FF
Guru
- Joined
- Oct 12, 2007
- Messages
- 22,552
Some folks are under the illusion that a 100A alternator will stuff 100A into a 200A batt set in an hour and they are done.
This months Home Power , avilable on line has a great simple article Battery Instalation anf Maint starting on page 74.
Most interesting was the Surette formula for the Absorbtion phase ,
the one AFTER* the Bulk Charge* that brings the batts back to 80% SOC .
Absorb time =(0.42 x batt 20 hour capacity ) Divided by charge current
So an 800A bank with a 75A charge
(.42 x 800ah) divided by 75 = 4.5 hours of Absorb time!!
*
Sure 800 ah would be a large boat setup , but run the numbers for your house set .
My guess is almost everyone that does not top off with solar is constantly undercharging .with short set life and lousey performance the result.
This constant undercharging (never getting to 100% full charge) would be easy to see with a SOC meter.
For most cruisers the daily long charge time is simply unacceptable , the solution is to operate 50% to 80%SOC* , just bulk charging .
This will degrade the set so a larger* bank and more frequent replacement is the norm.
The price of quiet.
*
*
This months Home Power , avilable on line has a great simple article Battery Instalation anf Maint starting on page 74.
Most interesting was the Surette formula for the Absorbtion phase ,
the one AFTER* the Bulk Charge* that brings the batts back to 80% SOC .
Absorb time =(0.42 x batt 20 hour capacity ) Divided by charge current
So an 800A bank with a 75A charge
(.42 x 800ah) divided by 75 = 4.5 hours of Absorb time!!
*
Sure 800 ah would be a large boat setup , but run the numbers for your house set .
My guess is almost everyone that does not top off with solar is constantly undercharging .with short set life and lousey performance the result.
This constant undercharging (never getting to 100% full charge) would be easy to see with a SOC meter.
For most cruisers the daily long charge time is simply unacceptable , the solution is to operate 50% to 80%SOC* , just bulk charging .
This will degrade the set so a larger* bank and more frequent replacement is the norm.
The price of quiet.
*
*