This thread has been started for discussion related to Aussie based builders of DIY 150V 45A mppt controllers, development of which is discussed in an associated thread '... roll your own', so as to avoid clogging up the excellent and advanced discussion in that thread. This is to allow for amateur/novice level discussion of all matters associated with these controllers from theory to build practise. Most current builders are also, ambitiously, building Wiseguy Inverters. Constructive input is invited from expert and experienced builders.

Best of British Luck to you all.

my advice:

1 - obtain a DSO, new ones are reasonably priced and will go a long way in
both learning how to avoid blown up FETs and choosing an adequate choke
for both mppt and inverters.

2 - a bench power supply or two, such that 50V at 5A is possible. Ones that have current limiting is needed.

choke design is very much "use what you got" but test it to ensure it will work at the power levels required.

3 - make a choke tester. it will use the DSO. and the bench supply.
You will discover during testing of the chokes how much power is possible
before saturation. In fact, making the tester and using it will develop a large
part of the skills needed for all this.

4 - get a decent DVM and leads. make some long leads with alligator clips to suit
the meter. this frees up hands to get somewhere safe. Consider also a UNI-T clamp meter that does DC current. We need to calibrate the mppt..

hope this helps.

Dammmit I agree, but also didn't want to hear that! :-), as I and we are beginners. I have a Uni-T Clamp meter: that's a start. We need the power suppply for inverter commissioning, which only leaves the DSO & tester.

That being said, most of the chokes in my haul have already been tested on the other thread and are steel laminate, or we could just buy chokes with established performance parameters.

Am studying the former threads in detail and will make more notes about the tester and methods described there in detail, for now.

Question directed to Revlac re: Aurora chokes. I'm now regretting pulling one of my two 5 kW Aurora chokes apart after seeing one in use, untouched, in your build thread. Not to worry because I have two more 3.6 kW units OTW, there should plenty nuff components there. I can rewind the bare choke as well.

Did you ever test that choke to saturation?

Picc of my choke candidates posted again for reference. I'll proceed with the build without the DSO in the interim, having confidence in my choke parameters.

I didn't do a saturation test on the Aurora choke, didn't see the need for it as Poida and others tested and posted results of many chokes (not one of these that I am aware of) these were a little bit bigger cross section than the aerosharp cores and results should be marginally better.
I still have one Complete 5Kw Aurora choke and will check it with the LCR tester (if it still works)when I get time tonight or in a few days orso, I need to build another charge controller anyway.


Edit:
Ok found something I was looking for, The lab power supply I have is only 30v not relevant but it has a USB power supply to run the LCR meter to test the choke.
I have photo's but you will likely do your own later so here are the numbers, The choke as is tested 517uH, now with the loop at the bottom cut One coil measures 157uH then join the 2 in parallel (as in the photo take not of which winding's are the inner layer and outer layer) I get 145.9uH
You may wind your own but this is an easy start for a first build IMO.
Edited 2026-05-22 22:22 by Revlac

Footnote added 2026-05-23 18:05 by Revlac
I used a LC200A tester, old version without the case.

Again a couple of questions:

- what wattage ratings are specified for the resistors?
- What are the hole spacings and max diameters for the capacitors, excepting the large 470 uF capacitors on the main board (10mm/35mm)? I assume these can be obtained from the PCB layouts if not readily available.

  Quote  

1/2 watt metal film is the same size as normal 1/4 watt

Capacitor typical lead spacing of 3.5mm 8mm diameter

If not sure sometimes you can see typical size components on old Grid Tie Inverter's for reference
Edited 2026-05-27 18:26 by Revlac

Years ago Poida put up a circuit to test a choke where it used a diode, a cap and a fet to pulse from an nano where a current sensor was put on the add to the scope picture.

Now I don't want to go off topic but my inverter has just gone past 80 Kw Hours and everything in my shed just works like using my mig @110 amps did break the 16 amp circuit breaker so a 25 amp one needs to go in.

As I did have both boards here I just had to try the first one that just works now I am on 24 volts and this MadBoard just works.

Now I did get a price on a 48 volt 600AH forklift battery where 5.5K aint a bad price so that is on my price list so I can power my shearing shed with this chinese Tip Top board that cost me $300.

So plenty of options mate


Regards Bryan

The electrolytic capacitors on the MPPT power board are 35mm diameter, solder pins are "snap in", the snap in mounting hole centres are 10mm on the PCB.
C1, C2 are 3.5mm
All the ceramics are monolithic or film and are 0.2" or 5.08mm
All resistors are 0.4" or 10.16mm

The resistors are all 250 - 500mW, but R9 & R10 should be 600mW - 1W but the hole sizes are only ~0.9mm so some resistors could be tight. I think for R9 & R10, I used 2 x 22R 400mW in parallel ie bend the pins as if either could insert into the board & solder one in parallel to the other just where the legs exit the body so you insert the piggy backed resistors as 1 part. From memory the resistors ran hot - they were an attempt to reduce emi, if they run too hot try reducing C18 & C19 to 470p but with at least a 63 or 100V rating.

my choke tester:

A simple thing to do, that will be a good exercise for the skills
you need to build upon if you want to make your own inverter.

basic operating idea is to have a variable length pulse (5V)
come out of the microcontroller and use it to switch a MOSFET completely ON
and so put a voltage across the inductor under test.

My circuit uses a TLP250 opto coupler to obtain the required 12V drive to fully switch on
the FET. 5V is not enough.

I need 2 signals, which are displayed on the DSO.
Yellow trace is the 5V pulse from the Nano uC
Light Blue is the voltage across a 0.02 Ohm resistor that is the last thing
in the circuit that charges the inductor before Ground.

We could test the chokes (or inductors..) at far higher voltages
but things are simple and easy when I do it with a 12V supply.
eg. 2x the voltage is the same as 1/2 the pulse time.

The basic inductance equation used in testing the devices is
L = V x t/I

L is inductance, in Henrys
I is current, Amps
t is time, seconds
V is voltage, Volts

In practice, we will look for the change in current that occurs during a
period of time.



I see the pulse length is 150 uS
I also the the change in current is about 1.5V across the 0.02 Ohm current sense
resistor. This is about 1.5 / 0.02 or 75 Amps  (V = IR and of course I = V/R etc..)
Volts is 12.1 V from the bench supply.

L = 12.1 * 0.000150/75 = 24.2 uH
The BK Precision LCR meter has it at 24.6 uH
The current increases linearly and in a nice straight line too.

I like to see measured results illustrate theory so nicely as in the above graphic.

Now when I increase the pulse width a fair bit, we can see the current increase a lot faster over time after about 180 uS. This is when the choke is becoming saturated.
It still IS a choke, with some inductance. But it's value will be a lot less than when it was not saturated.



260uS, 5V over 0.02 Ohms, 12.1V supply
L = 12.1 * 0.000260 / 250 = 12.6 uH




this is the schematic I used for the PCB

Schematic_inductor-tester_2026-05-31.zip


Edited 2026-05-31 13:37 by poida