Car Battery Specifications
When working on your car if you have to do anything involving the battery, you’ll find out what they mean (car battery specifications) and how they impact what you’re trying to do.
A standard 12 volt cranking battery has 6 individual cells. Each cell is designed to produce ~2.1 volts. The cells are connected in series for a total of about 12.5 volts. Each cell basically consists of 1 set of lead plates and 1 set of lead plates coated with lead dioxide submerged in a sulfuric acid electrolytic solution.
Car Battery Specifications
The level of the electrolyte should be about 1/8″ below the bottom of the filling wells. If the electrolyte is above the bottom of the well, it may be forced out when the battery is charged. If the electrolyte is allowed to fall to below the top of the plates, the battery will be damaged. If the level of the electrolyte is low, refill it with distilled water only. Regular tap water has minerals which may coat the plates and reduce the battery’s capacity.
Distilled water is water that’s been heated to cause it to evaporate into water vapor. The water vapor is then condensed back into liquid water. The distilled water is free of all impurities including minerals that would coat the plates of the battery and therefore reduce its capacity to produce electrical current.
Cranking amps is the spec that tells you how much current a battery can produce for 30 seconds at a temperature of 32° F and not have the voltage on any of the individual cells drop below 1.2 volts (7.2 volts for a 6 cell automotive battery). This may also be known as MCA or marine cranking amps.
Cold Cranking Amps:
This is the same test as cranking amps but is done at 0° F. The CCA spec is especially important if you live in a really cold climate. Since the chemical reaction that produces electrical current in the battery slows down as the temperature drops, the battery can produce less current at colder temperatures (especially below freezing). When comparing the current capacity of batteries, make sure that you have some standards to qualify the current ratings. If you see the current rating without CA or CCA, you don’t know how the battery was tested and the current rating is virtually useless.
The reserve capacity is the time that a battery can produce 25 amps at 80° F before the individual cell voltage drops below 1.75 volts (10.5 volts for a 6 cell automotive battery).
Deep Cycle vs Standard Battery:
1. A normal lead-acid battery will be damaged if it is completely drained (even if it’s only one time).
2. A deep cycle battery is designed to survive being drained multiple times.
3. Deep cycle batteries have more reserve capacity but have less cranking amps for a given size.
4. A standard battery would have more total surface area on its plates when compared to a deep cycle battery of equal size. This extra surface area provides more area for the chemical reaction to take place and therefore produce a higher output current.
5. The electrolyte in a deep cycle will be a slightly more concentrated sulfuric acid than a standard battery.
Gel-cell batteries use a thickened (gelled) electrolyte that will not leak out like a liquid electrolyte. Many of them can be mounted in virtually any position. These batteries may be suitable for some applications but for engine starting, other batteries should be used. Gel-cell batteries can not produce as much current for long periods of time as standard liquid electrolye batteries.
Recombinant Gas Batteries:
RG batteries have only 2 long thin plates per cell. They are constructed much like an electrolytic capacitor. The plates are separated by a fiberglass mat material designed to hold the electrolyte. These long thin plates have significant amounts of surface area (compared to standard batteries). This extra surface area allows the battery to produce significantly more current than standard batteries of similar physical size. Optima® is one manufacturer of RG batteries. If you’re going to add batteries to your system and the batteries will be in the vehicle’s trunk or passenger compartment, RG batteries won’t vent flammable hydrogen gas or corrosive gasses into the vehicle.
The battery group size is an indicator of the battery’s physical dimensions.
for example one of my vehicles uses a group 48 battery 11 x 6-15/16 x 7.5 (top terminals, and clamped near bottom of battery.)
the other uses a group 75 9-11/16 x 7.25 x 7.25 (side terminals, clamp goes over top of the battery)
Another vehicle uses a group size 24 battery but a group 35 fits without an issue. I could probably put about anything in assuming it fits, since the hold down goes over the top of the battery. I know because I had to get a new battery and when I researched what I should put in it, the databases said a 24F (the F indicates the terminal orientation) yet the battery I pulled out was a group 35. Since the climate here is mild and CCA aren’t that important, I just get the least expensive one.
If you have a recent vehicle, the electronics may have a security feature where if power is removed you need to input a security code before you can use it after disconnecting the power. Here is something you can try connect a small power supply to a power connector and plug it into the cigarette lighter plug. Providing power may trick the electronics into not knowing the battery was removed. It worked for one of my vehicles(98 suburban), but not the other(’04 Acura MDX)
When removing the old battery, the first thing you should do is to disconnect the ground connection (assuming that that is the connection that attaches to the car chassis). this is so if you inadvertently touch the chassis with the wrench while it is touching the positive terminal you don’t start arc-welding.
Now disconnect the other terminal
disconnect the hold downs