I found this website:
<http://www.mpoweruk.com/chargers.htm>
I don't know if you're going to find the spreadsheet you're looking for.
There are many methods of charging batteries. What you may need to do is
some experimentation.
You mention that the -dv method slightly overcharges cells, creating
heat. It was my impression that NiMH cells heated up as a result of
becoming fully charged.
My AA cells get pretty warm in the charger. There was an EV (the RAV4?)
that had to run the A/C when charging, to keep the huge NiMH cells at a
reasonable temp.
--
Martin K


Philip Pemberton wrote:

>Hi,
>   Has anyone here got a recorded charge profile from a NiMH battery? What I'm 
>after is - in effect - a spreadsheet with three columns:
>   - Time
>   - Voltage
>   - Current (optional)
>
>Does anyone have anything like this kicking around their HDD? The battery 
>manufacturers seem to be quite happy to give out pretty pictures of their 
>charge profiles, but don't seem to publish actual numbers.
>
>I want to play around with charge termination detection algorithms for my 
>(half-done) NiMH charger, and I don't have any test data to feed into my 
>detection algorithms. I figure while I'm waiting for the parts for the 
>discharger circuitry to turn up (a DAC, a voltage reference and a few 
>op-amps), I might as well get some of the software algorithms tested and 
>tweaked for use on a PIC.
>
>What's bugging me is that the manufacturers are saying one thing (wait for dV 
>to hit -5mV per cell) while all the books and websites I've been scanning 
>through are saying different things. One suggested "zero voltage delta" (wait 
>for dV to get close to zero) and another suggested "inflection point sensing". 
>The latter involved calculating the first or second-order derivative of dV/dt 
>and looking for the point where the derivative crosses zero. Surely that would 
>produce the same result as zero-delta sensing though?
>
>The main thing is that -dV is reputed to slightly overcharge the cells (which 
>produces heat, which is bad) and 0dV allegedly stops that. But if you get the 
>trip point wrong, you end up undercharging the cells, which is also bad.
>
>As far as preferences go, data for any cell manufacturer is fine, but Sanyo 
>(or anyone who rebrands Sanyo cells - Kodak, Energizer or Duracell) or another 
>name-brand (Uniross excepted) would be preferred. Same for cell count - given 
>the number of cells in a pack, I can get the per-cell voltage back pretty easily.
>
>Thanks.
>  
>



-- 
Martin Klingensmith
http://wwia.org/
http://nnytech.net/
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