Mabs 150v 45a mppt build

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Solar Mike

Joined: 08/02/2015
Location: New Zealand
Posts: 1130
Posted: 01:07am 28 Jul 2023      

1. How big can i reasonably go with the gap?

Once you get over 1.5-2mm with ferrite cores I have found little difference as the gap gets larger. 20Khz is really too low for that type of core, would work better at approx 100 Khz or higher, see if the code allows a higher frequency near 40 Khz or more.

2. I seem to recall advice against big solid wire due to skin effect - if you have 7 strand household wire (like the blue 25mm2 above) does that count as 7 in hand? or as they are touching and not insulated from each other, do they work as one solid wire?

The multi-strand un-insulated wire acts as a single strand, you require multiple insulated strands; I use 0.56mm dia. multiple strands (each good 1 amp) for best efficiency, least heating.

3. What do you use as gap spacers? Even with the clamp screws tight it gets quite noisy at 50A. Or can i use card, but with epoxy or similar to glue it in the final form?

Cut couple pieces scrap PCB material, 1.6mm standard thickness for your spacer, this wont compress as you clamp halves together.

Edited 2023-07-28 11:10 by Solar Mike