OK, I've got an 01 Blazer LS 4x4 4.3 auto. She's been sitting for almost a year due to a brake line going out and a lack of any need for it. An ex of mine got swindled on a 96 Jimmy with a blown head gasket but new inspection sticker!
So I've offered this 01 to her to try and make the best of her ****uation in hopes 1 driver can be made of the 2. My 01 is newer has less rust and doesn't need a head gasket so it seems the obvious choice of the 2. I'm not masochistic enough to swap engines cause the 96 is a prettier color.

Anyway, on to the problem at hand. The 01 was running fine 8 months ago, but I pulled the battery for another vehicle. I had done a top post conversion with those cheapo napa adapters because I had a new battery from a 94 ranger that was scrapped. So without a battery yet I tried starting it with an optima red top from an 83 capri I had parked in front of it. No dice, lights came on but flickered and I got a clicking noise while turning it over. Like a starter solenoid'ish sound. Figured maybe it was something with the top post conversion, and gave up there as she was bringing over the brand new side terminal battery from her jimmy the next day.

So I picked up a pair of new side terminal bolts, removed the rubber covers and wire brushed the wire terminals before putting it back together and installing the new battery. Tried turning it over and got the same result.
I hooked up my ole' schumacher battery charger and it was reading around 65%. I figured it was low from trying to start the 96 and thought nothing of it.
I left it on 10 amp fast charge and went out to run errands for a few hours. I get back and she's basically reading the same. This seemed odd. I played around with the alligator clips to no avail, then decided to turn off the charger and choose a different ground point. I hooked the ground clip to the throttle cable bracket, turned the charger back on and the meter pegged. This leads me to believe perhaps the battery ground is weak. I didn't dare try to start it this way as the battery charger cables are basically lamp chord gauge.

So I have some leftover 4 gauge OFC and some 0-rings laying around. I was thinking I should add another and/or replace a ground to the battery terminal?
Or am I likely having another issue here? If I do make a new ground where should I put it? Can I go from the battery terminal to the big bolt on the front of the alternator bracket? Seems the closest and largest bolt going into the block to me. Would I be better off going to the frame or chassis?
'

 

What do your current ground wires look like? Have you detached them to do an inspection?

 

They look fine at the terminal, I haven't traced them to where they are grounded other than the little guy that goes to the rad support. So no, haven't detatched em. Between the age of the vehicle and being in Maine where we toss down road salt I figure if one's going to the frame it could be rusted/corroded. The smaller gauge one going to the rad support seems fine. Everything on it seems to be getting enough juice to function aside from the starter. So I'm trying to figure out the best place to add a ground that doesn't involve getting under the truck with a grinder. I'd rather just leave what's there in place since I'm guessing it's not harming anything.....It's just inadequate. Looking for an easy to get to spot within 3 feet of the battery that can be cleaned with a hand wire brush and be secured using existing hardware that will provide a solid ground. Alt bracket bolt seems perfect but makes me nervous grounding to a bracket holding THE power source.

 

Oh yeah, another possibility is it could be the ignition switch I've been told? Does anyone know if these are interchangeable from a 96 Jimmy to an 01 Blazer?

 

Rereading your original post (and with some caffeine in my bloodstream), these thoughts came to my mind:

1. Are not battery grounds (the main big one) normally to the block of the engine? That would ensure a good ground for the starter also.
2. What happened when you tried to charge the battery with the cables of the charger connected directly to the battery terminals? If the batteries could be charged when hooked up directly, that could eliminate them as the culprit.
3. Your symptoms do sound like the systems are getting enough voltage but there is too much resistance in the wiring (or internal to the battery) to allow much current to flow.

 

1. In most cases I would think so. Hence why I want to add a new ground with newer higher quality cables and terminals from block to battery.

2. The optima had full charge. It would not start the truck, but when removed and re-installed in the mercury capri it was able to start that. Mind you the capri has an aggressive cam, a 4bbl atop a single plane and an MSD 6al. Certainly harder to turn over.
The napa side terminal battery is only a few months old. It would barely charge while installed with the charger hooked to it. While still installed I removed the ground clip of the charger from the neg terminal of the battery and clipped it to the throttle cable bracket mounted atop the intake manifold. This charged the battery. Hence my belief that the ground is the culprit. With the battery charged and the charger removed it would NOT turn over. I'm pretty positive[bad pun] that the battery is not at fault.


3.I'm pretty sure I've got a resistance issue in the ground wires, or possibly the power wire. I made a new ground and hooked it to the alt bracket a few hours ago, but wasn't able to hook it to the battery with the existing terminal. Couldn't get the sidepost bolt to thread into the battery as the extra 0-ring took up too much space for the bolt to grab the threads in the battery.

I have a 4 way top post distribution block from a car audio setup laying around. Since the factory terminal has 3 grounds and I'm adding 1 this should work perfect if I get one of those adapters that thread into sidepost batteries and give them a stud post terminal. Gonna pick one up tomorrow morning and hopefully it fixes it.

 

Solved! Adding the 4th ground to the alt bracket and no more power loss. Turns over now, but won't start. Hoping it's bad gas from sitting. Going to try the fuel filter. It has spark and cranks so that's half the battle, thanks!