Guys: I've been looking at batteries or my sedan and have a question. I've not thought much about this in the past but I am reading about cold cranking amps. Some say a battery with big cca's will turn an engine longer while some say it will turn an engine "faster". What's the truth about cca's? Tim
Unless you have a very high compression engine I wouldn't worry too much about CCA. I concern myself with it when buying a battery for my trailer, usually a deep cycle. Size to fit what you have to place it is most important. We run pretty small Odeseys with 14-1 engines, good starters, and charging systems. One we've had 9 years racing only 7-10 times a year and never had a failure. As I remember my Sears installer days anything over 500-600 was good but now you can get them double that. Your weather also is a factor. Don't over engineer it and good luck.
One corollary to Murphy's Law is "anything used to it's full capacity will break". I tend to think that way when I choose appliances, including batteries. If everything is always optimal, such as engine tune, electrical system components, etc. 'just enough' may be sufficient....until it's not. I look for the highest CCA and amp hour rating I can find within the group size dimensions that fit the space available for the battery. Ray
The speed the engine cranks at is related to the voltage available. The voltage available to the starter motor depends on lots of things, and CCA is one of them...but only to a limited extent. There is voltage drop at the battery because of the load on it, voltage drop through the wires, varying load on the starter (because the engine takes a varying amount of torque to turn it, as each piston is on the compression stroke), etc. If the battery has way more CCA than needed to crank the engine, it won't spin faster with a more expensive battery.
As I recall from long ago days working in a dealer shop, we would run amp draw tests on starters to, at least in part, evaluate their condition. I suppose I think if a starter system is drawing greater current than ideal, a higher amp battery can deal with that, at least for awhile. In any case, whether right or wrong, I have the notion that reserve capacity is generally a good thing. Ray
the no load current draw of a motor will tell you something, but not a whole lot.... What they do under load is good to know.
As I recall, it was under load that we tested them. We had a SUN two gauge device....one side was a carbon pile load tester to draw test a battery or generator....the other was a high capacity amp meter to see what the amp draw was when the starter was engaged. Ray
CCA has nothing to do with reserve capacity though, and "best" is not necessarily the one with the highest CCA. Very common misconception. The problem generally, is that when the temperature goes down, the internal resistance of the battery goes up. Consequently the ability for the battery to provide current goes down under those conditions. At the same time, in cold weather conventional motor oils turn to sludge, and the resistance to turning over increases. Battery manufacturers increase CCA or "cold cranking amperes" by increasing the surface area of the plates. More plates. Thinner plates. So for a few seconds the battery can provide more current. This higher CCA, desirable or necessary in cold states like North Dakota comes at a cost, in any given battery group size, it will have less reserve capacity and the plates are prone to breakage and earlier failure, shorted cells etc. The takeaway is, if you don't need the extra CCA don't buy them. It's a waste of money and it will likely fail much sooner. This is especially noticeable in southern states where battery life is considerably shorter to begin with. Within any given group size, the heaviest battery is the one you want, once minimum cold cranking amps is met. This is a lot lower than people think. One rule of thumb used to be one CCA per cubic inch of engine size, not counting diesels of course, or high compression engines.
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