redvetracr

Just curious if anyone can help with an odd set of circumstances?? Car battery tests good on both a Snap-On load tester and an (expensive looking) Med-Tronic hand held tester BUT will not start the car it is in. I swapped that 7-1/2 year old original battery with an older Delco and it starts (yea I know 7-1/2 years is a long time, but I am still curious), I bought a new NAPA "Legend 75" and it starts and starts and starts...question is how does a battery "test" good, but will not start the car??????
THANKS in advance!! ...redvetracr

Boofers

The tester should be able to simulate a starter, meaning it should draw from the battery a couple hundred amps during the test, which is what the starter draws when turning over the engine. If the tester only draws like 20 amps it is not a real test.

Durango_Boy

A battery can have 12+V and not be strong enough to start a car. Sometimes they diminish their ablilities. Like having a one operational cell in the battery holding a charge or 12V but because only one of the eight cells is working, you couldn't start a lawn mower if you tried. The battery has to be tested with a load, and should tell you what amperage is being drawn. Save the trouble though, and get a new battery. DON'T buy a battery from Autozone. Oreilly has good cheap batteries, but your best bet is an Optima, and a tender. You'll have no battery issues for several trouble free years.

redvetracr

After starting the car maybe 10 times the car wouldn`t start...so much for a bad battery.....I finally got it started and took it straight to a mechanic....I am a parts replacer...and the first to admit it!!
...redvetracr

Kalway

What's wrong with Duralast gold batteries? 3 year free replacement

Boofers

Personally I prefer the term 'parts jockey'

Thats a play on 'disc jockey' for all you kids out there, the short form of which is 'DJ'

Durango_Boy

I went through three of them in a month before I found one that was good. It may not be a Duralast thing...I think Autozone just doesn't cycle their batteries, and they sit too long and go bad like ours do on out garage floors.

cardo0

Yea it sounds like the old batt still had some amps in it but maybe not as many as the new batt. That would explain the "good" tester readings. And if lead acid wet cells are regirrously maintained they can last much longer than expected. Heat (>90*) is a killer and look where most cars batts are located - in hot eng compt. But at least the vette has a much cooler batt location.

Just a thought redvetracr, a hi compression eng will be a much greater load on the stater/batt sys. Are u strill running the stock starter? Try a mini-starter with gear reduction? Just my 2 pennys.
cardo0

redvetracr

I had a long talk with the owner of the local NAPA store....he tells me there are quite a few levels of quality, the maunfacturers just ask what do you want to pay and they build the parts (batteries, shocks, starters, etc.) accordingly......If he wants to buy enough batteries or shocks or what ever they will even put his name on them.....considering there are only three battery manufacturers in this country I now understand how some batteries are so much cheaper than others....quality....and waranty....he also tells me the number of "bad" parts replaced is so small it is insignificant.
...redvetracr


PS: The car in question is NOT my racer.....My racer has had a reverse drive gear drive Quartermaster starter and 5.5" clutch for some time now.

Durango_Boy

My step Dad used to know a guy who's truck battery lasted him almost ten years. He lived on a hill, and while he didn't drive often, he would start his truck, a manual, by rolling it down the hill and push starting it every time. Obviously running and arrend he couldn't always do that, but by not using the starter motor that many of the times he extended his battery life considerably. I personally think that's too much work for such a small gain...it's not like car batteries are horrible to afford...

redvetracr

I have a `94 Ford F-350 dually crewcab w/turbo diesel with two batteries, the factory Motorcraft batteries lasted 10 years plus...so thats easy to believe, my truck (now) has 83K miles.....
...redvetracr

Durango_Boy

Two batteries makes a huge difference. You're spreading the starting load over two batteries. Starting is what kills the battery and causes that white crap. Using twins is like using a battery with almost 2000 cranking amps. I do twins in my trucks, and my Vette is gonna get the same treatment, twin Optimas.