Earlier this yr, throughout the concluding submit of a multi-part sequence that explored a not-as-advertised moveable energy generator, its already-broken-on-delivery bundled photo voltaic panel:
and the second photo voltaic panel I’d additionally purchased for the setup (and subsequently additionally returned):
I mentioned the first choices (serial and parallel) for merging the outputs of a number of photo voltaic panels, the respective strengths and shortcomings of the 2 approaches and, within the parallel-connection case, the additional circuitry that (until already constructed into the panels themselves) would probably be obligatory to forestall reverse-current hotspots in conditions the place one or each panels have been in dim light-to-darkness.
Since each panels I’d purchased, plus the moveable energy generator they have been meant to “feed”, have been all based mostly on Anderson Powerpole PP15-45 connectors:
the parallel combiner I’d additionally purchased from (and subsequently additionally returned to) Amazon had Anderson Powerpole connectors on each enter ends, plus the output:
What if something was inside it past simply two pairs of enter wire, with like-polarity cables soldered collectively and to an output strand, all inside an middleman watertight compartment? And if extra, why? Right here’s what I wrote again then:
Assume first that the combiner cable merely merges the panels’ respective optimistic and detrimental feeds, with no added middleman electronics between them and the electrons’ meant vacation spot. What occurs, first, if all of the parallel-connected panels are in shade (or to my earlier “darkish” wording surrogate, it’s nighttime)? If the generator is already charged up, its battery pack’s voltage potential shall be greater than that of the panels themselves, leading to attainable reverse present move from the generator to the panels. Additional, what occurs if there’s an illumination discrepancy between the panels? Right here once more there’ll be a voltage potential differential, this time between them. And so, on this case, even when they’re nonetheless charging up the generator’s batteries as meant, there’ll even be charging-rate-inefficient (to not point out doubtlessly damaging; preserve studying) present move from one panel to the opposite.
The consequence, described on this crowded diagram from the similar combiner-cable itemizing on Amazon:
is what’s generally known as a “hotspot” on one or all panels. Whether or not or not it negatively impacts panel working lifetime is, judging from the net discussions I’ve auditioned, a subject of no scarcity of debate, though I believe that at the least some of us who’re skeptical are additionally naïve…which ends up in my subsequent level: how do you forestall (or at the least decrease) reverse present move again to at least one or each panels? With excessive power-tolerant diodes, I’ll postulate.
These of us who suppose you’ll be able to direct-connect a number of panels in parallel with nothing however wire? What I believe they don’t understand is that there are in all probability reverse current-suppressing diodes already within the panels, minimally one per however typically additionally a number of (since every panel, notably for large-area fashions, is comprised of a number of sub-panels stitched collectively throughout the frequent body). The perhaps-already-obvious draw back of this method is that there’s a forward-bias voltage drop throughout every diode, which runs counter to the aspiration of pushing as a lot cost energy as attainable to the vacation spot battery pack…
Should you look intently on the earlier “crowded diagram” you’ll be able to see a blurry picture of what the combiner cable’s circuitry supposedly seems like inside:
And I closed with this:
Previous to beginning this writeup, I returned the unique combiner cable I purchased, since attributable to my in-parallel return of the Duracell and Energizer gadgets, I not wanted the cable, both. However I’ve simply re-bought one, to fulfill my very own “what’s inside” research-induced curiosity, which I’ll share with you in a teardown to come back.
That point is now. Since I strongly suspected my teardown could be damaging, I picked up the most affordable combiner I may discover on Amazon. This one, to be exact, from the identical provider I’d chosen earlier than (subsequently presumably with the identical “guts” in between the output and inputs):
On this explicit case, the combiner was meant to be used with Jackery moveable energy stations (traditionally based mostly on, as I’ve famous earlier than, both a DC7909 or DC8020 connector relying on the mannequin), so it included native-plus-adapter help for each plug requirements. At the moment’s affected person was “Amazon Warehouse”-sourced, subsequently $3.20 cheaper than the $15.99 record value. And once more, I assumed it wouldn’t reside previous my dissection of it, anyway. Talking of which, right here it’s:
Now freed, together with its related output adapter, from clear-plastic captivity and as traditional accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for measurement comparability functions:
Enter(s) finish:
Center thirds, high and backside:
And output finish, each “naked” and adapter-augmented:
Again to the center third for a aspect view. Look, it’s an ultrasonic welded seam all the best way round!
