I did this by accident at the secondary airport on Bangkok when we were taking a domestic flight. The result was the very camp airline staff member running around the security queue area screaming my name. When he found me, they explained that it has been found at xray and gave me the opportunity to remove it from my checked luggage and take it with me in my hand luggage (it was below the 10 ah (10,000,000uah) limit ). I thought it was very good service and highly amusing. I wouldn’t expect that to happen at most airports, probably they would just remove the battery from your bag and you would loose it or maybe even the entire bag.