Keep stored battery cold and charged
THERE are many myths and suggestions about how to store automotive batteries — some based on fact, others fiction.
With fall here, many motorhomes, collector cars, motorcycles and even that special convertible are being put away for the winter months. So what should you really do to help prolong the life of your vehicle’s battery?
One of the best things you can do for an automotive battery is to use it. Putting it into another vehicle that is driven on a regular basis will keep it charged and working properly. Most of us don’t have that option, as we already have a battery in the other vehicle, so we have to place the battery in storage.
One of the myths is that you should always leave a battery connected in your vehicle when it’s in storage. This is incorrect, but there are a few things you should know before disconnecting your battery.
Many vehicles on the market have radio security features and express open and close windows, sunroofs and even doors (on vans). When the battery is disconnected, you may need to reset the systems before they will operate correctly. The radio may need an unlock code. The vehicle owner’s manual will give you information about this, or you can stop by the dealer. If you need a radio code and don’t have it, get it from the dealer before disconnecting the battery or it could cost money later to have the dealer unlock the radio. Newer vehicles use non-volatile memory chips that allow the battery to be disconnected without interfering with vehicle operation. Another myth is that your vehicle will not run as well after the battery is disconnected, although there is a grain of truth here. Your engine and transmission computer adapts to wear and inaccurate component calibrations as your vehicle ages. When the battery is disconnected on some vehicles, the computer goes back to its original program parameters and the vehicle may run a little rough or differently when restarted. However, the computer will automatically adapt quickly as you drive to make the engine run the same as before.
Disconnecting the battery prevents electrical drains from the vehicle’s components from killing the battery as it sits. The battery can be stored in or out of the vehicle, but should be charged every couple of months during the storage period.
One myth says you should never store a battery on a concrete floor. Again, there is a measure of truth here — the concrete won’t discharge the battery, but moisture that wicks through it will create a higher humidity area around the battery that will make it discharge faster. Placing a piece of wood or cardboard between the battery and the concrete allows that moisture to evaporate.
Another myth is that you should store a battery in a warm place rather than a cold one. In fact, it’s the opposite. Chemical reactions occur faster when they are warm, so storing a battery in a warm place will make it discharge faster. Even when in operation, vehicle battery life is shorter in the hot southern U.S. than during cold Canadian winters due to faster chemical reactions. A fully charged battery will not freeze at –40C, so you can store it in a cold place (not the freezer though!) and keep it charged.
As an interesting note, hybrid vehicle batteries have excellent durability but their charging systems only take the batteries to about 80 per cent of full charge. The last 20 per cent creates heat in the battery that shortens its life, so keeping it at about 80 per cent maximizes durability. Charging systems on several of the newest vehicles also let the battery charge drop and then only charge it part-way. This is done to reduce chargingsystem load on the engine and improve fuel economy, but may also extend battery life too.
Do keep the top of your battery clean and dry. Dust and dirt hold moisture, which creates an electrical path between the battery posts and causes it to discharge faster.
Keep it cold, keep it charged and disconnect it when stored for several weeks or longer and you will maximize the life of your vehicle’s battery. Jim Kerr is a mechanic, instructor of automotive technology, freelance journalist and member of the Automobile Journalists’ Association of Canada.