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CCAs
Post by snuffy on Oct 9, 2006, 8:21am
Still torn on the 24V vs 12V question, but have run into a interesting question:
If your batteries are in series, does it double the CCAs available??
I know 24V uses less amps, but doubling them as well????
Hmmm...
Snuffy
Re: CCAs
Post by vrod02 on Oct 9, 2006, 8:32am
I'm steppin out on a limb here so correct me if I'm wrong.I was told 24v was used because lead is cheaper than copper and was need for ammo. Smaller wire can be used in the 24V harness, saving the copper. I know a 6v ford tractor will spin slower but for a longer time than a 12v conv.
Re: CCAs
Post by brute4c on Oct 9, 2006, 9:41am
One does not double the amps when hooking the 2 batteries in series...it double the volts from 12 to 24. If you want to increase cold cranking amps, do what they do in diesel cars...run the batteries in paralell...then you double the cold cranking amps.
The reason normally given for using 24 volts, and higher, is that when the voltage is doubles, the required amount of amps to do the same work is halved...rougly anyway...so something that took 20 amps in 12 volt takes about 10 amps in 24 volt...this means that all the wiring can be of a smaller gauge, switches and relays can be smaller and lighter, alternators dont need to be as large, starter windings are reduced...etc.
For the longest cranking time, you want the most RESERVE...you need a good CCA rating BUT if you have 2 batteries with roughly the same CCA reading and one has a case that is much larger, it will have more reserve capacity and will allow for longer cranking, or drawing, before it stops...the smaller case runs out first...easy to picture...kinda like a large and small gas tank and the engine always draws at the same rate.
Re: CCAs
Post by amphi on Oct 9, 2006, 10:05am
It is all about Ohms Law.
Power is equal to Amps times Volts --- P = I x E
http://www.the12volt.com/ohm/ohmslaw.asp
Re: CCAs
Post by snuffy on Oct 9, 2006, 6:57pm
Thanks guys....
Was reading a Consumer Reports article about batteries and screwed up: I started thinking.
I'm not an electrical junkie, so I figured I'd ask. Dang Ohm and his stupid laws!
Snuffy