3. Acid on Soldered Joints. Amateurs sometimes attempt to make connections by the use of a soldering iron and solder. Solder is readily dissolved by acid, not only spoiling the joint, but endangering the plates if any gets into the cells. Solder must never be used on a battery except for sweating the cables into the cable lugs, and the joint even here must be well protected by rubber tape.
4. Defective Posts. Posts withdrawn from the post mould before they are cool enough may develop cracks. Bubbles sometimes occur in the posts. Either trouble may reduce the current carrying capacity or mechanical strength of the post and result in a broken or burned-out spot.
5. Plates Improperly Burned. As previously explained, this is not likely to cause immediate trouble, but by imposing extra work on the balance of the plates, causes them to wear out quickly.
Battery Discharged
1. Due to excessive use of starting motor and lamps.
2. Failure of generator.
3. Defective switches, which by being grounded, or failing to open allow battery to discharge.
4. Defective cutout, allowing battery to discharge into generator.
5. Addition of accessories, or use of too large lamps.
6. Defective wiring, causing grounds or short-circuits.