Lasted edited by Andrew Munsey, updated on June 15, 2016 at 1:18 am.
'In Reference to Bettery Involvement in John Bedini's "OS:Bedini SG"'
Sent: Tuesday, October 26, 2004 2:05 PM
Subject: [Bedini_SG] Most Ah ratings are INCORRECT
Most lead-acid batteries are MISlabeled with a higher Ah rating than
what they really usefully contain.
UNLESS you get a true deep-cycle battery, you're not getting what you
Gel-cells are usually WAY overrated on useful Ah. The rating on the
battery probably also includes the BTU's you'd get if you were to set
it on fire after you powered your load with it.
For any "regular" lead-acid battery with a CCA rating, just divide
that CCA number by 20 and you'll have it's true Ah capacity.
But, STARTING BATTERIES are not deep-cycle worthy. So, you can only
have the first 20% of that CCA/20 figure without damaging that
battery. As an example, a 600 CCA battery has 600/20 = 30Ah. Then take
that 30Ah/5 = 6Ah of usable charge without damaging the battery.
Short answer is, DON'T bother with starting batteries, except for
Just buy deep-cycle batteries and be done with it for your storage
In any case....
You don't need a lab to know approximately what you can get from a
battery, just a CONSTANT CURRENT load.
Electrical charge is defined in measured quantities of electron charge
"Charge" in a battery is defined as Ampere-hours.
ONE "ampere" is defined as ONE COULOMB PER SECOND of "flow".
So, you COULD write this as (Coulombs per second)-hours.
"Ah" is much simpler.
Forget the "voltage" except as a starting and finishing point
measurement. The batteries are rated in Ah NOT Watt-hours. Ah only
considers the COULOMB content of the battery, not the voltage at which
it is released.
1. Start by using 80% of your Ah rating as your REAL USEFUL CHARGE
CAPACITY. This means a 100ah battery should be considered an 80Ah
battery. Got it? Good.
2. Divide that 80% number by 20. So it's 80Ah/20 = 4 amperes. You
can draw a steady 4 amperes for 20 hours from a 100Ah battery without
3. Apply the 4amp load to the battery for 20 hours. Then remove the
load and see where the battery voltage pops up to.
If it's below 12v, then the battery's labeled rating is wrong.
Recharge the battery with a charger that can get it's voltage up over
12.6v within a couple of hours. If it takes longer than that to get
over 12.6v, the battery is already beginning to sulfate.
Directory:Bedini SG:Battery Characteristics - listing as part of the Bedini SG project.
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