When the fire alarm telegraph was first invented, it was found that in order to make it absolutely reliable, it was necessary to have the circuits under constant test and the one way to do this efficiently was to use a battery that would keep the circuits closed at all times except when opened by the signal wheel of a fire alarm box. Experience proved that the “Gravity” or “Bluestone” type of battery best served this purpose at that time, and therefore it was universally adopted. Later on the Storage Battery was perfected so that it was practicable to use it for commercial work and gradually the fire department officials began to substitute it for their gravity battery because of its cleanliness, efficiency and economy, but even to-day a large percentage of fire alarm systems are still operated by the bluestone, copper and zinc battery. The main reason for this is because of the initial, cost of a storage battery plant. Cities and towns have for years been appropriating a certain amount of money for fire alarm battery maintenance and when a storage battery plant costing about three to four times this annual appropriation is proposed, the mayor and aldermen generally get up and holler, “Extravagance, can’t afford it, etc.” This is because they have not gone into the matter thoroughly or have been wrongly informed by people who were not in a position to give proper advice on the subject. On the other hand, people who have given the matter serious attention and have gone into the comparative cost, cleanliness and efficiency are unanimous in their decisions that Storage is cleaner, more efficient and, what is more important, decidedly less expensive to maintain, especially under present war conditions.

For the benefit of those chiefs who are still using gravity battery, the following example of comparisons is submitted. This is an actual case that came up the first part of this year. Since that time both gravity and storage battery material has gone up in price, but the comparison at this date would be practically the same. This town in question had 185 cells of Gravity Battery and the estimated cost of maintenance for the year was made up as follows: 370 Zincs (2 per cell per year) at 75 cents each, $277.50; 100 Coppers, at 15 cents each, $15; 1600 pounds Bluestone, at 18 cents per pound, $288. Total, $580.50.

Now the only fair way to compare the two types of batteries is on a basis of cost for a period of ten years because the storage battery elements will not require replacing for at least five years and at the end of that time it is only necessary to purchase new plates which will run the system for another period of five years, the switchboard, rack, motor generator, set, etc., included in the initial cost being good for many years to come. Therefore for the purpose of comparison we will say that for this particular town the Gravity Battery maintenance would cost them for a period of ten years $580.50 x 10 or $5,805.

On the other hand, the initial installation of Storage Battery would have cost this particular town as follows: 1 Four circuit switchboard, $787.50; 1 Battery rack, $89.25; 1 Motor generator set, $147; 1 Protector Board, $36.75; 186 Cells of Storage Battery at $1.69 each, including glass jars, porcelain covers, electrolyte and elements, $314.34; Installation, $175. Total, $1,549.84.

At the end of five years, it would only be necessary to buy 186 new storage battery elements at a price of $1.50 each, or $279. These would be good for five years more of service. There should also be added to storage battery expense the charge for operating the motor generator set which in this instance was quoted by the local lighting company at a flat rate of $15 per year or a total of $150 for the ten years, thus it will be seen that the storage battery equipment would have cost in ten years $1,978.84 against gravity battery cost of $5,805 which means that this particular town will save in ten years time $3,827.16 on the maintenance of their fire alarm battery by substituting storage for gravity. There is also the question of efficiency to be considered. I think that any chief who has ever had anything to do with gravity battery cells will have noticed that his battery is never the same strength, that is, when the battery is newly made up, the voltage of the cells is comparatively low. As the cells work up, this voltage gradually gets greater until it reaches a certain point, after which time the voltage will again start to decrease until it is necessary to renew the bluestone and probably the copper and zinc of the cells. This means that on account of the fluctuating voltage of the gravity battery, there is never the same current flowing into the fire alarm circuit. It is therefore necessary to constantly adjust all alarm apparatus on the circuit to meet this condition. With storage battery, the voltage is constant and therefore the fire alarm circuit is getting the same current flow at all times and once the alarm apparatus is adjusted, it need never be necessary to change it. The question of cleanliness should also be considered. Those chiefs who have had the pleasure of cleaning a gravity battery set will agree with me, I am sure, in my statement that it is a tough job. In the comparison of cost between storage and gravity battery, we did not take into consideration the cost of labor for cleaning the gravity battery. It means a lot of labor to clean a set of gravity batteries and, further than that, they take up a great deal of room which could be devoted to some other purpose. With the storage battery cells, there is none of this disagreeable cleaning incidental to gravity battery, and they take up much less room, a battery rack 60 inches long by 17 inches wide having a capacity of 160 cells and a rack 90 inches by 17 inches having a capacity of 240 cells.

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