh. I have a 429 with dove heads and a fresh rebuild. I run a custom curved dizzy and a 160 Tstat. I installed new cables and grounds a few years back. The starter is fresh and the alternator is only a couple years old. I know that doesn’t really mean anything with the crap rebuilds at the parts store.

 

Hot start trouble, first check the starter current draw. Normally a serviceable starter might pull 100 or 150 amperes. Check the manual for your particular application. The slick way to test this is with one of those fancy pants inductive clamp on ammeters around a battery cable. A defective starter will exceed spec by quite a lot. This will also tend to starve the ignition output too, making for difficult starts. If you have a carbon pile battery load tester, this can be used to check starter draw too.