Friday, July 25, 2008
Questions & Answers from the Weekly Tips section at all-battery.com...
The following, within quotes, is one of the Questions & Answers from the Weekly Tips section at all-battery.com...
"I am confused about the 28 volt airplane systems. Do they use 28 volt batteries?
Cars and trucks and other ground-based equipment traditionally use the "2 volt per cell" terminology. For example a 6 cell battery is a 12 volt battery even though the open circuit voltage is 12.9 volts and the charging voltage can be above 14 volts. This is because the "average" voltage as a lead acid battery is discharging is about 2 volts per cell.
Aircraft have used a different standard. They typically quote the alternator voltage rather than the battery voltage. This make sense because (even for ground equipment) most of the time the system is running at the alternator voltage, the battery itself never gets discharged very much. The alternator voltage is nominally 13.8 volts for a "6 cell" system and 27.8 volts for a "12 cell" volt system. This is typically rounded to 14V and 28V.
Therefore a 28 volt aircraft electrical bus will have a 24 volt lead acid battery in it.
So the answer is "No, 28 volt aircraft use 24 volt batteries.""
~~
"I am confused about the 28 volt airplane systems. Do they use 28 volt batteries?
Cars and trucks and other ground-based equipment traditionally use the "2 volt per cell" terminology. For example a 6 cell battery is a 12 volt battery even though the open circuit voltage is 12.9 volts and the charging voltage can be above 14 volts. This is because the "average" voltage as a lead acid battery is discharging is about 2 volts per cell.
Aircraft have used a different standard. They typically quote the alternator voltage rather than the battery voltage. This make sense because (even for ground equipment) most of the time the system is running at the alternator voltage, the battery itself never gets discharged very much. The alternator voltage is nominally 13.8 volts for a "6 cell" system and 27.8 volts for a "12 cell" volt system. This is typically rounded to 14V and 28V.
Therefore a 28 volt aircraft electrical bus will have a 24 volt lead acid battery in it.
So the answer is "No, 28 volt aircraft use 24 volt batteries.""
~~
Subscribe to Posts [Atom]
