Battery question

[mick]

What is the connection, if any, between cold cranking amps and Ah. My car battery just says 570 cca, while my boat starter battery says 48Ah. Which is more powerful, or is that just another indication of tecnical confusion in the already confused elderly. I also have trouble understanding DNA, but that's another matter.

 

[spannerman]

Your boat battery can deliver 48 amps for 1 hr or 1 amp for 48 hrs theorectically.
Your car battery can deliver 570 amps from cold for a specific period of time which eludes me, but someone will put me right no doubt.

 

[Danny]

There's really no connection. CCA relates largely to the internal resistance of the cells in the battery, and therefore the maximum current that can usefully be delivered without the voltage dropping or the plates getting warped. Ah is the amount of electricity that can be stored in the battery. If it says 48 Ah then it can deliver1 amp for 48 hour (or 2 amp for 24 hours, etc) . In practice reckon on maybe 2/3 of this value when calculating what you need.

 

[hubert]

Cold cranking current is the maximum current that can be drawn from the battery at minus 18 degrees for a period of 10 seconds without the the voltage dropping below 7.5 volts. It is not directly related to battery capacity.

 

[Talbot]

While everybody else has shown that CCA and amp'hr are different, perhaps a slightly more user oriented answer will assist in understanding.

A car/ or boat engine is not interested in producing a little power for a long period, but rather in producing a powerful current through the starter to enable the engine to start. Thus a battery suitable for this task is measured in the CCA (cold Cranking amps) to show how much power is available for the starter.

The battery for the domestics is designed to produce a small amount of power over a long period, thus numbers of amps/hr is the correct terminology. The domestic battery is designed for this style of power production, and to use it for engine start will damage the cell walls as it is not designed for such high current flows. However, to use a engine start battery for domestics is also wrong, cause they are not designed for deep cycling and recovery.

Thus if a battery capability is quoted as CCA it is probably designed primarily as an engine start type, whereas an amp/hr rating means it is probably capable of some form of cycling.

There are some hybrid types that can do both (e.g. carbon fibre reinforced plates on the Elecsol range)

 

[boatone]

[ QUOTE ]
There's really no connection. CCA relates largely to the internal resistance of the cells in the battery, and therefore the maximum current that can usefully be delivered without the voltage dropping or the plates getting warped. Ah is the amount of electricity that can be stored in the battery. If it says 48 Ah then it can deliver1 amp for 48 hour (or 2 amp for 24 hours, etc) . In practice reckon on maybe 2/3 of this value when calculating what you need.

[/ QUOTE ]

Better to work on only 35% of stated value as , in practice, you are unliklely to charge much better than 85% and ideally dont want to go much below 50%.

 

[andy_wilson]

Battery answers look OK, so, DNA...

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus. All known cellular life and some viruses have DNAs. DNA is a long polymer of nucleotides (a polynucleotide) that encodes the sequence of amino acid residues in proteins, using the genetic code: each amino acid is represented by three consecutive nucleotides (a triplet code).

In eukaryotic cells, such as those of plants, animals, fungi and protists, most of the DNA is located in the cell nucleus, and each DNA molecule is usually packed into a chromosome and shaped as a double helix. By contrast, in simpler cells called prokaryotes, including the eubacteria and archaea, DNA is directly in the cytoplasm (not separated by a nuclear envelope) and is circular. The cellular organelles known as chloroplasts and mitochondria also carry DNA. DNA is thought to have originated approximately 3.5 to 4.6 billion years ago. [1]

DNA is responsible for the genetic propagation of most inherited traits. In humans, these traits range from hair color to disease susceptibility. The genetic information encoded by an organism's DNA is called its genome. During cell division, DNA is replicated, and during reproduction is transmitted to offspring. The offspring's genome is a combination of the genomes of its parents. Lineage studies can be done because mitochondrial DNA only comes from the mother, and the Y chromosome only comes from the father.

In humans, the mother's mitochondrial DNA together with 23 chromosomes from each parent combine to form the genome of a zygote, the fertilized egg. As a result, with certain exceptions such as red blood cells, most human cells contain 23 pairs of chromosomes, together with mitochondrial DNA inherited from the mother.

 

[temptress]

Re: Battery answers look OK, so, DNA...

Get a life man!