6. Bench Charge Method. — Once every month, add distilled water to replace evaporation. Then give battery a bench charge. See page 198. Before putting battery into service repeat this process and just before putting the battery into service, make the high rate discharge test on it. See page 266.
7. Trickle Charge Method. — This consists of charging the batteries in storage continuously at a very low rate, which is so low that no gassing occurs, and still gives enough charge to maintain the batteries in good condition. In many cases the "Trickle" Charge method will be found more convenient than the bench charge method, and it has the advantage of keeping the batteries in condition for putting into service on short notice. It should, however, be used only where direct current lighting circuits are available.
In the "Trickle" method, the batteries are first given a complete bench charge, and are then connected in series across a charging circuit with one or several incandescent lamps in series with the batteries to limit the current. In Fig. 151, an example of connections for a "Trickle" charge is given. The charging current for different sized batteries varies from 0.05 to 0.15 ampere. The following table gives the lamps required to give the desired current on 110 volt circuit.
In each case, the lamps are connected in series with the batteries. The "2-25 watt, (lamps), in parallel" listed in the table are to be connected in parallel with each other and then in series with the batteries. The same is true of the "3-25 watt (lamps), in series" listed in the table.
Series on 115 Volt Line
| Amp. Hours Capacity 5 Amp. Rate | Amperes Approximate | No. of Cells in Series on Line 115-Volt | No. 115 Volt Lamps Required 115-Volt |
|---|---|---|---|
| 50 or less | 0.05 | 3 | 5-15 watt, in series |
| 50 or less | 0.05 | 30 | 2-15 watt, in series |
| 50 or less | 0.05 | 45 | 1-15 watt, in series |
| 50-100 | 0.10 | 3 | 3-25 watt, in series |
| 50-100 | 0.10 | 3 | 1-25 watt, in series |
| 50-100 | 0.10 | 45 | 2-25 watt, in parallel |
| 100 or over | 0.15 | 3 | 2-25 watt, in series |
| 100 or over | 0.15 | 30 | 1-25 watt, in series |
| 100 or over | 0.15 | 45 | 3-25 watt, in parallel |
Every two months interrupt the trickle charge long enough to add water to bring the electrolyte up to the proper level. When this has been done, continue the trickle charge.
Before putting the batteries into service, see that the electrolyte is up to the correct level, and that the specific gravity of the electrolyte is 1.280-1.300. If necessary, give a short charge on the charging bench to bring the specific gravity up to the correct value.
Dry Storage
1. Give the battery a complete charge. Pour out the electrolyte, and separate the groups. If the negatives have bulged active material, press them in the plate press. In batteries such as the Prest-OLite in which it is difficult to remove the plates from the cover, the groups need not be separated unless the negatives have badly bulged active material. It may not be necessary to separate the groups even then, provided that the positives are not buckled to any noticeable extent. If only a very slight amount of buckling exists, the entire element may be pressed by putting thin boards between the plates in place of the separators.