red light on Magsafe power cord

Red just means that it needs to charge. Whenever you plug in your charger, it will flash green for a second, and then if the battery needs charging it will turn amber to tell you that the battery is not full yet. Nothing bad - that's what my MagSafe does at least 🙂

Does it stay red? Does it flash red? Does it ever start charging "turn amber".
You might try to reset the SMC/PMU

Mort

it would take about 3 hours to fully charge the macbook battery. (having the macbook turned off)

then the red light on the magsafe would turn to green indicating the battery is full charge