12v vs 24v agm ah vs voltage etc

I think I have this down via experience and a whole lot of study.

With FLA's  you limit bulk charge current "letting" them charge instead of forcing them to charge. Correct?

With AGM's this limit is still enforced but they can absorb much faster so this limit is much higher. Correct?

So a 100ah FLA at C10 is limited to 10 amps and a 100ah AGM at C5 is limited to 20 amps. Correct?

- Jeff


  • Marc KurthMarc Kurth Posts: 417Solar Expert ✭✭✭✭

    Remember that the battery will dictate its own amperage draw depending upon the voltage being fed to it. The higher the voltage that you feed it, the higher the current that it will demand.

    Simplistically, you push voltage to battery and it pulls amperage depending upon that voltage.

    A healthy battery sitting at low charge will want to pull LOTS of amps when you apply the charging voltage.
    In fact, many batteries would draw so many amps that they would damage themselves and the charging system if allowed to.
    To avoid this, the charging system will modulate the voltage to just the right level to cause the battery to reduce its amperage draw to whatever the maximum is.

    As the battery fills, it draws and less amps. At full charge, a healthy battery will draw very, very little amperage.

    Be careful with the broad brushstrokes of Flooded and AGM. The difference between brands is astronomical!
    One brand of AGM has a maximum charge rate 20% of the battery 20 hour rating. Exceeding that will rapidly cook it.
    Another can take 300% to 500% of the battery 20 hour rating. (Yes, that is 300-500 amps on a 100 amp battery)

    Also note the difference in terminology between C/10 and C10. The first is Capacity divided by 10 and the second is Capacity times 10.


    I always have more questions than answers. That's the nature of life.
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