Post by
Larz »
https://forums.nicoclub.com/larz-u216291.html
Wed Oct 23, 2013 2:48 pm
It's all about chemistry and physics, mates.
The car battery contains an anode, a cathode, and electrolytic ions. Simply stated - think of a tub of water with a positive end (cathode) and a negative end (anode) and consider the bath water as an electrolyte solution full of electrons.
The chemical reaction in the battery causes a build up of electrons at the anode area. These electrons naturally need to rearrange themselves to get rid of this "difference" so they are constantly in motion, inside that solution, trying to get to a place with less electrons.
In a battery, the best place for them to go is to the cathode end. BUT, the electrolyte solution keeps the electrons from going straight from the anode to the cathode within the battery. Like you trying to swim from one end of your pool to the other, but the pool is filled with molasses instead of water.
Once you connect a wire from one terminal on the battery through any circuit ( a lamp, a car starter, etc) and run it from that circuit back to the opposite terminal on the battery, the electrons have a fast, easy path to get to the cathode and they fly through that circuit instead trying to 'swim' through molasses. To keep that reaction from flowing 24/7, we use switches / fuses that open or close the pathway, thus trapping the electons inside the battery when not needed. In the case of a car, the alternator is responsibe for charging, or replacing the charge on those electrons as they pass through the battery.
Any battery can die at any time, but in winter, they suffer from the "Cooling Affect". As you know, just about any chemical reaction (like the one in your battery) will run faster with heat and slower with cold. The outside temp affects the available charge from your battery while it sits. A new battery at 80 degrees has 100% charge, at freezing temp (0c or 32F) it's reduced to about 3/4 charge, and below freezing, it can drop to 1/2 of full charge.
Add to that, the work placed on the battery in winter - running a defroster, a car heater, seat heaters, and increased headlamp usage (its dark early in winter). Even with a good alternator, there may not be enough drive time to replace enough 'charge' inside the battery for it to run the starter motor the next morning.
Similarly, too much heat is also bad. High temps can cause the solution inside the battery to evaporate, and it's the soluiton that gives the battery it's ability to accept and keep a charge from the alternator.