Sennheiser IS 150 Instructions For Use Manual page 21

Rechargeable accuplugs have a „charging cycle"
Depending on how long your receiver has been in use, you must also recharge
the BA 151 accuplug for a certain time. A simple rule of thumb will help you to
decide what time is necessary:
Example:
1 hour listening
3 hours recharging
Operation with a second accuplug
By using a second accuplug, you can increase the listening time with your receiver.
The second accuplug is always inserted in the charging compartment
transmitter to ensure that it is ready and fully charged when it is needed.
If you use your system with only one accuplug, you must stop after
about five hours and recharge the accuplug for about 15 hours in the
charging compartment
Listen
2
With a second accuplug, you can listen for more than twice the time. Simply
place the discharged first accuplug back into the charging compartment. After the
(partial) recharge, there is an additional (partial) amount of power available:
2
Listen
1
2
Operating time x 3 = recharging time
2 hours listening
6 hours recharging
of the transmitter.
Recharge
4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 ...
Listen
Recharge Listen
4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 ...
3 hours listening
9 hours recharging
of the
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