As with many things just like our human bodies, extremes kill things. Too hot, your battery will lose water and lose charging capability leading to sulfating (rendering the battery useless, in many cases, permanently). Too cold, and your battery loses capacity, i.e. Cranking Amperes.
If the car is kept outside in temperatures below freezing, you should consider the following:
- Engine Block Heater
- Battery Blanket/Heater
- Battery Maintainer
- Charging System Maintenance!
Engine Block Heater:
Why is it important? The coolant in your motor is susceptible to freezing. Even if you use high concentrations of Anti-freeze, it will eventually freeze. A 50/50 ratio is good down to -34°F (-36.7°C) Your oil also thickens at below freezing temperatures an this certainly does not make it easier on the electrical system to turn the motor over. Cold, thick oil means high internal resistance which in turn results in increased demand on the electrical system increase the amp load that the battery must supply to turn the motor over. With an already weakened battery due to the cold, this is among the #1 reason why batteries (and starters) die in cold weather. A block heater helps alleviate this issue by keeping the motor at a warm temperature. This works wonders on several levels:
- Decreased Engine Wear (Cold starts are where the majority of engine wear occurs - Even when temperatures are above freezing - Tolerances in the motor are tighter, which results in increased wear.)
- Reduced demand on the vehicle's electrical system (A warm motor turns easier. Rest your poor starter and give it a hand.)
- Your heater will work much more quickly and result in less strain on the vehicle while it is warming up
Why is this important? In most cases, you probably have what is called a "Flooded Cell Lead Acid Battery". There is an electrolytic medium of Sulfuric Acid and water which fills the battery cells in between suspended lead and lead-oxide plate electrodes. For simplicity's sake we will not break down the functions of the battery to it's operating principal (you can learn more by checking this video out: https://www.youtube.com/watch?v=rhIRD5YVNbs) but, cold weather increases the internal resistance and reduces it's capacity. A battery blanket/heater works just like an engine block heater except for your battery. There is a reason why automotive batteries are also measured in CCA (Cold Cranking Amps).
Why is this important? Remember the discussion regarding increased internal resistance and lowered capacity? Parasitic draw on the battery will kill it in short order come winter. A battery maintainer coupled with a blanket/heater can be the difference in being able to start on a cold day or not. These typically work to reverse sulfation, and keep the battery in overall good health. The best part is, every morning you get a FULL charge. If your vehicle is run on short low speed trips, you may not be charging the battery fully. The battery (typically) only really charges at highway engine speeds because the alternator needs to turn fast enough to generate the current needed to supply the electrical components in the vehicle as well as recharge your battery.
Charging System Maintenance:
Why is this important? Your battery/cranking/charging system is only as good as its weakest link. Consider that you have not maintained the Water level in your cells (unless of course your battery is Maintenance Free, or AGM (Absorbed Glass Mat), LiFePo4 (Lithium Iron Phosphate), Li-Ion (Lithium Ion) or other maintenance free chemistry batteries) This means higher rate of sulfation, as a result, higher internal resistance, and therefor your alternator cannot recharge the battery fully, or may not be able to charge the battery at all. In fact, a bad battery accounts for a large portion of failed alternators. They overheat the diode circuity attempting to maintain the voltage required to charge the battery, overheat the battery as a side effect, and can even cause fires or explosions from the production of hydrogen gas in severe instances. Maintaining your charging system is the difference between needing a jump in the morning or being able to get a reliable start every time.
- Keep your battery terminals and terminal posts clean. Any corrosion should be cleaned off and neutralized with a baking soda and water solution and a steel wire brush. (DON'T LET THIS GET INTO YOUR BATTERY THOUGH, IT WILL KILL IT IN SHORT ORDER!)
- Replace any old, frayed, torn, or corroded wire. Bad grounds, bad positives, all result in higher internal resistance, ineffective charging, or ineffective transmission of voltage to your starter. Keep them in good condition and you'll notice a difference right away. Old wires tend to get brittle and increase in resistance over-time (mainly due to oxidation). It's always a good idea to change old cables.
- Keep your battery hydrated (if required - not all cars use flooded cell batteries as "Maintenance Free" AGM Batteries have become popular OEM equipment on most vehicles these days) A poorly hydrated battery will not charge, will discharge, and will leave you stranded. Simply pop the covers of your battery cells (Wear Goggles and Acid Proof Gloves (with sleeves!) and check if they are just below the fill tubes. If it's lower at full charge, you need to rehydrate the battery. Using a battery filler bulb GENTLY add Distilled (ONLY - Any other type will introduce contaminants which will shorten the life of the battery significantly) water. How can you make sure your battery is fully charged and healthy? Your local autoparts store can help with testing the capacity and health of the battery with a load tester tool. Don't trust them? Get a battery "hydrometer", a multimeter and compare the "Specific Gravity" of each cell to the voltage of the battery. The battery voltage at rest should be around 12.63V DC at 100% charge. The specific gravity should be near 1.265. Any deviation indicates a loss of capacity.
And at worse case, especially if you're uncomfortable with checking your battery's gravity (don't feel bad, it's not for everyone!), take it to your trusted Mechanic for a pre-winter checkup. They can spot these issues and resolve them before you end up having to continuously buy new batteries and starters.
Cold Weather Starting Tips:
- Turn your key to the "ON" position and wait a few seconds. In the case of a fuel injected gasoline car, this primes the fuel pump and pressurizes the fuel rail. You may sometimes hear a whine or whirr from the vehicle for a few seconds. This is normal, and wait until it stops, then crank the vehicle. This ensures that you get a good flow of fuel to the motor, reduces cranking time, and reduces battery demand.
- Turn off your lights/heater/radio/electrical drawing appliances! The last thing your battery needs is additional load when it's already operating at a reduced capacity! It needs all the help it can get so give it a break and save it the weight.
- (Carbureted Vehicles Only) Use the choke, and pump a few pumps of fuel into the engine prior to starting. Every car is different and will need different finesse to start. A freshly rebuilt and tuned carburetor will ALWAYS start easiest.
- (Diesels Only) Many Diesels have "Glow Plugs" or "Grid heaters" and sometimes BOTH! These work to make cold starting easier. Diesels NEED heat to run, so it's extremely hard to start them in cold weather. It's imperative you let these heaters reach full temperature before you try starting! Otherwise you're wasting battery, and hurting your starter! Turn the key to on, you may see a "Wait" light or hear a buzzer (not to be confused with the "Low Air" buzzer on commercial vehicles). Wait for it to turn off before starting your vehicle.
- DO NOT crank your vehicle endlessly. You are just wasting battery. If the vehicle does not crank within a few seconds of starting, STOP. Turn the key off, let the battery and starter recover, and try again. This can especially happen if your engine is worn, or in poor condition. Keep your ignition system in top shape for quick starts!
- REFRAIN FROM USING STARTER FLUID IN EFI VEHICLES! Not only can this contribute to oil dilution (extremely rich fuel mixture), it can damage the sensors required to run your engine properly.
- DO keep your battery fully charged and charging system in good condition. Even a little corrosion can result in a no start situation!