Deep Cycle Battery Ratings

quique
quique Solar Expert Posts: 259 ✭✭
in Solar Beginners Corner #1
Im being offered batteries Surrete. The specs are these:

Battery Rolls S530
6V

532Ah in 100h
400Ah in 20h

I remember reading about batteries and how the important number (so to speak) was the Ah rating at or near 24h. Id like to clear that up a bit. From what I understand, the ah rating is how many amp hours a battery can produce during that alloted time, so:

During a 20h period, this battery can supply 400Ah

or

During a 100h period, this battery cans supply 400Ah

It almost seems counterintuitive because how can a battery supply MORE Ahours over a longer period of time? So i searched for the specs and sure enough, found this:

Attachment not found.

The table shows exactly that pattern where Cap/AH increases with Hr rate, so I must be reading this wrong. Then the right column reads something that makes more sense, during 100 hrs it can supply 5.32amps whereas during 1hr it can supply 144 amps. So why am I reading it wrong? :)

On the other hand I looked at an Optima BlueTop which has these specs:

Attachment not found.

This shows this battery's Ah rating at:

55Ah @ C/20.

And then Trojan has the following:

Attachment not found.

Where their batteries are anywhere between:

33-140 Ah at 20hr Rate.

So I imagine that the Surrette, which is a battery made specifically for RE systems, it makes sense to have 400Ah at 20Hr. I understand its quite a heavy battery and it costs around $300.

The Trojan is also known for RE systems so if it doesnt go past 140Ah at 20Hr then its because they dont consider themselves solely a RE battery maker.

Finally is that why Optima, which makes a lot of regular starting car batteries, simply has a 55Ah at 20Hr and not much more?
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Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: Deep Cycle Battery Ratings
    quique wrote: »
    532Ah in 100h
    400Ah in 20h

    That means that the battery can provide 5.32 amps for 100 hours. Or the battery can provide 20 amps for 20 hours. For most (all?) batteries the slower you discharge them, the more AmpHours you can get out of them.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • quique
    quique Solar Expert Posts: 259 ✭✭
    #3
    Re: Deep Cycle Battery Ratings

    Oh ok I see the missing math!

    532Ah / 100h = 5.32a for 100 hrs
    400Ah / 20h = 20a for 20 hrs
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #4
    Re: Deep Cycle Battery Ratings

    Now your cooking with Crisco....
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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