Caring for Tyres and Batteries in the Cold

When the rain, the cold and the snow cometh, a reliable well maintained vehicle is more than desirable, and any weaknesses, particularly in the battery and tyres soon become apparent.

Going into the worst of winter, for safety’s sake you should cheek your tyres to ensure there is a good depth of tread all round. On icy and wet roads, a bald spot on a tyre could give you a quick trip to somewhere you did not expect to go, with sometimes disastrous results. And if the replacement of your tyres is about to fall due, this is the best time of the year to fit new ones. Research has shown that tyres which do their first few thousand miles in the cold of autumn and winter actually last longer than new tyres fitted in summer.

It is also wise not to over-inflate tyres at this time of year as this could reduce the amount of tread meeting the road. If you are likely to be driving through snow and will be fitting chains, remember never over-inflate or under-inflate tyres to make them fit the “chain. The chains are designed to creep on a tyre so they will not gouge the rubber, so make sure you have bought the right size and that they are not fitted too tightly. And of course, never drive with chains on bare roadway as this will ruin both the chains and the tyres.

But it is your vehicle’s battery which needs the most care and attention in winter time. A flat battery on a cold wet night is one of life’s more unpleasant problems, so ensure your battery will last through the winter without letting you down. A simple test with a cheap hydrometer will tell you the approximate condition of your battery. A hydrometer gauges the strength of the electrolyte in the battery’s cells by measuring the specific gravity of the acid, in other words, the weight of the electrolyte as compared to the weight of pure water, As the failure point is approached, the difference in the specific gravities of electrolyte taken from the various cells widens. If the readings from each cell vary significantly your battery has outlived its usefulness and should be replaced. There is a knack to using a hydrometer. Be sure the float rides free, read the recording off the scale and return all the electrolyte to the cell from which it was drawn. If the reading is lower from any one cell than the others, then it is probable that cell is weak and the whole battery will soon fail.

A battery’s state of charge is usually expressed in terms of a percentage of the full charge it is capable of holding. To determine its state of charge you should know its full-charge capacity, and any dealer should be able to tell you. If you add up all the specific gravity readings from the cells,’ and divide by the number of cells, you will be able to calculate how close to full charge your battery is. If it is below fifty percent charged, have it recharged and then test it again. Recharging should be done by trickle feed and take at least 24 hours. If after recharging the readings still do not exceed fifty percent charge, replace the battery. However, if it recharges to more than fifty percent, check your car’s electrical system to find out what has been draining it and that the generator or alternator are functioning properly. A cold wet night is not the time to find that a short in the cigarette lighter has been taking the life out of your battery.

Of course no battery holds its charge indefinitely and there will be a steady drain because of chemical action. Recharging from time to time is important to prevent battery sulphation, which is the hardening of the lead sulphate. When this occurs it affects the conversion of the plates back to lead and lead peroxide and this lowers the battery’s capacity. A common cause of discharge you can prevent is external leakage of current. Dirt or spilled electrolyte on a battery’s case provide a conducting path through which a battery can discharge itself. To prevent this, clean your battery with a baking soda solution (keep the solution out of the cells) and scrape and sandpaper your terminals so they are bright and clean. Make sure you flush the baking soda solution off the case with clean water.

It is also important to keep your battery cables clean, tight and in good condition. A weak cable can leave you stranded even when your battery is in tip top condition. A coating of vaseline on battery terminals and cable ends can help prevent the build-up of corrosion which also affects your battery’s output. The high sulphuric acid content in the electrolyte acts as a battery antifreeze. In freezing cold weather you should not add more water to your electrolyte unless you will be travelling far enough to ensure it is well mixed with the electrolyte. Newly added water tends to remain at the tops of cells and will begin freezing at 0 degrees centigrade.

If your battery does ever freeze up, more than likely your car won’t start. Take the battery out of the car, put it in a warm place for about 12 hours, fill the cells with water and charge it up again before putting it back in the car. A fully charged battery at freezing point delivers only 65 percent of the cranking power available at 25 degrees. During heavy frosts the cranking power delivered can drop as low as 40 percent. So in an emergency you may be able to persuade your sluggish battery to deliver enough charge to get you started by partially immersing it in a hot bath for a while before trying again.