> Hey, what do you guys think of this project?
>
> http://www.stefanv.com/electronics/battman2.html
>
> I've been looking to make or buy a computer controlled battery
> charger/discharger with voltage/temperature monitoring.


Schematic

       http://www.stefanv.com/rcstuff/battman2/schematic.gif

Looks bearable.
4040 driven DAC for ADC is archaic but makes use of parallel port access ea=
sy.
Current setting is also primitive and biased towards parallel port use.
Use with a USB to parallel port converter would usually be required
and may work OK in many cases.

Saving grace is that this can (must) be software driven by the PC and
the software can be extremely accommodating.

I haven't looked at their software but it sounds as if they have at
least some idea of that they are doing.

This could be easily accomplished with a USB to PIC connection and
parallel port emulation may allow existing software to be used oir
they may allow access to the interface / BIOs to allow kluging/APIs
whatever.

This is only single channel and while it could be N channel the
software and port arrangements probably make that messy or hard or
worse.

Understanding the basics of this circuit would allow you to easily
implement a multichannel version that was at least as good with an eg
single USB connected controller.

Using even slow software PWM would allow current setting for charge
and discharge at much higher resolution and flexibility.
Use of processor ADC allows 4040 method to be banished.

I have one of the MAHA chargers mentioned and, while it has
limitations that it shouldn't have it is utterly marvellous and very
useful. The Lacrosse BC9009 / BC900 looks capable and is chaper than
I've seen the MAHA. I'd say that for serious use, if the laCrosse or
MAHA met your needs then they would be value enough for money to buy.
If you have specialist needs then rolling your own would gbe "not too
hard" tm and could be very worthwhile.



          Russell McMahon
--=20
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