When Cadmium Readings Should Be Made
1. When the battery voltage drops to 1.7 per cell on discharge before the battery has delivered its rated ampere-hour capacity, at the 5-hour rate when a discharge test is made.
2. When a battery on charge will not “come up,” that is, if its voltage will not come up to 2.5-2.7 per cell on charge, and its specific gravity will not come up to 1.280-1.300.
3. Whenever you charge a battery, at the end of the charge, when the voltage and specific gravity no longer rise, make Cadmium tests to be sure that both positives and negatives are fully charged.
4. When you put in a new group, charge the battery fully and make Cadmium tests to be sure that both the new and old groups are fully charged.
5. When a 20-minute high rate discharge test is made. See page 267.
That Cadmium Readings should be taken only while a battery is in action; that is, while it is on discharge, or while it is on charge.
Cadmium Readings taken on a battery which is on open circuit are not reliable.
When you are not using the Cadmium, it should be put in a vessel of water and kept there. Never let the Cadmium become dry, as it will then give unreliable readings.