The Stovebolt Site Forums The Shop Area The Electrical Bay Battery drain starting engine

I have a 54 3100 with original 235. The only modifications to the original set up is a 12v conversion with alternator. I had original posted about an issue starting after the truck had sit for several days. I resolved that issue. Sort of.

Original Post

When I try to start the truck I have to crank it for a while to get the gas back into the system. After about only 5-10 seconds of cranking the engine the battery starts draining very quickly and within 10-15 seconds it has drained to a point it will not turn the engine over. I have tested and confirmed I don't have anything draining the battery while it is sitting. When I first start cranking the engine it spins it at high RPMs. Does the old 6v starter put that much strain on a 12v battery? Even though the battery appears to be holding a charge do I have a bad battery. It is only about 5-6 months old. Once I finally get the truck started, the alternator brings the battery right back up to full charge. I can just tap the starter and the truck fires right up. As long as the truck is started daily it fires right up with no battery issue. The part that could be deceiving is as long as the truck is started and I keep gas in the system it only takes 2-3 seconds of cranking to start the engine.

Also, the way I normally get it started when it has been sitting for a while is to make sure the battery is fully charged plus I have my battery charger connected and flip on the jump start feature (50 amps) to provide some additional support in cranking the engine. If it takes too long for the engine to turn over my battery charger will start to smoke from drawing some much current and I have to stop right away to let it cool off before I try again.

Your battery is probably "sulfated". It can deliver a short, high current burst of energy, but it has no reserve capacity. Without a pretty sophisticated carbon pile load tester it's not possible to do an accurate test, but here's a field expedient work-around that I've used pretty successfully. Disable the ignition by pulling the coil wire out of the distributor cap and grounding it (or just don't turn the ignition switch on with a stomp start) and spin the starter for 15 seconds. Have a helper hold a set of voltmeter leads on the battery posts (not the terminals) during the test. At the end of 15 seconds with the starter still turning, the terminal voltage should be above 9.5 volts. If not, replace the battery.

There's a recovery method for a sulfated battery if you're willing to go to the effort, but it's a lengthy procedure with only about a 50% chance of success.
Jerry

I am assuming you have cleaned ALL the terminals and connections to ground/starter. You may have gotten a bad battery. You need to do a load test, I'm sure HRL will be happy to explain the process again.

Thanks. I did not know there was such a thing as "sulfated". The battery is still under warranty but it sounds like the difficulty in testing for this will make it hard to get Wally World to honor the warranty. I will test it. Thanks again.

A battery that doesn't get cycled frequently, or is left in a discharged condition for a long period of time forms crystals of lead sulfate on the plates. That's not normal, as the spongy lead sulfate that forms during normal discharge recombines into the acid easily when the battery is recharged. Sulfate crystals are extremely hard to re-dissolve and they reduce the reserve capacity of the battery by weakening the acid concentration. A sulfated battery absolutely will not pass a high-discharge load test.
Jerry

Walmart tested the battery. It tested bad. That is the good news. The bad news? I am two weeks outside the warranty, which is my fault for not doing something sooner. At least now I know what the problem was and I learned something new. Word of the day - "sulfated"

After reading all of this I think my brand new 6 volt battery may be sulfated. It cranks ok with charger hooked up but without charger it cranks a few seconds then fades away. battery reads 6.5 volts when not under load. I have a new starter, new #2 cables with ground attached to clean bare metal point on bellhousing near starter. If I conduct the 15 second cranking test how many volts should a 6 volt read?

Jim

After 15 seconds of cranking with the ignition disabled, a good 6V battery should be at 4.5 volts or slightly above, while the cranking load is still on the battery. Have a helper push the starter pedal while you hold a set of voltmeter leads directly on the battery posts- - - -NOT the terminals bolted to the posts!
Jerry

Thanks Jerry