David VanHorn wrote:
> I would terminate high rate (or not start high rate) on one of several
> conditions: (1C charge assumed)
> T < 0C
> T>40C
 > dT > 2 degreesC/min UNLESS the cells are below room temperature.

I don't have a temperature sensor yet. It's on the drawing board though, ju=
st =

as soon as I get my mitts on a few LM35 temperature sensors.

> dV =3D 0 for 30S
> dV negative, with a 10 min lockout

A 10min lockout? What, you ignore the dV for the first ten minutes of the =

charge cycle?
I guess the negative dV is the delta from the peak voltage, i.e. Vpeak - Vn=
ow.

> Pack voltage exceeding 1.5V/Cell

Got that (or something close to it anyway). If Vcell > 1.7V then the charge =

algorithm fails with an "EOVERVOLT" error (maximum safe voltage exceeded).

> I measure at the end of short pauses that happen once a second.

Seems everyone does that. One second charge, 4ms rest, 5ms discharge, 4ms =

rest, 16ms acquisition time (16 samples at 1ms intervals, averaged out to g=
et =

rid of any noise).

The plan so far is to have a PIC16F88 running as a charge manager (the "PMU=
", =

power management unit), which runs the charge algorithms and reports back t=
o =

the second PIC. The second PIC will probably be an F628 or another F88, and =

will be responsible for dealing with the user-interface aspect of things.

It really all boils down to the fact that I'd rather have two PICs working =

together than try and implement the UI code and the charging / PWM / etc. c=
ode =

on one chip. PICs aren't exactly expensive (16F88s seem to run about =A31.5=
0 =

each), so using two of them isn't really a big deal.

> And I think you need to be even more careful if you're charging a battery
>> rather than individual cells - one
>> cell's +dV may mask another's -dV !
> =

> =

> Indeed they do.  Very good idea not to make up packs from cells with
> dis-similar histories

I'm using Kodak 1600mAh AAs and Energizer 2500mAh AAs - I've got three sets=
 of =

four of the Kodaks (plus a set of three), and one set of four of the =

Energizers. Note that these are loose AAs - I wanted them to use in my Game=
boy =

(don't deny and old man his few pleasures in life) and my digital camera =

(which consumes Duracells at a stupid rate).

In its absolute simplest form, this whole project is one giant example of N=
IH =

(Not Invented Here). But it's a fun example of NIH :)

-- =

Phil.                         | Kitsune: Acorn RiscPC SA202 64M+6G ViewFind=
er
philpem@dsl.pipex.com         | Cheetah: Athlon64 3200+ A8VDeluxeV2 512M+10=
0G
http://www.philpem.me.uk/     | Tiger: Toshiba SatPro4600 Celeron700 256M+4=
0G
-- =

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