Battery Drain on 2000 Suburban

[khansen46]

We have a 2000 Suburban 1500 4x4 that my wife inherited from her mother. We've been fixing all the little things here and there, but we're having an issue with the battery draining. If it sits for more than a day the battery goes dead. We've replaced the battery a couple of times in the last 2-3 years. I've used a multimeter and pulled fuses one at a time, but don't see a constant draw. I've disconnected the VCR and power inverter. It has an aftermarket radio, and I've pulled that fuse. Still no luck. One strange thing I've noticed is that it won't run with the battery charger connected. It will start, but dies as soon as I release the key. As soon as I disconnect the charger after charging it, it starts fine. I'm stumped. Is it possible there is an issue with the alternator and/or voltage regulator? Is there something else I may have missed?

[Charles_Colfax]

I'd pull the alternator and have it tested.

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[khansen46]

An update on this. The issue still exists. Alternator tested fine at AutoZone and we've gone through a few batteries, so neither is the issue. It's not a constant or predictable drain. I've let it sit 2-3 weeks and it started fine. Last week I drove it around for a few hours after the battery was fully charged, and the next morning it was dead. 

One odd thing I've noticed. When charging or jumping the battery, it will start and then die if the external power source is connected. I have to charge the battery, disconnect the charger, and then start it. I've never seen that before. I've put a volt meter inline on the positive side and have never seen any abnormal draw. I've randomly pulled fuses but haven't seen any significant or unexpected change in draw. I've pulled fuses and let it sit overnight and still came out to a dead battery. 

I've been to a couple of shops and they can't figure it out. 

This vehicle has sentimental value to my wife so we will never get rid of it. If necessary, I'll start replacing electronics one at a time, and the wiring harness if it comes down to it. But I sure don't want to go down that road if I don't have to. 

[khansen46]

FINAL UPDATE: I bought an Optima Yellow top battery. At over $300, I'll admit it was reluctantly. I started it to make sure all connections were good and shut it off. The Suburban sat untouched for 9 days and it fired right up. I let it run a while to warm up and turned it off. 

It has now sat untouched for over two weeks. This morning it's 42 degrees in SE Texas. The Suburban fired right up with no hesitation. 

I've installed multiple new batteries in it the last several years since we've had this parasitic drain, multiple brands. I have read about the electronics drain on batteries from this model. I don't know if the quality of batteries has declined, or if the Yellow Top is just able to mask or compensate for the issue, but it is fixed enough for me. We'll see how the Optima does over time, but I'm happy. 

[KARNUT]

I’ve had two vehicles of different brands drain batteries after two weeks not being driven. Three when the battery was new. The only common theme was aftermarket alarms.