> I'm using the LIR2032 battery (Nominal C = 35mAh and standard charging
> method = CC 17mA (0.5C)). Thus the PROG resistor i'm using is 60K4 (aprox.
> 16mA).

> I can't just plug a battery and check the current value. It will be tested
> in the production
> and must be a fast method. The people that will make it, must just verify
if
> there is a known current value. As the current depends on the battery
> voltage, i can't use it.

OK. You just provided (probably) enough information to make sense of your
questions.
If you had provided all relevant (and some irrelevant ;-) ) information at
 the start we'd be home by now.

Apparently the issue is that you wish to production test chargers to ensure
that  there are no gross PCB faults and to ensure that the circuit performs
major tasks correctly.

This sounds 'not too hard' [tm] BUT you really need a custom battery
emulator that speeds up the process.
You also need a good understanding of what the charger IC does at each stage
and why.

It seems likely that  a capacitor possibly with a resistor network, would
test the low battery and constant current parts of the cycle.

Provide a capacitor of sufficient capacitance that it will charge to full
voltage at 1C in an acceptable time. YOU define what the acceptable time is.
Let's suppose it is 10 seconds.

Precharge the cap to slightly under the low voltage trickle up voltage.
Connect the charger. The cap will be charged at 0.1C until it reaches the
low voltage thresh-hold, then jump to 1C and charge until Vmax is reached.
It will now go into constant voltage mode.

If a single cap is used as above it will immediately stop accepting current
and the charge cycle will terminate. To emulate the constant voltage,
declining current "tail" you could try adding a second smaller cap in series
with a resistor with time constant that it is still not fully charged when
the main cap reaches Vmax. It will now accept current via the resistor and
current will fall off exponentially. by suitable sizing of the two caps and
the R a suitable length 'tail" will be obtainable.

Problems may occur if the IC is "too smart" and tries to put finite delays
into the system between phases. In such a  case you either need a better
battery emulator OR it's not doable due to IC constraints.

Note that the 5 hour fully charged period is a function of at least 2
factors. The LiPo cell will slowly reduce current when held at vmax. The
charger IC will have some C/X value where it deems the current to be low
enough to show that charging is complete. These two interact.

Note that if you want maximum battery life you should set the current tail
cutoff  current as HIGH as possible. eg when current falls to say C/4 you
stop charge. Some use C/10 or C/20. The longer you run the more capacity you
get, but the gains are small and it severely affects battery life.

Note also that for best life you can reduce Vmax by about 0.1V below
manufacturer's maximum recommendation. this also takes something off gross
capacity (maybe 5%-10%) but increases cell lifetime substantially.

Precise results of the above life extension methods depend somewhat on
precise chemistry and manufacturer. Still quite a lot of arcane art in Lixxx
batteries.

Note that when you transition from CC to CV cell is in the 65%-80% charged
range and typically is about 1 hour into charging at C. In you case you get
the remaining 20%-35% over the next 4 hours.

THE optimum charge point for lifetime is at the CC/CV transition. If you
terminate charging there (say when current falls to 90% of CC) you get a
much longer battery life in exchange for reduced capacity.

Terminating lowest cutoff at a slightly higher voltage also helps.


          Russell McMahon
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