battery problems

[veganxxx]

I have an 88 f350 that I'm working with. The problem is that the batteries die even after a drive and even if they don't die all the way the truck has a real hard time starting. There's a new alternator, new starter, one new battery, one battery two years old, and I took off the vehicles grounds and cleaned them as well as the terminals. It seems like something is draining power. I tested all the glow plugs and replaced the one bad one. Any ideas?
Thanks

[siegler]

Is the 'charging system' light on? (looks like a bttery symbol on the dash)

Do you have continuity between the alternator output stud and the positive battery terminal? Between the alternator case and the negative battery post?

If all the above is fine then disconnect the positive clamps on both batteries and test for a parasitic drain (multimeter set to amps with one test lead on the positive battery post and the other on the positive battery clamp). If you get a reading over a couple tenths on an amp (excluding hood light) then there is something in the system drawing more current than it should when the truck is shut down. Pulling fuses one at a time under the dash board might be a good place to start if that's the case.

Hope that helps.

-Andrew

[drinkypoo]

Originally Posted by veganxxx

I have an 88 f350 that I'm working with. The problem is that the batteries die even after a drive and even if they don't die all the way the truck has a real hard time starting.

"hard starting" is one problem, "batteries drain" is another, both may be related to the starter itself of course. If the starter doesn't turn "too fast to count revolutions" then something is out of spec. But first, do a battery test. Disconnect the cables and let the batteries sit for half an hour. Check the battery volts, which should be over 12; if they are not, charge the batteries, let them sit half an hour, and repeat until they are over 12 (12.6 is a "fully charged" battery) or you give up and decide the batteries are bad. A good charging voltage is 1.5 to 2 volts over battery voltage. Also test for AC volts across the battery terminals, if you get more than 20mV then your diode pack is bad. If your battery is not charging then you probably have a bad alternator or regulator.

Try disconnecting the voltage regulator overnight to see if your batteries are still drained. Also the starter relay. If that doesn't help you need to play investigator with a trouble light or ammeter between one battery (the right-hand one) and the clamp, and pull fuses/relays until it goes out. Fun times.

[veganxxx]

It seems like the issue was the terminals on one of the batteries did not have continuance to the poles. I scraped both clean and the starter wizzed away at a good speed. Thanks for the suggestions. I didn't think about the terminal corrosion at first because the terminals aren't that old. Thanks for the suggestions good to know for the future.

[drinkypoo]

Originally Posted by veganxxx

It seems like the issue was the terminals on one of the batteries did not have continuance to the poles. I scraped both clean and the starter wizzed away at a good speed. Thanks for the suggestions. I didn't think about the terminal corrosion at first because the terminals aren't that old. Thanks for the suggestions good to know for the future.

Next time I need batteries I'm buying the kind with posts, cutting off the terminals, and soldering on copper lugs. These trucks shake way too much for lead clamps. If you continue to have these problems check your grounds, bad grounds lead to corrosion in unfortunate places.