Part2: Testing ZK-SJ20 Buck Boost MPPT Function

How does the MPPT potentiometer on the ZK-SJ20 buck boost converter work?
Power Queen 100Ah LiFePO4 Battery:
uk.ipowerqueen...
ZK-SJ20 Buck Boost MPPT Converter 300W
www.aliexpress...

[@E9Project]

I love the channel and this board looks interesting, ill be needing stuff like this soon and im very glad you cover these things. Keep up the great work! 👍

[@jlucasound]

He KNOWS Stuff. Julian Ilett is an expert.

[@E9Project]

@@jlucasound I have watched for a few years now, love it :)

[@ericchang7706]

Thanks Julian. I'm enjoying all the coverage you are doing on this Buck Boost device.

[@MiniLuv-1984]

Thanks for a marvellous demonstration of the behaviour of the PV panel with temperature and mpp voltage. That was very good. It seems to me that cooling the panel (with air or water say) amounts to an improvement comparable to adjusting the voltage for mpp. Given power is required to cool the panel by running a fan that will draw a fair amount of the power improvement from cooling, then besides mpp tracking only a passive cooling system will help boost performance.

[@diydsolar]

Great! Waiting for these tests with high currents. For example charge from your 12v battery a 24v battery. Thanks a lot

[@JulianIlett]

I've only done one test so far at full current. It maxed out at 13A - a bit disappointing. That was 13.2V in and about 13.6V out (into the same 12V LiFePO4 battery). It needed fan cooling with the Ryobi fan to keep cool at 13A. I bought some 5V fans but they're feeble - about 100mA I think. I'm now looking for some more powerful 5v fans.

[@diydsolar]

@@JulianIlett great test ! Probably apart from 300w maximum it will have a maximum input current.

[@JulianIlett]

Update: It seems there maybe a pre-set current limit on the input. Looks like about 10 amps. Using 25V on the input, I got nearly 17A into a 12V battery on the output.

[@diydsolar]

@@JulianIlett great thanks a lot, , and the other way round? 12v to 24v ? We want a new great video!

[@Patriarchtech]

Hey Julian I love your videos, I own four of these units, I love them - Probably buying 4 more. I live in Japan and doing a balcony solar setup. I want to have one of these units for each of my 8 x 110w 20voc 6.12a Isc panels. So far it works great with Schottky diodes on the input and output of each unit in a 24v system running 4panels in 2s (40v 6.12a isc) to four of these units. One thing I will say is you need to be a little careful with the pots. The display shows one voltage on the output and my multimeters two different ones show another(same on both). Not a deal breaker at all, but certainly you wanna make sure the output voltage limit is with in standards of your battery.

[@jeroen2344]

Looks a lot like your early experiments with the mupped are you here also going to replace the pot with a arduino to auto find the mppt point?

[@JulianIlett]

Yes, they should make a smarter controller board with full MPPT tracking.

[@StephenBatchelor-l5m]

Thank you Julian, I have enjoyed all of your videos so far. I do have one question: what happens when the sun starts to shine on the panel first thing in the morning? Does the ZK-SJ20 boot up reliably?

[@chrisnegociosia]

Very good video, what happens if you disconnect the power from the solar panels? Are the output settings you made saved for the next time you connect the panels?

[@riobravo2267]

Very helpful, great explanation 👍 but I was wondering if you also could regulate / optimize the power output from a solar panel with a boost-buck mppt power supply module. I've installed 2 dc 500W 48V 10Amp heating rods in my 120 liter water heater. They both have their own 550W 44V 13Amp solar panel directly connected to them. On a sunny day (Oktober) between 10:00-16:00 (6 hours total) it increases the temperature with 20C°. So nothing else in between. Just a solar panel, 2 wires and a heating rod. In my case, would a boost-buck mppt module improve the overall performance? Thanks, greetings John, Netherlands

[@JulianIlett]

I like the simplicity of your system. An MPPT buck boost is unlikely to improve it.

[@riobravo2267]

@@JulianIlett Thank you for the quick response 👍 I watched you holding the module in the video as it was getting warmer. That's probably also the bottleneck in my case, drawing continue power with the heating rods. I leave it the way it is, for a simple, direct pv setup like this I'm satisfied with the result 👌

[@electro2606]

You can also set the cc to the current is max 300w

[@lithiumionkid851]

Could I use this as a controller for a wind turbine? The wind turbine could reach around 450w, would it work if I took the display off and gave it some good cooling power? What would be even better is if I could modify it to track the rpm of the turbine and control the mppt pot!

