Pardon me for asking what may be a simple question. If you discharge the 7.5 V nicads into 47R (160mA) for 10 seconds what would you expect to see in a good / marginal / bad battery for voltage? Does the manufacturers data indicate these values? If I had a 12 volt lead-acid battery at 1AH and I discharged it at X mA would I discharge a 10 AH 12 V lead acid cell at 10X for the same indication of battery condition. Could I use the PWM O/P (set at 10% or 100%) of a PIC to control the load via a FET for both of these tests or would I require two separate loads? Thanks in advance for any assistance. Guy ---------- > From: Tjaart van der Walt > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: Batteries > Date: Tuesday, November 25, 1997 9:45 PM > > Andrew Mayo wrote: > > > > In order to reliably determine battery life, you really need to be able > > to briefly switch a load across the battery which draws a predetermined > > current and then measure the battery voltage. Battery manufacturers can > > supply voltage/time curves for a given load, if you ask. > > This is exactly what we do to determine a 6 cell NiCd pack's state. I > discharge it over a 47E resistor for 10s and measure the voltage under > load. > > A few people have asked about good batteries to use lately. A very nice > battery (but a bit expensive) is the Hawker (previously Gates) Cyclon > 2V lead acid cells. They combine all the nice features of lead acids > and NiCds. > > -- > Friendly Regards > > Tjaart van der Walt > mailto:tjaart@wasp.co.za > _____________________________________________________________ > | WASP International http://www.wasp.co.za/~tjaart/index.html | > | R&D Engineer : GSM peripheral services development | > | Vehicle tracking | Telemetry systems | GSM data transfer | > | Voice : +27-(0)11-622-8686 | Fax : +27-(0)11-622-8973 | > | WGS-84 : 26010.52'S 28006.19'E | > |_____________________________________________________________|