bad batteries

[allformike]

my batteries read 12.50 v useing my meter, but cranks over very slowly in the morning, or after sitting a few hours, sometimes it won't evan crank over. i had to jump it 2 days ago, now i drove up town, shut it off, when out to leave a hour later and low it won't start. the meater says 12.34 and no start. do i need new batteries?

[BigGun J]

Watch the voltage on the batteries when you crank it over. The voltage will most likely drop to -8 volts. If you can get it running you should see 14 plus volts at a high idel. Bad batteries can show 12 volts static but not hold that under load. Any battery shop will test your system.

Good luck, Jim

[Subzilla]

Not to insult but make sure you check your connections for tightness.

I was up on the Virginia mountains last January. 15 degrees out. Went out to start the Blazer, turned the key and nothing. Paniced. Popped the hood, started wiggling connections and found one battery with a loose connection. Tightened it and varroooom.

Also, get rid of the factory "3 thread" bolt connections and put on with the Dr. Lee battery connection mod. This is basically substituting with 5/16"(?) bolts and nuts in place of the factory bolts. Screw in the longer bolts almost bottoming out, then make the connections tight with a nut between the bolt head and the cable connection. Do a search for this to see pictures and better explanation.

Hope this helps.

[Robyn]

Depending on the year of the truck the crossover cable can be bad and this will only give you one battery for starting.
The cable issue cant be stressed enough. Batteries do go away and it sounds as though you may have one or both leaving you.

The only realy good way to be sure is to have the batteries tested with a load tester that places a hard load on them using a carbon pile.
One battery with a dead cell will take the whole system down.

Once the system is up and running you should see 14.2 to 14.5V at both batteries.
Ground cables as well as the + can and do go bad.
The Dr Lee fix is a good one. The only thing better is to toss the side terminal stuff and rerplace it with good heavy welding cable with totally soldered on "eye" ends and use good jello batteries with bolt on terminals.

Best
Robyn

[allformike]

i had them tested this morning and they were both bad, got a couple red top optimas and changed my wires from side to top post mount. it cranks over really nice now, also had the alternator tested and it was great. my wallet thanks the guy at murry's for the good news.