One thing would be is if the bat gets hot. If it gets too hot you can and will have an explosion.
If you want to use a volt metter alone instead of a amp meter just measure across R15 the 0.22ohm resistor. Use the old current/voltage/resistance formula to find for current.
I = E/R
I= Current in amps.
E= Voltage in volts.
R= Restance in omhs.
So it would be:
I = ?/.22 With ? as the voltage measured.
Its the same as the shunt in the meter you are using but wont affect the circuit with added resistance.
Since charging any batter is how much current vs time you apply I am leaning back to the circuity, AAA battries and timer have been picked to keep from blowing the battery, car etc up. IE the circuit IS the fuse!
Oh here is the spects on the Q4 transistor:
http://nte01.nteinc.com/nte/NTExRefS...9?OpenDocument
Click on PDF spects to see max values etc.
Warnning! Even though the spects are for a generic replacement, that little transistor absolute Max Ratings collector current is 1 amp constant and 2 amp peak! So the 750ma makes sense.
A good friend thats delt with more PS than I will ever know, passed some info on a company that has some special charging IC. Since people are hyping up their cars, may be worth looking for a better charging circuit to replace this one.
So for those with fresh battries but cant charge could be that either or both the Q4 and R15 got tosted.
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