Precision Measurement Engineering, Inc.
(760) 727-0300
www.pme.com
9
If the marine growth remains, then use Q-tips to gently wipe the sensing foil after it has been
softened by soaking in vinegar or perhaps diluted HCl. After cleaning the sensing foil, then it
should be rinsed well in clean tap water before storing or reuse. Do not use other organic
solvents such as acetone, chloroform, and toluene since these and others will damage the
sensing foil.
The sensing foil can also be cleaned using a 3% H2O2 solution or rinsing it with ethanol.
The white pressure housing and black end cap can be gently scrubbed.
AA Alkaline Battery Life
– Alkaline batteries will give somewhat less performance than
lithium, especially at low temperatures. Alkaline batteries are superior to lithium in one way:
you can determine how much battery life remains by measuring the battery terminal voltage.
For short deployments of a month or two, then alkaline batteries will provide adequate
performance. For longer deployments, or for deployments in cold environments, then
substitute lithium batteries.
AA Lithium Battery Life
– The miniDOT Logger consumes battery power mostly from the
measurement of dissolved oxygen, but also slightly from simply keeping track of time, writing
files, sleeping, and other activities. The following table shows the approximate endurance of
the miniDOT Logger when powered by the Energizer L91 AA lithium / ferrous disulfide
batteries:
SAMPLE INTERVAL
(minutes)
Main AA Battery Life
(months)
Number of Samples
1
12
500K
10
>12
>52,000
60
>12
>8,000
Keep a general record of the miniDOT Logger’s number of samples. It is not possible to
accurately tell the charge state of a lithium battery by measuring its terminal voltage. If you
have a general idea of the number of samples already obtained on a battery, then you can
make a guess as to how many more samples remain.
The numbers in the table above are, at the time of this writing, based upon extrapolations of
testing of 500K samples acquired at a 5-second interval. The 1-year performance at 1
minute is very likely. Performance at longer sample intervals will be much longer, but how
long is difficult to predict. In any event, these AA batteries are easily available and relatively
inexpensive compared to the cost of the miniDOT Logger. PME suggests you replace the
batteries often, especially before any long (months) measurement deployments.
Monitor battery voltage in the miniDOTControl program. You cannot tell from terminal
voltage of a lithium battery how long the battery will last, but you can tell if it will die soon.
