BATTERY SHOP PAGE
2 - Battery Testing
JFM Engineering operates an FAA certified battery shop providing expert care for
your batteries (FAA YJFR824L)
Purpose of Battery Testing:
Types of Tests:
Our Battery Test Operation:
Note: Description of tests refer primarily to Nickel-Cadmium batteries. Additional comments are provided for Lead-Acid batteries.
Top charge:
Top charge is the simplest
type of service for all types of batteries. Batteries are "topped off" before
being put on the aircraft to compensate for self-discharge while in storage. Top
charge is also used to determine the proper electrolyte level. Water is normally
lost during usage and it is also lost due to evaporation. When the battery
reaches full charge, the electrolyte is at its maximum level; distilled water is
added as required.
The top charge process is also used to measure cell voltages,
to determine that each cell reaches the proper charge voltage and to check if
any cells exhibit a temperature rise and/or drop in their voltage under constant
charge current (topping current).
Lead-Acid batteries are also top charged, and if of the
flooded type, the specific gravity and level of electrolyte is also tested and
adjusted as necessary. On sealed batteries, the specific gravity of the
electrolyte cannot be measured.
Capacity Test:
This is the most important
test, for it determines if the battery is fit to return to service. After
receiving a full charge, the battery is subjected for one hour to a typical
discharge current of 100% of its rating. If none of the cells drop below 1V, the
battery passes the capacity test. It is then recharged and returned to service.
If one or more of the cells drop below 1V (even if the battery as a unit does
not drop below 20V) the battery fails the capacity test.
What happens next depends on the individual condition of the
cells. If the cell voltages are reasonably similar (balanced), the battery is
recharged and re-tested for capacity. If the cells are heavily unbalanced, then,
the battery is subjected to a full discharge (deep cycle).
If after three tries, one or more cells fail to meet the
capacity test, they are replaced. If more than 20% of the cells need to be
replaced, it is recommended that either all the cells be replaced or that the
entire battery be replaced .
Lead-Acid batteries are similarly tested for capacity, but with
no individual cell readings (terminals for individual cells are not available).
Deep Cycle:
A battery where the cells are heavily unbalanced, either as received for
testing or after failing a capacity test, must be fully discharged. This allows
all cells to start from zero in the subsequent recharge, thus restoring the
balance in the cell voltages.
Lead-Acid batteries are never discharged to zero during testing
Overhaul:
Batteries
are not repairable, at least not with the same meaning that we apply to other
devices. The basic component of the battery is the cell (or cell block in a
Lead-Acid battery). If cells fail to perform, they are replaced. The same
is true for other parts such as temperature sensors,
connectors, links and fasteners.
A battery received for overhaul will get fully disassembled
and washed. Cells will be inspected for leaks and burns.
Interconnecting hardware, (connectors, links, screws, nuts and washers),
are normally cleaned. If burned or corroded, they are replaced.
3 - Battery Testing Consulting
JFM Engineering can assist you with consulting support for the establishment of a Battery Testing Facility and with training in Battery Testing
4 - Articles on Battery Testing
Aircraft Battery Testing Definitions and Notes
Battery Testing
Guidelines
Importance of Water Leveling
Series
Testing of Nickel-Cadmium Batteries