Info on Dell laptop charging issues and whats really going on.

I have a Dell Inspirion 13 7347 laptop with an Intel I3 processor that runs at 1.7ghz that is a old work computer.
About 3 years ago, I noticed that the 35Watt adapter that is recognized by the bios (I have latest version) didn't seem to be charging the battery from time to time. So I went out and bought a 90Watt Dell adapter but it isn't recognized by the Bios. It has plenty of power and seemed to be working.

Over time, I noticed that it didn't seem to always start charging the battery immediately when plugged in although the display went from dim to bright. It seemed to be randomly charging the battery. I checked Dell forums and saw that this seemed to be a common problem across all Dell laptops. Also the internal power jack became loose due to the fragile plastic tab with screw that holds it down. Thus, I ordered off of ebay a new replacement power jack and replaced the old one. Now it doesn't wiggle around when the power jack is inserted, but the intermittent problem was still there.

Observations and testing over time:
1). One thing I noticed when the power jack is inserted is,,
a. the screen getting brighter of course
b. the task manager shows the processor speed dropping from the max of around 1.7ghz down to half or 0.8ghz.
This is another common complaint that one isn't getting full speed. Although speed-step in the bios is activated, one would think that on battery that processor speed would slow down to make the battery charge last longer, or that due to the laptop getting hot that it would slow down to cool down, but not that it would slow down when it should be running at max with all the power it needs from the power adapter being plugged in vs. battery.

c. so based on plugging in the battery it would randomly run at max cpu speed and/or charge the battery. When not charging while plugged in, I noticed that the processor ran at 0.8ghz, the battery percentage never increased and that the system tray battery icons bar never moved or that the "time to full charge" never changed.

d. making a guess, I thought that it may take "three" attempts to get things working right. That is - and the solution - is to plug the power adapter into the laptops power jack three times by: 1) plug it in see screen go bright, then remove and see it go dim, 2), repeat step 1 two more times and then leave it plugged in.

e. After three power plug insertions per step (d), the screen will be bright, the system tray battery icon bar will start to move for only 5-6 times and then this bar stops moving (I guess this how it works), the task manager shows the processor holding steady at max cpu speed of 1.7ghz, and then the battery percentage and "time to full charge" appears.

Thus, the laptop hardware or bios programming must have some type of counter that makes the laptop act like this as if a intermittent problem.

My battery life settings has a checkbox to extend battery life. Currently not checked. However, if checked it doesn't give an option to set a percentage.

My power options for the processor are:
min processor state, 5% on battery 100% plugged in
system cooling policy is active for battery and plugged in
max processor state is 100% for both battery and plugged in.

all other hardware set to max performance on battery and plugged in.
Display is the only one that turns off after xxx minutes on battery vs. plugged in.

The bios is basically very minimal/primitive. It doesn't give an option to set battery life. WIndows 10 pro settings for battery life as described above is all I have for this Dell Inspirion 13 7347 laptop

1. The battery is many years old and probably has only a small capacity left. Is it 10 years old or something like that ?

" the task manager shows the processor speed dropping from the max of around 1.7gbh down to half or 0.8ghz
This is another common complaint that one isn't getting full speed."

People do not understand the purpose of speed stepping which is to save power from the point of view of battery power consumption and to minimise the heat generated whilst maintaining a decent performance, that 0.8 GHz steps up only when required, it is not random.
Even when plugged in to run at max turbo continuously would cause long term heat damage as laptop cooling is pretty minimal.

"should be running at max with all the power it needs from the power adapter being plugged in vs. battery."

That is not the case, running at max (Power Mode 3) also increases the heat generated, not good in a laptop.
You should have a slider control for Power Mode, click on the Battery Icon bottom right.

That should give you 3 settings the first 1 for "best battery life", and 2 for "better performance" will give max no of steppings of the CPU, and 3 last "best performance" will step from base frequency to max turbo.

"My power options for the processor are:
min processor state, 5% on battery 100% plugged in*
system cooling policy is active for battery and plugged in
max processor state is 100% for both battery and plugged in."

*That will not do what you think it does. it is just the base frequency as in Power Mode 3 it will when required go up from base to max turbo.

What is the exact CPU ?
The quoted speed is usually the base frequency, specs showing max turbo and number of steppings, thence the min frequency.