www.webx.dk Start page
MY little Radio Control page
Schulze ISL6-330d Modification 10A discharge

On this page you will find homemade modifications to perform on your ISL6-330d Schulze charger
To make it discharge 10A, fully automatic controlled as usual.

To make the ISL6-330 discharge 10A, I simply add an external current generator,
this current generator will suck 9.00A when enabled via optocoubled on/off signal from the ISL6-330
the charger it self will suck 1.00A max as usual.

After searching a few hr for a good stable ON/OFF signal inside the charger,
a signal that will go lo/hi when discharging, I gave up.. then I found the analog current setting system.
The discharge refference voltage is present at this location, the emitter of this SOT23 NPN
1000mV gives 1000mA at the internal TIP135 PNP power transistor.
Adding a litte opamp board using this sehematic:

now we have the automatic software generated on/off signal we need for the external current genertor.
The reson why I use an optocoupler to control the external current generator
is due to the fact that the charger and battery ground is NOT connected.

This current generator is simple and easy to make using a huge N-FET and one opamp,
note the on/off signal is made so I can use the current generator on other projects,
without the A-B signal connected, the generator will be ON !

Imagine the few minutes it took to splash all this together :-)

About the N-FET, 9A and 8V to 12 V is 72W to 108W, so using only one little TO-220 Fet will not work,
ok you can use TO220 fets, but use more and then divide the 3 source resistors into more, then you can get away cheaper
I have just used this crewl 150W fet, coz it was in the drawer.

Use a heatsink of extreme size, and add a fan to cool it when discharging, else.. you imigine..

I used a good old plug from a dead PC, it is easy to glue it to the bottom side of the charger
and easy to find a part that fits into it.

closing time.. a few hr later..
now I will have fun making a few curves.
Did I say why 10A is genious ? Then just x 10 to Amp and mAh readings on the display and PC program curves.


Here are 6 IRFBC30A fets connected in parallel, each source resistor is R47 Ohm,
so the total source resistanse is 78mOhm, this gives 705mVolt at 9.0Amp, and about 1 Watt wasted in each resistor,
the six 2k7 resistors are used to measure the avarage voltage over the sence resistors, maybe not really nesesary,
but I like to make it neat in this version 2.

First test, I had to charge a bit first

Note each gate has it's own resistor 680 Ohm, the trimmer is 220 Ohm, top resistor to +5 is 2k2, and bottom resistor is 270 Ohm
This makes the adjust range from 500 to 900mV, so the 700mV we need is almost in the center
The other part of the LM358 is used to control the fan on/off.

The discharge opto signal from the charger is easy to access at this plug.

The 9A extra discharger is simply connected in parallel with the ISL6-330D

After a few minutes without a fan the heatsink got too hot, so I added this nice fan tunnel

when it charges the fan goes really slow, when discharging it run at full speed.

The schematic was too big to have in one piece, sorry I have no time to re-draw it.


All modifications you make is done at your own risk !
you will not have any warranty on your charger after performing any of this mods.
Please dont violate any copyright laws.