Popular Science MontJily 



781 



Lamp Resistance for Charging 

 Storage Batteries 



A LAMP bank resistance for reduc- 

 ing current in charging storage 

 batteries, while wasteful of energy, is 

 cheap in construction and is often use- 

 ful in power houses or in those few 

 places were electric current is abnor- 

 mally cheap. The lamps are inserted in 

 holes bored in a soft pine plank, mak- 

 ing contact on the lower side with strips 

 of copper or brass that are fastened by 

 tacks. Contact with the other lamp ter- 

 minals — the threaded bushings — is made 

 by winding clean copper wire in a zig- 

 zag fashion between the lamps' bases, as 

 indicated in the diagram. The wire 

 should be wound about each lamp base 

 several times to secure adequate contact, 

 and soldered, if possible. A fuse block 

 should be provided and the connections 

 made as shown. 



Old lamps are best, as their resistance 

 is lower than new ones. If the polarity 

 of the current is not known it can be 

 found by placing one wire of the circuit 

 in a tumblerful of water with a wire 

 from the lamp bank opposite. Only a 

 couple of lamps should be used in this 

 test. By noting the bubbles that arise 

 from the two wires, the polarity can be 

 determined by marking the wire from 

 which most bubbles rise. This is the 

 negative side. Storage batteries will be 

 ruined if the connections are not correct- 

 ly made. 



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Method of recharging dry batteries by 

 immersing them in salt water 



A simply arranged lamp bank for reducing 

 voltage when charging storage batteries 



Recharging Worn-out Dry Batteries 



DRY batteries are made of dampened 

 carbon cobalt. That all batteries 

 have not the same life is due to the fact 

 that they are dry from use, or leakage 

 from evaporation through the top. 

 Cheap batteries do not contain the 

 quality of carbon found in high-grade 

 batteries ; hence it is useless to recharge 

 cheap ones. A good high-grade battery 

 will recharge three times before it is 

 worthless. 



Take six worn out batteries, drill four 

 holes in the top of each through the tar 

 covering (a red hot nail or a small drill 

 will do), so that the black carbon can 

 be seen. Fill a pail with water, so that 

 it will be about one inch higher than the 

 tops of the batteries. Dissolve three 

 good handfuls of common table salt in 

 the water. Do not use sal-ammoniac. 

 Place the batteries in the pail in a stand- 

 ing position. Leave them for eight 

 hours, stirring the salt water about twice 

 during that time. 



After removing the batteries, stand 

 them upside down to let what water will 

 run out (about two hours). Then seal 

 them with a hot soldering iron ; connect 

 them, and they are ready for use. This 

 can be done three times. — T. F. BusCH. 



