Olympus BLM-1 LiIon battery test
The original Olympus BLM-1 LiIon
I tested the capacity of the original Olympus BLM-1 battery and of
cheaper alternatives and measured the following (all betteries had a
nominal capacity of 1500 mAh and were three months old):
These are the discharge curves (battery loaded with a 13.6 Ohm
- Original Olympus battery: 1299 mAh
- 3rd party battery 1: 1077
- 3rd party battery 2: 744
It is possible that the capacity is higher if you discharge the battery
over a period of five hours instead of three.
What does all this mean ?
- Well first of all, the original Olympus BLM-1 battery had the
largest capacity, 20% higher than the first 3rd party battery. The
second 3rd party BLM-1 battery must have been defective, because it had
only a capacity of 744 mAh.
- On the other hand, the original Olympus BLM-1 battery costs 70
Euro or more, while the 3rd party battery costs 4.2 Euro (= US $ 5.49)
in ebay - that's 17 times more ! There is no point purchasing the
original when the cheaper 3rd party alternative costs 1/17 of the
See below for an in-depth discussion
of the results and the test method.
After purchasing the Olympus 8080 in
July 2004 I faced the problem of getting a second battery without
paying the ridicolously high prices Olympus is charging for its BLM-1
battery (70 Euro or more in August 2004 in Germany). After hearing
positive reports I ordered two 3rd party BLM-1 batteries from an ebay
seller in Hong Kong. The cost per battery was US $5.49 per battery and
for the two
batteries I ordered I payed a total of US $17 including shipping. The
batteries arrived in 10 days. To get a more accurate idea of how long
the 3rd party batteries last
with respect to the original Olympus one, I recently ran a test.
Test configuration and procedure
Before the test each battery was discharged completely and then fully
recharged. The battery was then loaded with two 6.8 Ohm resistors -
was 13.8 Ohm. The drain current was therefore a bit over 0.5 Ampere on
average. This is a high current - on average a camera like the Olympus
8080 for instance drains around 0.2 Ampere.
With this load it took between 80 and 140 minutes to completely
discharge the batteries. Since I didn't have an A/D converter with a
computer interface, to measure the voltages over time I used
a standard digital multimeter and took automatically photos of it every
seconds using a camera control software:
Here the camera is connected to the computer with a USB cable and takes
shots of the multimeter every 60 seconds.
This is an example shot:
I have then entered manually the measurements into a table.
The capacity is obtained by adding all measured voltages and
divide that by 13.6 (the resistance) and divide by 60. That gives you
the capacity in Ampere-hours.
If you have a look again at the
discharge curves, you will note that the voltage is not constant, and
over a large period of time drops by about 10 mV per minute. Below 6.5
Volt the battery voltage collapses very rapidly (in less than 10
minutes) and the beginning of the steep drop region is at about 6.6 -
It also appears that the 3rd party BLM-1 batteries have a slightly
lower effective voltage than the Olympus original one. The difference
lies between 200 and 300 mV.
The lowest recorded voltage with a BLM-1 battery was 5.4 Volt. Below
this level the battery voltage drops to 0 in less than a minute.
© Alfred Molon 2004