[@cmyanmar13]

Hi. I'm curious what is this module's passive current draw from the battery when the solar panel is disconnected?

[@JulianIlett]

Probably near zero because it's powered from the front end - i.e. the solar panel.

[@georgef7754]

So, being a bit confused, my question is can I safely use this for an unattended charge of my 24v lifepo4 battery with a solar panel Vmp of 17.5V and Imp of 9.7A? Thanks.

[@daijoubu4529]

You can't, it's not a charger, it will trickle charge once fully charged, you'll want a charger specific IC/module, Consonant makes a few, some probably have LiFePO4 voltages or are adjustable

[@lobbiedove5014]

Having a bms how would the battery charge with no controller, directly from the 12v" solar panels? Thanks

[@CHRISTIANIANTAN]

can I use this module to power an AMD motherboard (around 165w MB plus 65w processor)?

[@plan9channel7]

I have one of these for my 200w solar. It works well but , I have to turn it on all the time. A big pain.

[@jlucasound]

Julian. Put "Hot Water Bottles" or similar, on the backside of your panels. Run a water pump in series and through a cooler of ice. If that works, get Pel units to cool the hoses carrying the water. Zig Zag, very flexible hose. Just thinking. I know. The power to run the peltiers may be more than you gain. Make it really efficient. Thermal brainstorm! Spray foam, aluminum foil. We know you can do it.

[@JulianIlett]

Using pumped water to cool solar panels is like building tracking mechanisms to follow the sun - just not worth it. It's cheaper to buy more solar panels.

[@sjames1958]

I wonder whether this device could be used to make an Enphase iq7+ grid tied inverter a bit more intelligent. Battery >> ZK-SJ20 >> Grid tied inverter >> house AC. You'd be able to control AC wattage, all be it manually.

[@JulianIlett]

No, don't do it.

[@sjames1958]

@@JulianIlett please explain why you think not?

[@JulianIlett]

You could be breaking the law - you'd be breaching the MCS certification. The microinverter expects to see a solar panel on its input and a mains connection on its output. Anything else is outside its design spec. On the other hand, it might work. But I don't play with mains.

[@sjames1958]

@@JulianIlett Ahh ok nothing specific then, grand... Thanks. Law isn't quite the right word but I guess you mean the G98/99 ENA type test where you say MCS. Interestingly have you seen Octopus has removed the MCS requirement as wiring regs cover it all. The spec of the kit is 16-60v and constant max 12a so keeping well within that. The kit just sorts out the DC in so it outputs AC. There are a good few grid tied inverters on the market that use solar and/or battery to push AC in. Anyway thanks for your comments.

[@jlucasound]

Bypass the 300W limiter? Julian, you rebel, you. 🏍🐻😀🥰

[@JulianIlett]

I'm not sure this thing could ever get to 300W :(

[@mixeI1992]

I have a question, can I use this to convert 12v car socket and limit to 80w to charge a lipofe4? Thank you

[@JulianIlett]

Yep

[@VincentBernabucci]

This Is exactly what I'm doing to power my audio system in my 16v tesla. 😉

[@jamess1787]

Hows the crypto mining shed doing? Have any more runtime from any upgrades?

[@JulianIlett]

Nothing yet. I'm building another big battery - 8S5P of 6Ah LiFePO4 = 768 Watt hours. I'll put that on the other solar panel. That should increase my earnings from $0.03 per day to $0.06 per day :)

[@JulianIlett]

Interestingly, The Litecoin halving didn't affect earnings from the Antminer L3+

[@Patrick-kt8em]

Would anyone mind explaining me why there is a voltage adjustment for the mppt? What is the point of mppt if you have to track the voltage manually all the time? I have never seen any mppt where you have to adjust the voltage manually

[@tempest49656]

This is mpptm - tracking manually, not mppta - .. automatically :))

[@daijoubu4529]

This is a pseudo MPP - minus the tracking part. PV panels have a Vmp and this converter loop control only controls the amount of current pulled to keep the set input voltage

[@MrCalldean]

Comments on the last video were.... critical, maybe? But very little feedback from you Julian?

[@JulianIlett]

Which video?

[@MrCalldean]

@@JulianIlett Part 1 of this - don't get me wrong, love your videos (Even the ones that go over my head), but was surprised at the difference in engagement between vids.

[@JulianIlett]

Ah I see. A few comment that it's not real MPPT, but since I made that pretty clear in the video I didn't feel it was necessary to repeat myself in the comments. On the other hand, part 1 did get a lot of views :)

[@MrCalldean]

@@JulianIlett fair enough. That's explanation enough for me. 😂