battery amp hours

Two 12v batteries in parallel with 300 a/h rating each.which gives me 600 a/hs.does the 20 hour period also increases from 20 to 40,or does it stay the same?

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Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Stays the same (for 600AH).

Thank you Oldspark!

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Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

And I think you know about isolating them if unused for a while to prevent one discharging the other - specially if different types or ages or capacity or history.
When being charged from a car alternator they can be paralleled, and of course as needed for extra discharge capacity.
And to preserve "matched" batteries when discharging in parallel, co-house them with equal paralleling wires taking and +12V from one & GND from the other.

Well I did not know,I am thankfull for the advice.

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Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Good day Old Spark! Its been awhile.I have a question.on some batteries it gives the A/H and also a higher AMP total as 400A on the same battery.eg.45 A/H 400A.I understand how A/H works but the higher amprage I don't understand,can you please explain to me how this works.

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Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.

Sorry,this is what I got on mine,small battery that I'm using just for emergencies.

ClassA
Cn 45 A/H
Is 240A

What does the 240A means?

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Do it once,do it right - This means no short cuts. You never get paid twice for having to do the job twice because it wasn't done right the first time.