Richard Sherrow (BATF) left Washington DC on 27 September 1986 for Lomé (Capital of Togo) at the request of the U.S. Department of State. Sherrow was accompanied by Edward Owen (BATF) and James Casey (Dept. of State). Of course, the readers of this blog have learned that a fourth person joined them. His identity is unknown, but his/her employer was the CIA.
In his FD302, Sherrow stated that:
Batteries were in place on both timers. The connecting wires had been soldered to the posts. (…) Both batteries were considerably drained.
Now according to the CIA report (see page 9), the battery (a DURACELL 6V 7K67) was rated 500 mAH. And the current consumption of the device while counting (@5.5V) is about 0.4 mA.
The FBI report signed by Thomas Thurman also mentions 0.4 mA but I suspect that the author merely copied the CIA report.
Therefore, according to the CIA report, the battery should last up to about 1250 hours, that is more than fifty days.
Thus, I fail to understand why the batteries were exhausted considering that BATF Richard Sherrow allegedly recovered these timers just a few days after the attempted coup.