Kevin,

 My suggestion would be to place a small value resistor (resistance) in
 series with the battery pack, and measure the voltage across it.  Then
 calculate the current through the resistor (resistance).  Since the
 current is the same in the components of a series circuit, that will
 give you the charging current.   Say you used a 1 ohm resistor.  And lets
 also say you measure 1 volt across that 1 ohm resistor.  Current then
 would be 1 Amp.  If you measured 40mV across the resistor, your current
 would be 40mA.  This will be pretty accurate even with the voltmeter (DMM)
 connected because the input impedance of the DMM is probably at least 1
 MEG and more like to be closer to 10 or 20 Megohms.  And 1 ohm in parallel
 with >1Megohm is still 1 ohm.   Anyway, it's worth a try.   Just make
 sure your resistor can handle the power to be dissipated.  ie 2 watts
 should handle any current up to about 2 amps.  I would try to find a 5
 watt resistor myself.

 Let us know how you make out.

                                                 Regards,

                                                   Jim








>>----- Original Message -----
>>> I built this circuit for a battery charger,
>>> charging, so far so good. If I set CCPR1L
>>> higher than 15 the charging current drops to zero.
>>> Any ideas why ? I thought I would be able to lower
>>> the current down to 150ma for a trickle charge.
>>
>>How are you measuring the charging current? I know my multimeter doesnt
>>like
>
>>measuring current unless its relatively stable- and settles on zero if
>>it can't make its mind up.
>
> Hi John,
> Maybe this IS my problem. I have my DMM inserted in
> the circuit to measure the charge. Maybe the DMM is
> not registering the current correctly. Any suggestions
> on ACCURATELY measuring the current ? I have a scope
> on the PWM and the FREQ and Duty cycle are correct.
> Thanks,
> Kevin
>
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