The meter itself is suspect. Anyway look at it this way...
The existing battery cannot do the job
Regardless never pair a brand new battery with an old battery.
Time to get 200 A/H worth of batteries then start playing with the meter. A correct 50% discharge level for a 80 amp hour battery 40. ¿Si?
40 X 12.2 volts the span average I use is .488 kWh consumed. 1 hour 90 days, the consumption is .488 kWh
You may or may not want to trade kWh potential for overall lifespan + ease of deep cycle maintenance). Golf car GC220 batteries fall under the latter category.
As battery specs get more crooked and deceptive, plates get thinner and paste less pure. Look for amp hour ratings and weight (amp hours per pound). The fewer the amp hours the thicker the plates = when comparing equal weights.
After your battery selection is made only THEN, start calculating draws and recharges. Note that batteries "cure" after ten cycles or so. You can help by performing a "TOP CHARGE right out of the box.
A DEcrease of discharge from 50% to 60% remaining capacity is something to consider. This is why I recommended 2 group 27 good quality batteries like Trojan or Deka.
Watt seconds, minutes, or hours is MOST useful in COMPARATIVE battery studies. Comparing a battery to similar ones off a production line - comparing current energy factors to the battery when new.
Little value in hitching a fresh horse to a 2 horse wagon when the other horse has a broken leg.
But in any event replace with 2 new batteries. Is this recommendation redundant enough?
