Battery light blinking red during charging

During charging, RECHARGE indicator turns red, when the indicator is fashing,

that means battery is almost full and turns OFF when fully charged.

There's some Manual sites here...
https://duckduckgo.com/?t=ffab&q=PWMA1050BT+low+battery+blinking+red&atb=v159-1&ia=web

does laptop work without external power supply,if no then Battery probably not charging Dell computers don't like oem power supplies as often need specific dell charger to suit model laptop so that laptop will recognise it and allow battery to charge

please see the commentary. God bless you

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  The majority of laptops will display a solid green, blue or purple battery light to indicate that the battery is fully charged. Most manufacturers indicate that a laptop is in the process of charging by displaying a solid or blinking green, orange, blue or purple light. If your battery indicator light is green, blue or purple, the battery is probably functional, regardless of whether the light is blinking. If the light is solid orange, the laptop is probably in the process of charging.
  
  

Battery Error Coneventions

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  Many battery manufacturers use rapidly blinking lights to indicate that a battery's charge level is low. In general, a laptop will rapidly blink orange or red when its charge drops below a certain level until the computer is plugged into a power outlet and charged. If your laptop's battery indicator continues to blink rapidly in orange or red or if it remains red even when it is plugged into the charger, it indicates a problem with your battery or the charger.
  
  

Read more: http://www.ehow.com/info_12183593_blinking-battery-light-laptop-mean-charger-not-charging.html#ixzz2fu5qhEWg

Flashing red indicates that the battery is non-functioning (at the end of its ability to hold a charge), although as it is a new battery, this would seem a bit odd.
Did you buy the battery new or 2nd hand, was it a genuine Dell battery? My suspicions are that if this is an aftermarket battery and one which was not compatible with the dell, then there might have been some damage done to the laptop, causing the old battery not to charge. I'm assuming you are using a genuine Dell charger

Looks like you need a new battery. Same thing happened with a DELL XPS, once the new battery was in place, all was fine.

ac/dc convertor board inside laptop faulty.

it means that the battery is bad
replace battery

Seeing as you notice that your battery life is half, this most likely means your battery is no longer able to hold a charge, or a full charge. It could also mean the battery is defective.
If your laptop is still under warranty, the manufacturer may replace it. If not, you'll have to buy a new battery, unless you always keep it plugged in anyways.

Green is charged, Orange is Charging and Red indicates a low charge or a possible weak or defective battery. All modern batteries are controlled by a microprocessor that monitors the health of the cells. Even if the battery is holding a workable charge, it can still be deemed "bad"

If the battery is fairly new you might get a replacement from Dell, if its a year or more old, it could be dying an early but not abnormal death. If more than 1.5 years old, be sure to check the Dell battery recall list as some of these are recalled and you'll get a free battery replacement if its on the list!

-Good luck

What laptop brand and model is it? And where is the LED that blinks? Important details! Some laptops have a power light that blinks red while battery charges, then it turns steady green when battery is full. Some laptops have a red LED that lights whenever there is hard drive, CDrom, or floppy activity (read/write). This all depends on your laptop brand/model and where the LED is (side, near floppy/CD, top near screen, or on battery itself... so provide more details for me, please!