The Stovebolt Site Forums The Shop Area The Electrical Bay Check your connections......

.......more often than I have.

Installing a battery disconnect switch today, I opened the battery compartment lid and started my plan of attack. Grabbed the negative cable and immediately noticed the cable terminal was very loose on the battery's negative post. I mean extremely loose. I was able to pull up on the terminal and it came right off of the battery post.

I am extremely surprised that I have,,, up to now, never had a electrical problem, especially during fire up.

So please learn from me, to dedicate some time to check your connections, etc. This could easily refer also to the brake, fuel & other parts of your truck.

Craig

Back when I was teaching a 2-year auto mechanics course at a state trade school, one of my students brought his mother's Buick Electra into the shop. It had a 455 engine with a chronic hot start problem. Several shops around town had replaced the battery twice, the alternator three times, and the starter once. The symptoms remained the same- - - -good starting when cold, but slow cranking and/or no start once the engine warmed up. After a 2-hour cool down, the engine would start again. I coached the kid through a "series resistance" test, where the voltage drop across every connection in the starting circuit was measured while cranking the engine with the ignition disabled. Good results- - - -at least until we got to the connection where the battery ground cable was bolted to the engine block. That loose, dirty connection was dropping almost a full volt! 1/10 volt drop at a ground connection is considered to be "acceptable". 5 minutes' work with a wire brush and a new bolt solved the problem.
Jerry

Why was that grungy ground connection prone to fail when the engine was hot?

A hot engine needs more amps to crank it because clearances such as pistons and bearings tighten up. The connection could barely carry enough current to crank when cold. the starter couldn't spin the warmed-up engine fast enough to kick it off.
Jerry

Ah , thanks.

cmayna Do you think those red and green felt collars for your top post battery terminals work ?? Some batteries seem to stay clean,others just get a dark resistive look that needs a good cleaning. First saw those felts in 70 never did actually use them and monitor it to see if they helped. Back then some would put gun grease on the cleaned terminals I guess to keep air away from them,this was on the farm !!

I have those felt collars sitting in my auto electrical parts box, but never used them. Maybe it's time to get off my backside.......

Anybody ever glue pennies on top of the battery by the terminals? For some reason the
pennies would corrode instead of the terminals e

Wheel bearing grease or Vaseline works better than all the gimmicks to minimize battery cable terminal corrosion- - - -just be sure to get the connections clean and tight BEFORE slathering on the grease. Whatever is used, it attempts to keep corrosive vapors away from the connectors. Sealed top batteries that don't vent gases near the battery posts do more to minimize terminal corrosion than anything else.
Jerry

You don't have to glue them. Just lay them on top. It works.

Another reason why a hot start challenges electrical connections is that heat increases resistance in a circuit. And the heat may not be directly from the engine itself, but rather from heat generated at the poor connection. Your connection starts out marginal and while running you go from bad to worse.
Kent