Battery issues

More specific symptoms would be helpful. Does the brand new battery twirl the starter right over, and slowly get worse and worse? What brand and WHAT RATINGS of battery (cold crank amps/ amp-hour rating) and what is your engine build? A slant six needs far less starter than a 10:1 compression 440. Do you live on a really rough road? Are the batteries properly strapped down?




Either you have real bad luck with batteries, or you have an electrical problem

Some of them could be:

You have a drain in the car causing discharge when parked.

You have a charging system problem, and the alternator is not charging the battery

You have some wiring/ connection/ starter issue which is using way too much juice to start the car, or a cable/ bad starter that is masking the true problem

To start, first disconnect the ground cable of the battery with EVERYTHING shut off in the car. You might spend some time thinking and looking---is there some courtesy/ map/ trunk lamp "stuck on?"

Take a parts store 12V test lamp and put it in series with the disconnected battery cable. If it lights and stays lit, you have a drain you'll have to find.

IF that is OK, take the battery somewhere "who knows what they are doing" and have it charged and "load tested."

If that is OK, next check your charging system. Buy, beg, borrow or (other) get a multimeter. Run the car long enough to charge the battery after starting, and with all accessories off, check RIGHT AT the battery terminals with your meter. With the engine simulating low/ medium cruise RPM, you should measure somewhere around 13.5 -- 14.5 volts. Anything under this figure (13.5) you need to check out the charging system.

If that seems OK, time to look seriously at the battery cables. Are they clean, do they look deformed, as if chemical action (corrosion) has been going on inside? Clean and tighten all connections.

Then find someone to check "starter draw" This will require the same instrument used to "load test" the battery. It's a great big huge resistor known as a "carbon pile" You may have to pay someone to do this.