New battery starter still cranks slow

[Steven Petersen]

I just installed a new Delco battery a few days ago. The old battery was a 6 year old Sears that the previous owner installed. My cranking was slow plus I killed it about a month ago by leaving the key on overnight during my valve seal replacement project. With this new battery, I’m only seeing a very slight improvement in cranking speed. Cables are OEM and connections are clean. I’ve also checked voltage drop from battery negative to frame and engine ground. Both within spec .2V. I assume it’s the original starter so I may just replace it. Any other things to check first? Also, battery voltage is 12.32. Seems a bit low, aren’t they usually closer to 12.5?

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[PlayingWithTBI]

Also, battery voltage is 12.32. Seems a bit low, aren’t they usually closer to 12.5?

Did you throw a trickle charge overnight into it 1st?

 

[Steven Petersen]

Did you throw a trickle charge overnight into it 1st?

Supposedly the shop I bought it from did, but who knows for sure.

 

[slovcan]

Classic old worn starter symptom. If you open it up you'll get a cup of carbon dust out of it. You'll likely also find at least one brush at or below minimum spec. I don't know if they have a bearing or bushing for the armature shaft. Bushings wear.

Charge the battery overnight like PlayingWithTBI mentioned.

Cheers,
Glenn

 

[90 Silverado]

My AutoZone recon starter just gave out last week after 11 years, Bosch Battery went down a cell at the same time, got only 3 years out of it, last one lasted 6 .

Back in the day, I worked at an AC Delco / Motorcraft warehouse in Arizona, that supplied parts to dealerships. We sold Delco batteries like yours like butter , most only lasted 3 - 6 months on average on brand new cars.

Doug in P.R.

 

[Schurkey]

I’ve also checked voltage drop from battery negative to frame and engine ground. Both within spec .2V.

What's the VD on the positive side--Battery + to starter solenoid post?

You are doing the VD testing with the starter CRANKING, right?

Also, battery voltage is 12.32. Seems a bit low, aren’t they usually closer to 12.5?

Fully-charged battery should be 12.6--12.7, AFTER the surface charge has dissipated.

A battery at 12.3 is very discharged.

 

[Steven Petersen]

What's the VD on the positive side--Battery + to starter solenoid post?

You are doing the VD testing with the starter CRANKING, right?


Fully-charged battery should be 12.6--12.7, AFTER the surface charge has dissipated.

A battery at 12.3 is very discharged.

Yes, I did the voltage drop tests with the crank and inj fuses pulled and cranking the engine, as per the service manual. I have not done the positive cable tests yet. I’ll need an extra person for those.

I just went out and rechecked voltage on the battery. Also on my 14 Sierra and 18 Yukon for comparison. 88 12.4, Sierra 12.4, Yukon 12.23. I then hooked up my scanner and it also showed 12.4 on the 88.

 

[Schurkey]

I guess you need to charge a bunch of batteries.

You shouldn't need a second person to do a VD test, but you may need to extend the positive and/or negative test lead so they're long enough to reach the battery and the stud on the starter solenoid while still leaving you able to see the meter when cranking.

 

[Steven Petersen]

I guess you need to charge a bunch of batteries.

You shouldn't need a second person to do a VD test, but you may need to extend the positive and/or negative test lead so they're long enough to reach the battery and the stud on the starter solenoid while still leaving you able to see the meter when cranking.

On the batteries being low. I used to have a really good battery shop that I know for sure charged all my batteries before I purchased. I really never knew the reason or thought much of it. Is this something that has to always be done? Why does the alternator not bring them up to the proper voltage? Please educate me on this.

 

[PlayingWithTBI]

Is this something that has to always be done? Why does the alternator not bring them up to the proper voltage?

The alternator and voltage regulator maintains the battery's charge. It needs to be fully charged to begin with. That's why you want to occasionally throw a trickle charge in it. I'll throw my 30 year old 6Amp charger on it every Month or so. It'll put out ~2 - 3 Amps until it's done.