73 Amps and it's on Absorb. That battery must be quite large.
congratulations with the 10 MW.hr
Soon we can see you get to 20 MW.hr during your Spring and Summer.

G'Day Guy's,
           Well I'm getting on with my build of this MTTP and always waiting for that slow boat from China to get parts so the quest to find a right core for the choke took a new turn this morning.



Found 3 of these in that old grid tie inverter and there was a bit of weight in them so I just had to take what ever was in there out for a look  





75x35x30mm with a 14x53mm slot and that important gap builtin for the core, I do think by stripping another one I can put it side by side to make a e-core or would just placing it inline to get more thickness would be best?

Cheers Bryan
Edited 2023-03-17 10:23 by Bryan1

Hi Bryan, how easy was that potting compound to remove ? Hpprox how many turns and what gauge wire was used for their winding. I have a few of these and was going to strip one down to see what was inside too.

  wiseguy said  

Hi Bryan, how easy was that potting compound to remove ? Hpprox how many turns and what gauge wire was used for their winding. I have a few of these and was going to strip one down to see what was inside too.

In order to get out I just used my leather knife and cut down every side then just used a couple of screwdrivers to raise it up. The first one took a bit of time but the next 2 were done in half the time so now I have 3 of those cores.

I just used my angle grinder to cut on the side of the core which was 1mm wire and I didn't bother counting the turns. Then I used my pliers to get the wire out where I netted close to 1.4 kg's of copper wire.

I do have some 7x5mm enameled copper which is the same wire they use in 3 phase mig welders and off reading 11 turns was the go so no problems fitting that in the slot.

I found your schematic and I downloaded the xls file for the parts list and added each R number and off the xls file that link to get the 10x5 M4 seats off ali site but man $42 of 6 of them delivered OUCH  

Cheers Bryan

Now as I'm going to need a heatsink for the fets I found this




To use and I reckon it should do a good job of keeping those fets cool
Edited 2023-03-17 12:02 by Bryan1

Hi Bryan you said that "10x5 M4 seats off ali site but man $42 of 6 of them delivered OUCH"  
I used the link below and it said $4.70 for 20 pieces & shipping $7.73 ?

https://www.aliexpress.com/item/32811408567.html?pm=a2g0o.cart.0.0.777d3c00ckHnF0&mp=1

I deduce that we must be talking different items can you enlighten me more about that costly part, something sounds wrong?

Hi Mike,

I just had a look and it does look like 120 of them are on the way, O'well plenty of projects to do and won't run out of them very soon.

Cheers Bryan

Those cores run silent when the strap is left on.

Bryan, I did a post way back how to make a decent choke with two sets of the cores you show.
Its better to fit two of them side by side (rather than on top) as that gives a much larger radius for the coil which is then easier to wind with thick wire.

7 x 5 mm copper (35mm sq) would be good for a conservative 140 Amps, good find.

  Murphy's friend said  

Bryan, I did a post way back how to make a decent choke with two sets of the cores you show.
Its better to fit two of them side by side (rather than on top) as that gives a much larger radius for the coil which is then easier to wind with thick wire.

7 x 5 mm copper (35mm sq) would be good for a conservative 140 Amps, good find.

Mate if you please find that thread you describe I will be miles ahead of this slow boat from China.

Regards Bryan

G'Day Guy's,
           Well as it does look like these cores can be used for a choke I do have to say I do have a box from long ago with that yellow winding tape that isn't sticky so in the morning I will do a count of the rolls so I can offer some members with a roll or 2 of it.

When we rewind these found parts isolation is the key and this tape will do it so if it can help out I'm happy to go ahead with this.

Cheers Bryan

G'Day Guy's,
            Finally got some time arvo and did a count on that tape and the 20mm wide I have 20 rolls of so i am happy to give away 10 rolls to members. I got this tape about 15 years ago when i was repairing industrial gearbox's and a sister company moved in and this tape was thrown in the bin saying it was past the use by date. The start of the roll I opened did separate and a turn of 2 later it became good so i reckon this tape is still good to use.





Using some of the 14mm tape I have here I wrapped up 2 of those cores and taped them back to back as Murphy's friend suggested.



 

That copper wire I have is in fact 6x4mm so 24sq.mm and with the height of 14mm I should be able to squeeze the wire thru for 11 turns.

Cheers Bryan
Edited 2023-03-18 16:42 by Bryan1

14 turns through that is probably enough.
Enough inductance and the core seems to have enough area for a high enough saturation current.

time will tell. But a current sensor in the inductor circuit and an
oscilloscope with the mppt running at your required load will prove
it's good.

Hi Bryan I would be happy to take a roll (or even two if there is little interest shown) and I am also happy to help you out by relieving you of a bag of 20 of the M4 PCB connectors - tell me how much to send you for supply/postage, PM me if you don't want to clog up this post.

G'Day Guy's,
            Well the choke is wound  





got 10.5 turns using new 6x3mm enameled wire and I do have another length so I can do a join and solder it so I can get those few more turns if needed.

I live in the Adelaide Hills so for SA guy's a drive up the hill will save postage, those M4 connectors haven't even left to get on the slow boat so still no ETA.

Wiseguy if you want I do have some 6mm, 14mm, 20mm and 25mm rolls so you can have one of each and 2 off 20mm if you like.

Cheers Bryan
Edited 2023-03-18 18:00 by Bryan1

Hi Poida,
        Speaking of current sensors when I got the boards I thought YES I do have some samples of them. ACS754 and when I went looking for a datasheet there was a notice of discounted stock  

Well when I got them 14 years ago there were the rage, now looking at both datasheets my ancient mind didn't see much difference and the ACS758 is just the new generation of the same chip.

As far as a scope goes well I do have my Fluke 865 scope meter which I got back in '02 and is still going today even after a major Oop's   where many $$$$ I got new fuses and a new calibration. Also got an old scope thats gathered dust and I would be surprised if it still works but good stuff made back then were built to last so I won't be surprised if it works.

I will have to make a join on the choke just so it sits on the circuit board and a nice slow taper on each part then use some 2.5mm copper wire to make some rivets, I will put the flux on the tapers first then once it's riveted soft solder it as hard soldering is out of the question. If this choke gets hot enough to melt soft solder new wire will be needed a metre longer than what I used.

I did just did a check on my fluke meter and the choke is showing 0.36 ohms

Cheers Bryan
Edited 2023-03-18 18:57 by Bryan1

Hey Pete, can I please have a updated schematic if you have one??

Thank you in advance...

  noneyabussiness said  

Hey Pete, can I please have a updated schematic if you have one??

Thank you in advance...

which one? I am guessing the mppt.

sorry, Yes please

here is the mppt schem

Thank you...