Battery appears charged, but computer will only run when plugged in

If I understand you correctly, you are saying the computer will run with the AC adapter plugged in, but will not start on battery power even though the battery appears to be charged. Most likely the battery is defective. If it won't run on battery power with a known good battery, then there is a problem in the power control circuit on the main logic board inside the computer.

Batteries have electronics data that software has to get to properly charge it. Newer lithium batteries maybe different. But apparently, you have a work around for a lengthy use of the new battery.

You are looking at having to replace the motherboard here, as the charging circuit appears to not be working. I assume the computer works as long as it's plugged in, so the DC-in jack must be OK

Check for a DC connector problem:

Symptoms of a broken power jack
1. If you wiggle the power cord or the AC Adapter connector on the back of the laptop, the power LED and battery charge LED start to flicker.
2. Battery will not charge in the laptop.
3. Laptop runs fine off a charged battery.
4. With the AC Adapter connected the laptop appears to be dead.
No power LED or battery charge LED activity.
5. Laptop randomly powers off without any warning.

If your laptop is out of warranty, then you can fix the problem by re-soldering DC-IN jack on the system board. If it

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

it means your battery is damaged. avoid using battery while using charger in your house. remove battery to be safe. battery is for outside or for travel only.

try running with battery out it should still work as long as it is pluged to a/c

Most Dell batteries have an LED indicator that allows users to see how much run time and how much overall battery life are available at the touch of a button.
To check battery charge, press the button and the number of lights that appear will tell you charge status. If all lights appear, you have a fully charged battery. Each light that appears accounts for approximately 20% charge.
To check the battery health, press and hold the status button on the battery charge gauge for at least 3 seconds. If no lights appear, the battery is in good condition and approximately more than 80 percent of its original charge capacity remains. Each light represents incremental degradation. If five lights appear, approximately less than 60 percent of the charge capacity remains, and you should consider replacing the battery
if the ac adapter will power the laptop without the battery installed its fine. if the cord is fine and your battery is fine its a mother board issue and it will most likely have to be replaced

If the battery is not charging, then the charging circuit of the motherboard is bad.

Page 3-22 lists the spare part number for the motherboard. (4 versions depending on options)

Chapter 5 covers disassembly and reassembly

http://www.hp.com/ctg/Manual/c00212209.pdf

1. Toggle the Hold switch. To do this, slide the switch to Hold (an orange bar appears) and then slide it back (orange bar is hidden).
2. Reset the iPod by holding down the Menu and Center buttons for 10 seconds.
   
   If the Apple logo appears on the display, connect the iPod to a computer and verify that it appears in iTunes and can play music. If the iPod appears in iTunes and can play music, no further troubleshooting is needed.
   
   If the Apple logo does not appear or the iPod is not seen in iTunes, connect the iPod to a power source by either plugging it into an Apple iPod USB Power Adapter or directly into a computer's USB port.
   
   
3. Let the iPod charge for at least 20 minutes. Note: If the iPod is connected to a computer, make sure the computer is not set to sleep, standby, or hibernate.
4. After the iPod has charged for at least 20 minutes and while it is still connected to the power source, toggle the Hold switch again as in step 1.
5. Try resetting the iPod by holding down the Menu and Center buttons for 10 seconds.
   
   If the Apple logo appears on the display, connect the iPod to a computer and verify that it appears in iTunes and can play music. If the iPod appears in iTunes and can play music, no further troubleshooting is needed.
   
   If the Apple logo does not appear or the iPod is not seen in iTunes, the iPod should be serviced.

Your laptop needs a new battery. Buy a new one and have it replaced by a service technician for free.