Batteries are everywhere; indeed they are and your aircraft is fitted with them. Fortunately, they rarely go wrong.
I had the aircraft battery (NiCad) blow up on me over northern Kenya at night (Aden to Nairobi) in one of Mrs Windsor's Argosys. It started off with a smell. F/E went downstairs (the battery was in a cupboard on the left of the forward fuselage INSIDE the pressure hull). Naturally, he took the asbestos gloves with him to investigate. He came back upstairs and told me that he had found the battery "rather hot" and had disconnected both terminals and so we should have no further problems until after landing.
About 20 minutes later there was a bit of a "whump" as the battery blew. Luckily, everything was contained within the cupboard.
We then had to do an emergency descent (not very far in an Argosy) and then get rid of the fumes.
It transpired that NiCads can indeed start to overheat so a thermal strip was introduced between the first couple of cells and that was supposed to melt. Sadly, it did not and so the temperature kept increasing and eventually a catalytic reaction took over.
The funny part was that a bunch of the passengers downstairs were on their way to a gospel meeting in Nairobi. From the flightdeck we could clearly hear renditions such as "Land of Hope and Glory" and "Abide With Me".
I can also remember one of Fred Laker's DC-10s doing an unseemly dive into Winnipeg on the way from LGW to LAX with serious electrical problems which proved to be the battery.
Just like car owners, we take our batteries for granted.