Please explain so I have the rite info.
Batteries are not rated at 1A. His whole premise was incorrect based on a typographical error on some Wal*Mart batteries.
Deep cycle marine batteries are rated in Ah capacity at a 20 hour rating. They may also have a 10 hour or 1 hour or 100hour rating but the rating on the sticker is almost always the 20 hour rate.
The 20 hour rate is:
Ah capacity / 20 = XX
A 100Ah battery is only a 100Ah battery with a 5A load at 77F when continuously discharged to 10.5V at 5A.
A 200Ah battery is only a 200Ah battery with a 10A load at 77F when continuously discharged to 10.5V at 10A.
A 375Ah battery (see below) is only a 375Ah battery with a 18.75A load at 77F when continuously discharged to 10.5V at 18.75A.
As can clearly be seen the Ah rating is at 20 hours. Any discharge rate above the 20 hour rate of 18.75A shrinks the battery capacity. Any load below the 20 hour rate can increase the bank capacity.
Beyond that every lead acid battery maker, other than Firefly, recommend a maximum depth of discharge, in a cycling application of 50%.
Due to declining charge acceptance, once at absorption voltage, it is pretty rare that you would be able to charge back above 80-85% SOC, on a sailboat when out cruising, thus your real usable capacity is just 30-35% of the actual Ah rating.
This means the actual
usable capacity, from a 200Ah battery bank, is 60-70Ah's when out cruising or 100Ah when fresh off 100% charge from the shore charger. Course this is only if the discharge rate remains below 10A and the batteries are actually healthy enough to deliver their capacity rating. If you apply a 30A load you will get considerably less
usable capacity than you would below 10A...
