Tales from a Ventilation Lunatic

[sternwake]

I arrived back in California a few nights ago, and found a 180mm fan grille I purchased a while back for the FM181, which was way too small for a 180mm fa, is actually designed for a 140mm fan. I had painted it black when i got it too, as these do rust in my environment.

I have not yet modified my shroud for the larger 140mm fan, and will not do so until the Marine Amazing goop is no longer stinky. I applied it tover the solder joints where the wires enter, as I will do to every fan from now on.

I have discovered aother fan failure however, the 60mm Noctua fan mounted to the lid of my Meanwell rsp-500-15 adjustable voltage power supply, which I use as a charger, is not spinning. So it looks like i get to open up another email chain with Noctua regarding its replacement as it is still well within the 6 year warranty period.

So it appears removing the 'N' wrd from thread title was not effective in reducing my fan failures.
I had opened up my HVAC blower motor to free up the stuck brushes, and when driving through east Texas, the thing quit working again, and once again I found the brushes stuck in their holders. I reduced their size slightly with some worn 220 grit sandpaper on a block, lubed them with dielectric grease and all is working again.

Getting this motor apart requires bending steel flanges upwards, and there is not really a good way to do so, and they need to be tamped back down afterwards. I expect they would snap off after one more opening and closing so this time better be the last time I need to open up this POS blower motor. I could likely cut new tangs with a dremel and reindex it if I had to, but I better not have to. Removing and reinstalling the blower motor is pretty easy, but I do have to remove the upper half of my radiator shroud and slide it to the side to get the motor completely out. This is not all that hard either, just 4 bolts relatively easy to get to.

I located the counter rotating 120mm arctic cool fan in my workshop, but have not yet wired it up or installed it to push air into the silverstone fm121. this fan is a PWM, and thus it too can be speed controlled, but I need to run a 5v PWM signal wire upto it to do so.

I have cobbled together such a device in order to do so, in the past, but it is not very efficient, and the Noctua speed controller is much mroe sleek, but it is employed in my intake fan shroud. I could speed control this counter rotating fan in parallel with my intake fan(s) but it would be better to have it independently controlled. I could do so now with the voltage bucker and PWM signal generator I set up, but these two devices together are bulky inefficient, and do not seem to allow the minimum speed that the noctua NA-fc1 controller allows .

I've got some ideas to increase roof exhaust flow further, basically by cutting a new hole and making my own mushroom style vent. I want one or two of those Pabst 283 cfm fans, even though I do not really require more ventilation. but I'm an addict.

[rvpopeye]

Ahhhhhhhhh
So now we get to the root of your chord....
Your title needs to be Ventilation Addict , without a doubt.  

Although enthusiast needs to stay to....

The Enthused Ventilation Addict....naaaaaaahhhhh

Just Need Air , nope.

Fan Man , eeeeewwwwwwwwwwww

All too meh.

The Ventilation Nazi  , now
THAT just has true grit.

You even get to say
"Fan For You !"

OR of course...
"NO FAN FOR YOU ! (Mr.61)" 

.

[sternwake]

Arrrrrrrrrrrrrrggggh there be ventilation in your future mateeeeeeee!!

Good News on the 60mm Noctua, The positive wire simply rotted off the circuit board, encased in green fuzz.

Another fan sucumbs to the green corrosion at the wire entry.

But I nipped away at the hub with some side cut wire cutters until I could see well enough to get a soldering iron in there to reattach. I bridged the red and yellow wire entry, the yellow being a rpm signal to the non existent computer mother board. This was unintentional and undesirable, and remedied after the multimeter confirmed my suspicions.

This wire entry is now submerged and encased with curing Amazing Goop. The inside of the Meanwell Power supply had some badly impacted dust in a few nooks and crannies.

The Arctic Cool f12 PWM fan is installed.

https://www.arctic.ac/us_en/arctic-f12-pro-pwm.html

I had one of these fail, but it was 11.5 years old and colored differently. the special mounting rubber feet which hold the hub to frame had long broken off and screws and Zipties took over.

Which caused me to buy a newer one half that age, which lasted but a few months before failure, cause not determined or remembered or both.

The original was then reemployed and only failed recently and the one employed today was bought mainly as a backup, and since it had PWM speed control, I might employ that feature. I did add a PWM third wire to the blue when I soldered red and black so the speed control option is still there. It is much quieter than the recently failed unit, due to rubber mounts replacing screws and zipties. It also places more space between it and the silverstone fm121 it is feeding.

