Picaxe 14M2 40 Amp Mppt Charger Controller

Solar Mike

New Member
This is an updated bigger brother variation of the 08M2 design; after starting the build of the old 14M2 design, decided to augment it for a higher current and voltage rating. Most of the circuit is the same except for an additional large low esr input capacitor, use 2 buck mosfets in parallel and allowance for various combinations of output capacitors. New specs are 40A continuous charge and input PV voltage up to 250V.

Here is the new cad layout: PCB 100 x 180mm24414

After building the very basic 08M2 design, decided to mount all power mosfets and dual diode off one edge of the pcb, they now sit under the pcb bolted to the alloy side panel acting as a heatsink. The mosfet driver card mounts soldered to the top mosfet pins, optimizing the drive layout and keeping all high current pcb tracks on the main pcb. Will now modify the old driver card for the additional mosfet.

Main reason for the changes are the new PV arrays that will be installed are sets of 6 x 285W panels; ie. parallel pairs of 3 series, resulting in 94Vmp at 18 amps, this will convert to approx 33 amps, 48 volt bank. The old design would just manage this but not continuously, having an extra input cap and buck mosfet allows better heat dissipation and lower losses. Track clearances have been increased to allow PV voltages up to 250V, so I can use the design on a 100V Lifepo4 bank.

Will update this thread as the design evolves.

Cheers
Mike
 
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Solar Mike

New Member
Here is the small driver pcb module that sits on top of the mosfet main pcb pads. I have allowed for an optional synchronous rectification mosfet rather than using dual Schottky diode.

More soon....

Cheers
Mike

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Solar Mike

New Member
Thank you.

Any chance there's a Gerber file somewhere?
Was going to get pcb's made and tested first, however if you want to have a go at building it, contact me with your email and I will send them to you.
Note I dont have a complete schematic nor any software as yet; so you will be on your own there.

Cheers
Mike
 

papaof2

Senior Member
Was going to get pcb's made and tested first, however if you want to have a go at building it, contact me with your email and I will send them to you.
Note I dont have a complete schematic nor any software as yet; so you will be on your own there.

Cheers
Mike
I'm happy to let you test the PCB ;-)
 
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