>> > Sorry I haven't read all responses to this so this might have been
>> suggested but have you read the microchip
>> > document DS51596. This tells you on page nine how to make a battery
>> emulator. Which consists of a 1000uf 10v
>> > alu capacitor and 5ohm 2w resistor.You also need a diode and a 0-6v
>> variable supply.

>> > http://ww1.microchip.com/downloads/en/DeviceDoc/51596a.pdf

> Be aware that the 2W rating for the load resistor is rather optimistic. =
=A0With 6v from the supply and assuming a silicon diode, the resistor will =
be seeing ~5.4v across it and dissipating almost 6 Watts.

Also note that the manner of use of the simulator may not be as it appears
The charger is intended to supply 500 mA maximum.
At 4.2 V the 5R resistor passes 840 mA, so the charger cannot pull it
to full battery voltage by itself.
At 500 mA the IC will be limited to 2.5V and, as the preconditioning
voltage is 2.8V, if the external supply is not used the IC will not
pull the resistor to much above 0.25V (assuming C/10 trickle up
current).

So, the external supply provides "makeup" current and the battery
voltage is largely controlled by the external supply. Which is a good
feature, as long as what is happening is understood.

For Icharge =3D 5-- MA and Itrickle =3D 50 mA say, then an eg 1 Farad
supercap connected to the battery terminals, when below 2V8 would ramp
by about about 50 mV/second, and when above 2V8 by about 0.5V /
second. So if the cap was precharged to say 2V6 it would charge to 2V8
in 4 seconds and then to 4V2 in (4.2-2.8) / 0.5 =3D 2.8 more seconds. A
simple analog voltmetetr on the cap or an oscilloscope on
appropriately slow sweep would rapidly show if the system was working
as intended with no intervention other than turning it on.

For a smaller charging current adjust cap size to suit.
A second cap with a series R could then provide a declining CV "tail".

An almost fully automatic functional test in as many or as few seconds
as desired.

Doing the same with a processor controlled load would also be easy and
more flexible.


 R

-- =

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