Screen goes blank when on battery power

I'd say that you have exhausted your options. You can try to isolate the power on problem by removing your your memory modules, hard disk drive and see if it at least stays powered on. Here is a link from Dell for your laptop's manual:
ftp://ftp.dell.com/Manuals/all-products/esuprt_laptop/esuprt_inspiron_laptop/inspiron-1521_Owner%27s%20Manual_en-us.pdf

May be your Power cable is faulty.

Tip

1- just use another cable and check .
2- Use another power socket, may be earthing will be issue here

Hello.

The most common reasons for power issues are the battery, power jack and power adapter/cord.

If you move/wiggle the power adapter at the point where it connects to the laptop, and the power goes off and on, the power jack is the problem.

The power jack is inside the laptop and either needs soldering or replacement. If a power jack problem, it should be addressed by someone knowledgeable.

But, as you described, the power adapter is probably faulty and needs replacement.

Hope this helps.

i want to see my screen display normal ..

you need to by a new battery

How about the battery backup - computer goes to stand by mode automatically if battery fails in power .

check whether computer goes in standby on battery only or when pluged in charger also

I have a Dell Inspiron 1525 and had the same exact problem. I finally called Dell and they sent a tech out. They replaced my power cord and all the software. The reason for this is because Dell Inspirons has a default in the AC cords. Sounds like the AC power cord is the problem. You could find someone who has this cord and test your Inspiron with it or try calling Dell! It worked for me.

I see possible failure as the following:

1. The power control strip on the Palmrest Assembly (The actual button under the hinge cover)
2. The motherboard, even though the system partially functions under the DMD button, that is a very limited function of the system

plz concert with hardware vender coz it is not possible for u. if u can see perfect boot screen than u must re installing ur oprating system.that mean ur hardware is perfectly working. enjoy good luck

I believe I have found the problem with the 1525 that I am currently working on which has the same problem that you describe. Ultimately I think it's a problem with the inverter in the LCD. When the laptop is powered by battery the brightness is lower than full. When I plug in the power adapter the brightness goes to "full" and I hear a faint sizzle and the LCD's backlight goes off. Same as if you hold the Fn key and press the up arrow to brighten it, it will do the same thing when you reach near the full brightness. So for now I have fixed this problem by going in the Power Options and clicked on Adjust the display brightness on the left. Slide the slider to the left on the "plugged in" part and now when you plug it in it shouldn't make it go blank. I do want to note that I hear a faint buzz coming from the LCD when I plug it in. That must mean the inverter is faulty. WAY TO GO DELL!!!!!!