simple precharging circuit will this work?

[dougy83]

discovered something about this circuit that seems wierd and I dun know the cause at about 130 mA the circuit clamps down so to speak the lights all turn on and that's that no more indication however the 130mA are freely flowing I dun know if the termination would work after that point . I tried with and without filter caps.

If the light is on, there should be no current flowing; are you sure all your transistors are connected properly? Perhaps you could just settle for charging them at 100mA?

I dunno happily working at 100mA though, although each circuit on the same Iset and Vset have some tolerances +/- 0.05V trigger and +/- 4 mA in current flow. I figure it's due to tolerances in the resistors used.
terramir

Those tolerances are very good (better than I expected).

 

[terramir]

If the light is on, there should be no current flowing; are you sure all your transistors are connected properly? Perhaps you could just settle for charging them at 100mA?

Yeah I can settle for 100mA but I'm trying to figure out the cause I'll be adding some wires between the power rails and the terminals to see if the voltage drop is the cause I mean 1.3A through 24 gauge wire is bound to frak with the voltage which in turn is probably fraking with the other stuff

Those tolerances are very good (better than I expected).

Yeah well I have like alot of resistors and the ones I didn't have I bought more than I needed I tried to keep the things as close as possible by measuring the resistors and matching closely. 8 % total variance in current and a 2-3% variance in termination voltage is bound to be expected. The catch is with so many cells to charge and the full chargers comming along nicely I will have to build another bank, which means more tolerances thrown into the mix. well next month a trip to allelectronics for some lm324's is in my future.
terramir

 

[terramir]

Had this question before But I'd like to ask it again
Would the KA3403D work in this circuit or would I have to modify it? If I can get them unsoldered I would like to try to use them cause it would mean more prechargers sooner. already the precharger cannot keep up with the main charger (8 working chargers ATM more to come)banks demand for cells.
Also another specific question R5 the 1.8meg resistor what function does it exactly have I was wondering what would happen altering the value to let's say 2.2meg or 1 meg for that matter. Just wondering because I got like 50 or 100 of those values and I'm right now scrambling for parts to make this go faster
terramir

 

[dougy83]

Should do the trick. Check that the pinout is the same (it probably will be)