dell inspiron 5040 plugged in not charging?

How old is the battery? Was it frequently recharged? Even with an almost full charge.
Was it left totaly drained for any time?

This is NOT specific to your laptop. It apply to ALL Li-ion batteries no mather what they are used for.

If it works on the charger but you can't get the battery charged, it mean that your charger is OK but the battery is dead or almost dead and need to be replaced.

The battery is good for about 1000 to 10000 charge-drain cycles. Recharging when at 95..99% charge count as one full cycle. Only recharge when the remaining charge is less than 20%.

If ANY Li-ion battery is left drained (charge at 0%) for a few days, it dies.
When the charge drops under 10%, recharge as soon as possible. If the charge drop under 5%, STOP using it NOW!
If you can't recharge promptly, DON'T use it in any way. It may beter to remove it from the computer to prevent it from totaly draining.

If left unused for a long time, it will progressively loose it's charge. In this case, the charge can drop to zero. When in storage or otherwise unused, you should recharge it about every 6 months.

Don't leave the batery on the charger when fully charged: This will damage the battery, shorten it's life and may prevent it from getting a full charge.

Electro
September 2014