Q2 Battery Terminal corrosion

’49 8N front mount 6V

I don’t get to visit my tractor remotely as often as I want so it goes a while between uses. I’m in western (damp) Washington, yep the part that was underwater last week. Muddy mess out in the fields.

Every time I go to start “Francine” after 3-4 weeks I find I have to take off the ground terminal and clean the clamp and the post. Every time! And always the positive ground, never the other terminal.

Other odd part is that when I first press the starter button it spins the engine. I can do this 2 or 3 time and then it stops. No slow turning no nothing. Get the handy dandy Fluke out (I am an electrical engineer) and yep, 5.5V on the battery .2 on the terminal under load. Put a battery charger on the terminals and it reads charged, move the clip to the positive post and it reads ¾ discharged.

Clean the post and she spins, charge the battery to ½ and she fires.

Any clues. I really do know a lot about electronics, but what little I know about tractor/auto shop stuff comes from this board. Kirchoff is always right but fixing things from first principals is a bit slow…..

If the terminals are anything other than clean, shiny "lead to lead", sometimes they will make a connection, sometimes not.

Also, a poor connection can develop INSIDE the battery cable end, between the lead end and the copper cable inside. The same "semiconductor" sometimes it conducts and sometimes it doesn't scenario holds true there, too.

Also, the battery may be weak, and "on it's way out" (load amp-hour capacity). A poor connection can develop INSIDE the battery, too, at one of the joints where the internal lead "bus bars" join the individual cells together. Sometimes, when a battery explodes, the theory is that a poor INTERNAL connection sparked off the hydrogen gas inside.