I’m glad to see that at the least a few of you loved my tried (efficiently, albeit not cleanly) breach of an ultrasonic-welded wall wart case initially of final month.
To the Hackaday crowd: No, it wasn’t meant as an April Fools’ joke. I had no thought what day Aalyia was going to publish it, though looking back, wonderful alternative, my esteemed colleague!
This time I made a decision to downscale my “implements of destruction” considerably, downgrading from a 2.5 lb. sledge to a extra modest ball-peen hammer, and to a extra diminutive however no much less sharp (sadly, this time absent a “hammer finish”) paint scraper:
I’d additionally wish to introduce you to my equally diminutive, not too long ago acquired vise, the surrogate for the Black & Decker Workmate I used final time. Isn’t it dainty (albeit surprisingly sturdy)?
It took a number of extra whacks than I’d have most well-liked (or possibly I used to be simply being cautious after final time’s outcomes), however ultimately I acquired inside, and cleanly so this time, if I do say so myself:
The opposite aspect…not a lot, though nonetheless not unhealthy (and sure, to a number of readers’ solutions, I additionally personal a hacksaw, which I’ve used earlier than in comparable conditions; I used to be simply angling for selection):
All that was left was a flat-head screwdriver appearing as a lever arm to pry the 2 halves aside:
And we’re in:
This preliminary perspective is of the underside of the system:
Observe the thick PCB traces and their routings. Preserve this in thoughts after we flip it to the opposite aspect:
Talking of which, let’s subsequent take away these two screws:
And the PCB’s now free:
Right here’s the underside aspect of the PCB once more, now absent the case half that beforehand surrounded it:
And right here’s the now-exposed high half, blurrily glimpsed earlier in one of many “inventory images”, that all of us actually care about:
Zooming in a bit:
And now even nearer, courtesy of my crude, cheap loupe-as-supplemental-lens setup:
These are certainly “excessive power-tolerant diodes”! Particularly, they’re multi-sourced (does anybody there know if the primary line “LGE” mark refers to LG Electronics?) MBRD1045 Schottky gadgets, variously referred to each “diodes” and “rectifiers”, the latter as a result of their Schottky-derived low ahead voltage loss makes them amenable to make use of in (amongst different issues) full-wave rectifier circuits just like the one seen in final month’s “wall wart”. Genuinely, the 2 phrases confer with the identical factor, as a dialogue discussion board thread I got here throughout in my analysis made clear. This memorable phrase in one of many thread’s posts cracked me up (no, I received’t reveal if I agree!):
EEs should not identified for consistency and exact language.
Admittedly, a circuit diagram I discovered in a number of suppliers’ datasheets gave me preliminary pause:
Two anode pins? Had been the same-polarity outputs of each photo voltaic cells mixed forward of the diode? And in that case, why have been there 4 diodes within the design, as a substitute of simply two?
Ultimately, even earlier than doing the mathematics and calculating that the spec’d 10 A of peak per-diode ahead present would barely-at-best allow free move of even one photo voltaic panel’s electron output (thereby, I believe, being the first trigger, vs the slight ahead voltage drop throughout the diodes, of my beforehand talked about inefficiency outcomes famous by some combiner customers), removed from two panels’ mixture load, I’d additionally realized that such a setup would solely obtain one of many two desired combiner goals. It could certainly forestall this situation:
What occurs, first, if all of the parallel-connected panels are in shade (or to my earlier “darkish” wording surrogate, it’s nighttime)? If the generator is already charged up, its battery pack’s voltage potential shall be greater than that of the panels themselves, leading to attainable reverse present move from the generator to the panels.
However it will do nothing to present flow-correct this different key potential “hotspot” situation:
What occurs if there’s an illumination discrepancy between the panels? Right here once more there’ll be a voltage potential differential, this time between them. And so, on this case, even when they’re nonetheless charging up the generator’s batteries as meant, there’ll even be charging-rate-inefficient (to not point out doubtlessly damaging; preserve studying) present move from one panel to the opposite.
So, 4 diodes whole it’s, two for every panel (one for the output and the opposite for the return), with each anode connections of every diode leveraged for a standard enter, and the 2 panels’ respective optimistic and detrimental pairs mixed after the multi-diode construction. This “digital man” could but evolve embryonic-at-least analog and energy electronics experience…nah. C’mon let’s get actual. Delusions are inexhaustible, don’cha know. Regardless, did I get the evaluation proper, or have I missed one thing apparent? Hold forth along with your ideas within the feedback!
—Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line publication.
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