It could either have a bad ground to the inner fender, or be full of corrosion. Either of which could cause it to get hot, and if it’s enough to melt the insulation, DO NOT DRIVE THE CAR until you can solve the problem. You may end up watching the car burn.

Too much resistance (or too many amps drawn through a wire) will cause a wire to heat up, and burn the insulation, the cause of the smoking. It sounds as though you aren’t getting a good enough connection to the block, and causing the extra resistance in the neg battery wire. The battery on the other hand…..

Magic smoke (also factory smoke, blue smoke, or the genie) is a humorous name for the caustic smoke produced by severe electrical over-stress of electronic circuits or components, causing overheating and accompanying release of smoke. The smoke typically smells of burning plastic and other chemicals.

If the battery starts smoking during charging, disconnect the charger immediately. The problem might be overcharging, which can only be stopped by disconnecting the charger and letting it cool. You should also check the charger to ensure it is in good condition.

Apple’s $29 iPhone battery replacement deal ended in December, but you can still give your smartphone some extra juice on the cheap—if you make the swap yourself.

In fact, if your phone is being throttled due to battery health, getting a replacement will breathe new life into it. Apple’s fees for new battery installations is pretty reasonable, and certainly much cheaper than buying a new phone. So in this case, it’s definitely worth it.

Sometimes the outdated apps can be the cause of your iPhone 5, iPhone 6 or iPhone 7 battery draining fast suddenly. Therefore, you should turn this feature off to extend battery life on your iPhone or iPad. To turn it off go to Settings> General> Background App Refresh> Toggle ‘Background App Refresh’ to off position.

According to Apple, the iPhone’s battery is designed to retain up to 80 percent of its original capacity at 500 complete charge cycles, so if the full charge capacity is less than 80 percent of the design capacity, of the recharge cycles exceed 500, then your battery is considered worn.