Engine ticking - low MPG - HV Bat not getting a full charge

I picked up a cheap Gen 2 as a backup. When the Amazon driver folded my two left doors forward on my main car, I pressed this one into service early.
I've replaced the rear struts, put my good tires on it and had to replace the windshield. It works, but there is a ticking sound. Sounds like valve lash ticking, but it comes and goes. Mostly comes, but sometimes it stops while the engine is running. Is there anything NOT valve related that would make that sound? The fact that it disappears at times raises that question.
Second issue is that the engine likes to run most of the time. I'm used to "feathering" the throttle to get it to run off the HV Battery, but this one doesn't like that mode much and mostly just runs. Mostly... Oh, and it acts like the "the transmission is slipping". If I accelerate strongly, when I hit a certain speed, the engine goes into high RPM and I let off the gas to reduce the RPM. Then it will still accelerate up to 70 without overrevving the engine. But it takes a bit of finesse.
Third, the HV battery doesn't get a full charge most of the time. I've switched HV batteries with the same outcome. Yes, they're both old, but I've reconditioned many of them and have had good results always...except this time. I don't think it's the battery(s). I have had the battery take the almost full charge during a mostly downhill time which tells me that the battery will take the charge if given the opportunity. Something up with some computer related something, I'm guessing.
And finally the only codes I'm getting are:
P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0420 Catalyst System Efficiency Below Threshold (Bank 1)

 

She's got 282205 on her.
Code reader is a Foxwell NT716 Four System Scanner
And I'm just saying that it doesn't look like it is usually charging up over half. But it CAN given the right (downhill) stretch.

 

And, one of those batteries just came out of my other car that was working right, /so I feel confident it is NOT the battery..

 

I figured I'd ask here first. Those don't look to me like they could cause those issues, but hey, I'm no expert. That's why I come here with my problems.