By Norman Nock
Originally published in the Austin-Healey Magazine, December 1983
When your engine will not crank or has a slow labored sound if it does crank, the first thing to check is your battery.
Use a hydrometer to check the available electricity in the battery. Density or specific gravity will show you the state of charge of each cell.
If the cells are not all in the full charge scale, the battery will need to be charged.
Water is taken as the standard basic unit and given a density of 1. Thus in effect we are weighing the electrolyte acid against water. The denser or heavier the electrolyte, the higher will be the hydrometer float, and consequently the reading. Thus for a fully-charged battery, when the electrolyte is most concentrated, we shall have a hydrometer reading of approximately 1280 – this is the everyday method of saying that our acid is 1.280 times heavier than water. This density is usually referred to as the SPECIFIC GRAVITY or “S.G.” fall. You can see how, in the right of the picture, the float has sunk just about as low as a float can sink.
Thus the hydrometer reflects fairly accurately the state of charge of the cell, always providing that the cell is in a normal condition.
Charge the battery with a slow charger for up to 36 hours or until each cell shows fully charged on the hydrometer. If, after a long slow charge the specific gravity does not pass ¾ charge, the battery has reached the end of its useful life.
Continued use of a battery in this condition will cause the corrosive action of the battery acid to damage many parts of your Austin Healey. The white corrosion can be removed and neutralized with household baking soda mixed into a wet past and spread over the corroded area, then washed with water.
When a battery starts to use water regularly it is telling you that it is getting old and is suffering from “arteriosclerosis” (hardening of the plates inside the battery). At this point in its life it cannot stop itself from being overcharged. The excess charge will cause the acid to boil and the gases from this action will cause corrosion.
The white material that accumulates on the battery terminals will travel along the wires and will show itself at the fuse block, gas gauge, tank unit, tach and all other electrical joints throughout your car'’ electrical system. Installing a new battery can only stop this problem.
The charge rate should be checked as per your factory service manual to make sure that your new battery is not receiving too much electricity and adjust as required.
Maintenance Free Battery
This type battery will avoid being overcharged when it gets old. The elimination of traditional antimony from the plate removes four major causes of early battery failure – overcharge – water usage – self-discharge and thermal runaway.
Low Maintenance Battery
This type battery will still suffer water usage and overcharge when it ages because there is still some antimony in the plates.
The gases from a battery will explode violently from a spark, flame, cigarette or any other ignition device.
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