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Old Jan 08, 2009, 07:56 AM
Al Offt is offline
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Boston, MA subburb
Joined Sep 2004
1,213 Posts
Paul,

I like the idea and if you can keep the cost around $60, I suspect they will sell. The primary advantage of your device over a whattmeter is that the user gains visibility into the condition of each cell rather than the whole pack.

A couple of suggestions:
Your symboloy is a bit confusing:
a. O: stands for open circuit voltage. 'Vo' might be better.
b. C: stands for loaded voltage, maybe Vl is better (i.e. C is recognized as capacity in the context of batteries)
c. resistance has the units of ohms so you might replace 'mR' with 'mohms'

In the final product, I suspect you will have to wire the cell balance plug to accept all cells and then cycle through all cells (either by user prompt or automatically), showing the condition of one cell at a time. Moving the cell balance plug is a pain.

In addition, not all cell adapter plugs are wired the same. Some are wired with increasing voltage on pins in a 'linear' fashion, others separate the most-positive tap from the others.And then, not all cell balance adaptor pins have the same spacing and physical size. Really a mess!

A really neat feature might be to have the device automatically choose the pins to use for each cell based on the voltage difference between pins so you don't need an adapter. Cell voltage for each chemistry (Lipos, A123s and NiCD/NiMH) is different so you'll need some way to determine what cell type is being used to make this method work.

If you don't have the device choose pin-pairs automatically, I suspect you will have to sell balance plug adapters (separate from the device to give the purchaser a choice) to make this device more attractive. After all, it will be ease of use that will make this device sell.

Good luck,
Alan
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Last edited by Al Offt; Jan 08, 2009 at 08:04 AM.
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