DieHard Marine Deep Cycle/RV Battery

[Ron]

Saw the Sears DieHard Marine Deep Cycle/RV Battery, Group Size 24M Model 27494, specs are as follows: CCA: 500 - AH: 80 - RC: 135, on sale for $59.99.

The battery box in my 2002 Dodge - 2002 RoadTrek is approximately 10 1/2" long by 10" high by 14 1/4" wide, the 4 corners of the box are opened, 2 corners there is a wide opening gap top to bottom, well vented.

I have been told this battery would be OK to use, wondering if others have used this battery.

Ron

[Ron]

I just had two (2) Sears DieHard Marine Deep Cycle/RV Batteries, Group Size 24M, Model 27494 batteries installed at my local Sears, cost $69.99 each, specs are as follows: CCA: 500 - AH: 80 - RC: 135.

We don't do any dry camping, do use the refrigerator when traveling as I don't care to use propane when driving.

For what I use it for these batteries are good enough for me, the battery storage box which is underneath the floor holds only 2 of the group 24 batteries. The storage box is well vented.

I am satisfied.

Ron

[markopolo]

That's a nice upgrade Ron.

Two batteries are better than one. Basically they share the load. For example, say your are drawing 20 amps. With two batteries each will be contributing 10 amps. Less amp draw is easier on the battery.

Peukert's Law, presented by the German scientist W. Peukert in 1897, expresses the capacity of a lead-acid battery in terms of the rate at which it is discharged. As the rate increases, the battery's available capacity decreases.

Link: Wikipedia - Peukert's law http://en.wikipedia.org/wiki/Peukert%27s_law

Basically higher amp draw is harder on the battery. Spread the load amongst two or more makes it easier on the batteries and they last longer (both on your trip and in terms of lifetime)

[Mike]

Isn't that like saying (glass of water analogy) " the faster I pour, the emptier it gets"? DUH!!!!
(I know, I'm electrically challenged, so, who am I to make fun of German scientists )

Shamelessly, Mike.

[markopolo]

It does read that way......

Mr Peukert devised this formula to illustrate numerically how discharging a battery at higher rates (amperages) actually removes more power from a battery bank than one would expect. This law explains why a battery discharged at 20 amps does not remove twice as much power as one discharged at 10 amps, the battery actually realizes a slightly larger discharge for the 20 amps.

Using your water example - say you had 1 gallon of water and 4 one quart containers. If you pour really slowly your 1 gallon of water will fill your 4 one quart containers. If Peukert's law applied to water pouring and you poured really fast your 1 gallon of water will fill only 3 1/2 one quart containers.

[Mike]

So Peukert was a spilly pourer?
"Energy can neither be created nor destroyed"
In your enhanced analogy, where does that missing 1/2 quart go?
Is it radiated as heat, as static electricity? I would think the all of the potential energy in
a battery would have to be accounted for in order for Peukert's theory to
"hold water"?

[markopolo]

His formula allows you to calculate what the loss will be when you input particular battery specs. It's useful when you need to make sure the battery will perform as needed.

Where do the amp hrs disappear to? I don't know. I'll be looking on the ground for them at my next campsite!

[Mike]

Hahahaha. Good answer.
I'll be holding the kerosene lantern to light the search area.