I have done this type of project using Benchmarq chips in the past. The
14000 is a good choice for this type of project. By tracking power in vs
power out along with time and temperature you can build a type of gas gauge
for the batteries. A problem comes from the fact there are losses in
efficiency and a memory effect can also limit capacity such that a battery
conditioning cycle should be done every so often.


At 01:37 PM 4/28/98 +0200, you wrote:
>Hi,
>
>I am going to build a system based on rechargable batteries (NiCd). At any
>time, I need to know for how many minutes can this system run without
>charging. The batteries will under normal condition be charged for 2.5
>minutes and discharged for 2.5 minutes. This will go on for weeks, so I
>need a reliable way to tell when it's time to change batteries. And, I need
>to know before the batteries fails.
>
>-To keep On Topic, This will off course be done by a PIC...
>
>Has anybody got any experience with this kind of problems??
>
>Regards,
>Haavard
>------------------------------------------------
>HŒvard T¿rring
>ht@neo.no    xplisit@neo.no    simplisit@neo.no
>Norsk Elektro Optikk A/S       Tel: +47 67974700
>PoBox 384                      Fax: +47 67974900
>1471 SkŒrer                    http://www.neo.no	
>Norway
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@ieee.org
http://www.ultranet.com/~nr