Hello Today I'm charging the power Queen 12.8 volt, 100 amp hour life Pro 4 battery using the Sj20 power supply fed from a solar panel. Now this is a flexible solar panel. It's an odd one. actually.

it's um, got 32 cells. now. Normally these panels have 36 cells, but it does claim that the maximum PowerPoint is 17 volts. Let's have a look.

Yeah, so this is a 100 watt panel. Allegedly, 17 volts is V Max power IMAX power is 5.9 amps and then you've got a short circuit current of 6.1 amps because we won't see that because we're trying to get maximum power and I'm running the gauntlet a little bit between Sun and clouds. but let's see how we get on. Oh pretty good.

78 Watts by setting the Mppt voltage to 17. let's take that down to 16. at 74 Watts back up to 17 volts, 76 watts and if I take it up to 18 volts, it falls off again. So you can see we're trying to find this elusive maximum PowerPoint by setting the voltage at which this power supply puts on the solar panel in order to get that voltage.

So it seems that the maximum PowerPoint is somewhere around 17 volts. I Think we have a cloud. Of course, just after the cloud disappears, we get the maximum power and then that drops down gradually as the solar panel warms up. Because as panels warm up.

Oh another. Cloud I'm afraid. Okay, yes, as solar panels warm up their potential difference, their voltage drops. The current isn't affected in much, the sun's come out again.

But it does mean that the power drops off because of that drop in voltage. Can we get 80? Watts Not quite like I Say when the Sun goes behind the cloud, the panel cools down a little bit. Let me just get a little burst of extra power before it settles down. Unfortunately I Can't do anything about the flickering of the display.

It's a cloudy moment now. but I Just wanted to look at the other values on here. We've got the output voltage. Now that's essentially the voltage of this battery when current is Flowing It will look a little bit higher here because there's a bit of Vault drop in these cables, but the battery is at 13.3 volts the input voltage, the voltage coming from the solar panel 16.2 and the set point.

The solar panel voltage always seems to be a little bit below the set point, but the set point is set to 17 volts. The sun's coming out from behind the cloud does seem to take a little bit of a while for this to get up to maximum power as it allows the solar panels voltage to creep up. Yep, there we are. That's maximum power.

about 78. Watts Why is it dropping off? There must be some hazy cloud. Yeah, the sun's just sitting on top of a cloud, so it's uh, kind of half behind the cloud and half knot. I'll wait until it we get a bit of clear sky.

now. When I had this panel connected directly to the battery I was seeing six amps. but you mustn't be deceived because although I was getting a bit more current, I was getting a lot less voltage because the panel would course be pulled immediately down to the battery's voltage of 13.6 and not allowed to float at this higher voltage of about 17 volts. So although I was getting more amps and I'm getting less amps in this scenario, if I press and hold this, you can see I'm getting more watts.

So this is doing its job. It's allowing the solar panel to float up to its maximum power point, passing that through the efficient in this case Buck converter because I've got a high voltage on the input than the output and pushing current into the battery on the output. this Watts figure is the output Watts Actually, so the input Watts will be slightly higher because there is a bit lost in the electronics I just nudged this Mppt point up to 17.8 I Don't think that's helping, so let's take it back down to 17. Yeah, I'm getting more watts.

Um, Interestingly, if I take that all the way down to about 13 volts, which is what the battery voltage is, we don't lose that much power. 63 Watts at 13 volts of solar panel voltage and at 17 volts of solar panel voltage, 70 Watts it I was getting 80 Watts before why is that? Is it not a completely clear sky? Well, it's clear where it's clear. I can't look directly to the sun I Don't want to put my camera directly at the sun either. So at 70 Watts Um, the heatsink is warm, but it's not.

um, uncomfortably warm. Press and hold that to get amps. 5 amps is quite a low current. This allegedly can take 20 amps, but you do need air cooling.

These capacitors were getting hot when I was testing it at 10 amps. That's interesting because they're not warm at all now. So I wonder if they're just getting air cooled because there is a bit of a breeze? Now can we simulate uh, the sun coming up in the morning? Well, not directly because I'm just going to shove this connector in and um, see what the power supply does except boots. It should turn on the output that red LED there is on and yes, it immediately goes up to the Mppt point.

The Mppt lead is also on and we'll play with trying to make that go off in a minute. Um, but yeah, that shot up to the 73 watts. Can I improve on that 73 Watts Down a bit on the CV point? not really up a bit on the CV point. No, that's definitely gone in the wrong direction.

Definitely seems to work best at around 17 17 and a half volts. Oops, There's a bit of pots a little bit um, not very smooth. That seems to be the maximum. Now if I turn down the constant voltage on the output pot, you can very quickly get it to just collapse away to nothing.

So we're probably limiting the voltage on the output to a couple of volts. Now, raise that back up and that feedback loop doesn't interfere with the Mppt feedback loop. In terms of the current part. If I turn that down.

this is another one where it's not very smooth actually. I've got a screwdriver here. Let's use that. Uh, turn that down.

Should see the CV LED Come on. that's the one directly above. Yes, it's Come on. Now you just see it glowing red directly above the red.

LED here. CV LED has Come on. and we've lost power output. So you really don't want to be current limiting on the output either.

So we'll raise that up so that we're not current limiting and we're back up to 70 watts. Can we get a bit more by raising up the output? Con: The output voltage limit? Not really. No, so that looks like it's about the maximum we can get.