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Battery - does size make a difference?

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ichthos

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Does it make a difference what size the batter is? The larger the battery, the more amps, correct? A shop near me said the closest he could get is 5x9" and 8" high that would fit in the cheap tray I bought from AH spares. This seems a bit small to me. Thoughts?
Kevin
 
Does sound a little small to me, but probably would be OK. Yes, the larger the battery, the more current it's capable of, and the greater the capacity (think length of time you can crank it) as well. Generators don't keep the battery really well charged, and are OK for the stock configuration, but not if you have extra electrical stuff. So, you depend on the battery a lot.
 
Group 24 is correct for 58-67, 68 on takes a smaller battery, Group 27 I think, not positive. Same as a Honda Civic from the 80s
 
Sarastro said:
Does sound a little small to me, but probably would be OK. Yes, the larger the battery, the more current it's capable of, and the greater the capacity (think length of time you can crank it) as well.
Click to expand...

Actually, that's a very common misconception. It all depends on the number of plate in the battery. Group 26 ( the small old top post) usually has more plates, CCA and reserve capacity than the larger group 24. Group 75 is a good example of neither. It's more powerfull than both the smaller group 70 and the larger 24. This comparing apples to apples ( same brand and month) and common auto batteries, not BIG trucks.

I believe the 51 is hotter than both the 24 and 26 ( the "new" smaller Honda battery). Most modern smaller battery sizes have way more power than the older 24 and 26 due to more electronic equipment on newer cars. Just look at the top and compare the specs to what you have now and what you are looking at. Old rule of thumb was one CCA per cubic inch on old smog cars. A riding mower battery will spin these things fine ( as well as my 360 V8 Jeep truck. :wink: )

I sold a ton of 26's and had a hard time convincing folks it had more power even after they read the specs. It's counterintuitive, but it's true. A smaller battery can and usually does have more power and reserve. Group 27 and above that rule doesn't hold well.
 
One last thing, the battery in my jump box is a motorcycle battery that has 900CCA's and is half the size of my riding mower battery. Only the most serious 24's have that much power, then again, it's a $129 jump box.
 
I am confused by what you guys are saying. If all car batteries are 12 volts, how can the plate numbers change? I know my understnding of batteries is very basic, but it used to be that one voltaic cell in old fashioned batteries were made up of two plates. The number of cells (made up of two plates) equalled the number of volts. For example, a standard 12 volt battery would be composed of 24 plates. The size of the plates determined the amount of amperage. The larger the plates, the greater the amperage. I know there is some variation in this, depending on what metals are used because it is compared to earliest batteries made up of zinc and copper. For instance, when you go to the store to buy a flashlight "battery" (actually one voltaic cell) it is listed as 1.5 volts because the of different elements being used, and the resulting difference in electronegativity. Can someone explain this to me more?

On a more practical level, since the only thing really changing is the amperage, is there some rating that tells you the amperage of each battery? Is the amperage then the reason for the difference in prices? Any help in explaining this would greatly be appreciated.

Kevin
 
Big batteries weigh a lot more than small batteries (sometimes I get real technical) :wink: ...so, I chose a little 51 battery that is 500 cold cranking amps. Every bit of weight saving helps out with performance, and I do not drive my car much in the sub zero weather. As long as the car is well tuned it does not take much to start it. Maybe if I had a high compression engine I'd feel differently.

When my midget was a daily driver, I did have a larger battery because it was parked outside over night and it was using a generator at the time.
 
ichthos said:
I am confused by what you guys are saying. If all car batteries are 12 volts, how can the plate numbers change? I know my understnding of batteries is very basic, but it used to be that one voltaic cell in old fashioned batteries were made up of two plates. The number of cells (made up of two plates) equalled the number of volts.
Click to expand...

Each cell in the battery is about a bit over 2 volts, depending on how it's charged, so you get around 12.5-13V for six of them in series. Each cell can consist of a number of plates, interconnected; you can have more than two.

The current capability depends on the total plate area of each cell. I was assuming that a larger battery would have more total plate area, since there's obviously more room for the plates. But I suppose you can squoosh more plates together enough, in a smaller cell, so that it doesn't make so much difference.
 
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