Multiple mosfet control for a variable load tester

I have begun a project of building a load tester to test large lipo battery to determine there true ratings since most of them are beyond inflated. so I began to put together a large bank of 100 watt resistors and my i was planing on using a few mosfets to control the current to them. I decided to go with 8 IRLZ44PBF N-channel mosfets giving me up to 400 amps of head room. they were 5v gate so i was planing on using a arduino to control them. i knew i was going to need more current than 1 channel could supply so i used all of them and wired them into one larger wire. I tested at first with just 4 and a smaller load only about 20 amps i had no issue regulating the draw. so i finished building the rest got all 8 hooked up and a full 4000 watt load and with even the output on 2 out of 255(.03v out put to the gate) its pulling way to may amps causing huge sparks on connection and the fets are even building some noticeable heat at such a low gate voltage. I’m looking for any way to make the control a little more precise. i’ve linked my program( its bad ik this is my first time really working with anything like this) and a video showing the problem . https://youtu.be/mQJF8tECRd4

allpwmoutputs.ino (1.28 KB)

Hi,
Welcome to the forum.

I have begun a project of building a load tester to test large lipo battery to determine there true ratings since most of them are beyond inflated.
So I began to put together a large bank of 100 watt resistors and my i was planing on using a few mosfets to control the current to them.
I decided to go with 8 IRLZ44PBF N-channel mosfets giving me up to 400 amps of head room. they were 5v gate so i was planing on using a arduino to control them.
i knew i was going to need more current than 1 channel could supply so i used all of them and wired them into one larger wire.
I tested at first with just 4 and a smaller load only about 20 amps i had no issue regulating the draw. so i finished building the rest
got all 8 hooked up and a full 4000 watt load and with even the output on 2 out of 255(.03v out put to the gate) its pulling way to may amps causing huge sparks on connection and the fets are even building some noticeable heat at such a low gate voltage.
I'm looking for any way to make the control a little more precise. i've linked my program( its bad ik this is my first time really working with anything like this) and a video showing the problem .
https://youtu.be/mQJF8tECRd4

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

What model Arduino are you using?

Thanks.. Tom.. :slight_smile: