jlwdvm

I have a Optima Red Top (mounted in trunk) in my 69 Firebird with an LS3. I keep it on the battery tender most of the time, but it has been completely drawn down before and I had to bring it back to life with an extra battery, charger, repair setting, etc.
It has to be 5-6 years old, but the car has only been finished and on the road for 3. The starter is wrapped with the best DEI blanket I could get. It will fire right up after I turn the master power switch, but not if it has been driven a while and left to sit. Initially, I thought it was starter heat soak, but I saw no improvement from the blanket. I also checked to make sure my starter wires were tight. When hot, it will turn, but slow...sometimes slow enough that it seems like it isn't going to start. I did some tests:
Volatage at battery after shut down: 12.5 and while running: 13.95. My alternator is putting out 14.2 (at the alternator). Thoughts?

B52bombardier1

Get your freshly recharged battery "load tested" at a good auto parts store - typically, a free test. This is a test of how many amps the battery can discharge. A measurement of a battery's voltage is only one half of the power equation - volts x amps = watts . . . the ability to perform useful work such as spinning a starter. Regardless of a battery's voltage, if it can't deliver the amps . . . it can't do useful work.

If your battery tests good, I'd then suspect a poor connection on the fat battery cable at either the battery end or the starter end.

Rick

jlwdvm

...that was the next thing on my list. Thanks!

jlwdvm

Charged up the battery and took it to Autozone. They confirmed that it is good. I had a 200amp fuse in the positive battery cable (at the battery). Could this be causing the problem?
I fired up the car after removing the fuse and let it heat up for a while. It seemed like the problem was gone. However, not sure if the starter got as hot as it did after driving for a while. I checked my voltage at the battery at idle ad it was 14/5 (the same as what I got at the alternator).

LilJayV10

iTrader: (39)

Start doing voltage drop tests.

TTur1996

Take the starter to a reputable Starter repair shop and have them load test it. The Napa by me does it for example.

LLLosingit

iTrader: (4)

Battery cable size over length of a run also has to be considered. Electric motors pull a lot at the initial hit and improper size can lead to hard starts and premature failure.

jlwdvm

I believe it was 0 gage that I used for the battery cable.

FormulaBoat

iTrader: (1)

What type of starter? Assume it to be mass production or a mini hi-torque model? Most modern compact starters are permanent magnet, and that has alleviated the historic heat soak problems of the larger bodied field wound magnet type.

Best load test is the car itself. Using a digital voltmeter, set the engine so it won't start. Then, have somebody crank the engine for about 5 seconds while reading the voltmeter with test leads on the battery. Voltage should not drop below 10.0v during cranking. If it does, then your battery is shot. 5 years is about max life of a typical lead-acid plate type battery. The Optima's can go further, but not guaranteed. Also, going completely dead does tax them each time. You can also use a handheld battery health meter to measure the internal resistance of the battery. This will tell you the available CCA, and you can simply compare that with the label rating.

If you suspect wiring, you can do the same test with meter leads on the starter motor (alligator clips). You should have near-same results as the battery test. Be sure to check ground cable condition and connection from battery to engine as well. You should not have a fuse in the battery cable to starter, that is typically reserved for the lead coming from the alternator.

There is also the possibility that something is loading the starter or engine more when hot, such as engine condition, transmission, accessory drive devices, etc....rare, but can and does happen.

jlwdvm

Thanks for the input! I do have an Optima red top, but it is probable 7-8 years old. It doesn't have many miles on it, put it has been completely dead a few times to the point where I had to hook it in series with another battery to get it to charge. I have a Harbor Freight charger that has a "Repair" mode...which I have used several times. My starter is a stock LS3 starter that my engine builder (Texas Speed) sent with my motor.

64post

iTrader: (5)

How about a starter draw test in the car? You’ll need to have or have access to an inductive carbon pile type or Midtronic start system tester that will read amperage draw while cranking with the inductor on the power supply cable going to the starter. If the numbers exceed 200 amps while cranking you may be looking at replacing the starter. Don’t over look your ground either, a large awg cable to the block might be in order as well.