gob
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Re:Battery testing questions... - 2007/06/19 03:59
In the testing methodology, the cells are cycled until they show no further improvement.
Some rechargeable batteries need only two cycles, and some need up to 5 or six cycles. This is when we measure the capacity.
If we had the resources some of these larger companies had, we would be lucky enough to have a sophisticated fully automated test system. When we started testing the rechargeable batteries, we realized that we had to pick one method and stick to it.
In our case, the fixed load test was the most predictable and affordable.
When we talk about the labelled capacity, we use this as our reference because this is the consumers reference point. This is what the consumer sees and assumes the capacity is. This is also what the rechargeable battery manufacturers are marketing.
When we publish the capacity, we use the 10 Ohm fixed load test.
When we calculate the results from the DAQ output file, we actually have all the data like Amp minutes, Watt minutes, etc ....
But that is a whole wack of data to manage.
For the general public, the consumer, we want to keep the information understandable ( for RBR, we want to keep it manageable )
On the Topic of Rechargeable Battery Manufacturers and Bad Cells.
We received and we will be receiving more samples from manufacturers. In the future, we have asked for larger sample quantities to give us a better view.
As for the other rechargeable batteries, we simply went online and bought some just like any other consumer. Since our budget is not unlimited, we got what we ordered, just like a consumer. So in reality, it is a fair comparison.
We have had a few manufacturers mention that they will send us more samples due to "odd" results from early batches. If a manufacturer wants to send us additional samples for re-test, they can certainly make arrangements with us.
The cells that show lower than expected capacity, even below 80% ( which some use as the life cycle barrier ) are on the list because this is what we received.
If a non-suspecting consumer bought these, how would they know what they got? How would they even know that they should return them? If they did, would they get more of the same? Would they get their money back?
It's interesting that certain products, for which we've tested various capacities, show similar lower than expected results ( even at our gentle 10 Ohm test ). It is not coincidence.
The LaCrosse BC900 and the Maha MH-C9000 confirm that we are not way off track with our results.
Many of these manufacturers are unreachable. How many times have I tried to get someone at Accupower from their information online.
Rechargeable Battery Life Cycle
What is the measure of the "number of charge cycles"? 1000 cycles like you see on all those packages, not likely.
Time, give us more time in a day. We would love to do some head to head life cycle tests.
More Battery Testing Methods
Yes, testing in real life applications is a better guage. We started this with the AAA rechargeable batteries and the MP3 test which is a slow discharge test.
We designed an LED Flashlight test setup using a black box and a solar cell / collector. The LED Flashlight test would use a high drain LED Flashlight we bought for the AA and AAA batteries that are supposed to last approximately 3-4hrs.
I think using real devices in a slow drain and high drain application is useful as you say.
Right now, there does not seem to be great interest in such tests ( let us know if there is).
Fron Feb to May, we've concentrated on getting our final website fully developed.
Maybe we'll revisit these before the end of the summer.
gb
Post edited by: admin, at: 2007/07/12 20:46
Post edited by: admin, at: 2007/08/30 22:00
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