Me thinks this extra 5 to 8mm distance betweeen counter rotating fan blades is Mo betta from airflow and perhaps noise perspective. Unfortunately these rubber feet are all too easily broken.

[rvpopeye]

The plot thickens ,,, should it be called stew ?
Tune in next time for the next episode of "I kill my fans 4 U".
Brought to you by our "Ain't Right" sponsor "Boondocking Science" coming soon to a forum near you..... baaaaahahahaha.
Full speed ahead arrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr
(Do we have any torpedoes left ? I don't knowwwwwwwwww.)

[sternwake]

The 80mm Noctua fan mounted to the lid of my Meanwell power supply as an exhaust fan, got cleaned and its wire entry points encased with Amazing Goop. There was enough impacted dust inside the Meanwell that I bet had I left it to accumulate, then one high humidity day could cause shorts between internal components I suspect impacted dust was a contributing factor to some previous fans' failures, and why I seemed to suffer so many faiulres shortly after I arrived in Florida's humidity last November.

I'll be very sad when this meanwell powersupply fails. It turns 5 this october and has a LOT of use on it.

I broke down and ordered one Papst 283cfm fan. I do not really need this fan, but I need to know how it responds to the voltage buck/boost unit I already have, and how much wattage it actually consumes maximum, and at the speeds i am likely to use it at. Then I will figureout if and where and how I will employ it.

Fan 10$ shipping 15$. Oh well.

The Arctic Cool f12 counter rotating fan feeding the SS fm121 is so much better than the SS fm121 alone exhausting my ceiling. It is amazing how much quieter the fm121 fan at highest speed gets when the AC fan is turned on, and the amount of air that comes through the slowed intake fans also increases noticeably.

[sternwake]

The Papst fan arrived. 

it will start spinning on 7.5 volts, but once spinning one can keep it spinning slowly lowering voltage  to about 7 volts, it makes weird ticking noises down this low and moves next to no air..

@7.6v it draws 0.09 amps
@8v it draws 0.16 amps
@9v it draws 0.25 amps
@10v it draws 0.31amps
@11v it draws 0.35 amps
@12v it draws 0.46 amps
@12.8v it draws 0.51 amps
@13.6v it draws 0.55amps
@14.4 it draws 0.6 amps
@14.8 it draws 0.64 amps
@ 16v it draws 0.72 amps
@17v it draws 0.8 amps
@18v it draws 0.91
@20v-----1.11amps
@21v-----1.2 amps
@22v------1.32amps
@24v-----1.62amps
@25v------1.72 amps
@26--------1.83amps
@27--------1.97
@28--------2.06
@29------- 2.21
@30v-------- 2.37
@31-----------2.57
@32v----------2.75
@33v ----------2.99amps

My Drok voltage buck/booster is rated to 33 volts output, but actually goes higher.  Seeing as how the amperage was gaining another 0.25 amps with every volt over 32,  I did not bother to test upto 36v.  The rpms did not seem to really increase proportionally with each volt over 31 so i would not really want to run the fan much faster, seeeing as how the amp draw went way up.



The exit  airflow is relatively concentrated in a column. placing my hand close  in front of it does not alter the sound of the fan or change its speed, but behind it and it does.  This should be a good fan for blowing against restrictions

The 252cfm 120mm screaming banshee Delta fan moves air at higher velocity.  This velocity makes it seem to move more air.

Side by side I cannot hear the Papst fan at all, when the screaming banshee is getting 13 volts, even with the papst fan getting 33 volts.

The air movement at 12 and 14 volts is still impressiive, and the amount of air moved at 12V FOR 0.46 AMPS, is a lot, in comparison to a 120mm 0.6 amp fan I employ and i is much quieter.   I think users could use this at regular 12v battery voltage or less, using only a bucker/voltage reducer if they wanted.  I really want the turbo ability of 30 volts, but the air moved at 12 volts is still impressive, and it is quiet compared to 120mm fans moving the same amount o air.

Obviously the higher the voltage the more noise and amp draw and air moved. 33 volts and the air moved is likely 283 or  higher, but I have no way to atually measure it.

So while the fan is listed at 1.1 amps, I only drew this around 20 volts input and was upto 3 amps at 33 volts.

I was not using short thick wiring to the drok buck/booster.  22 awg zip wire and likely 10 feet of it, for testing.  no doubt some losses there.  I do not think the Drock buck booster is a very efficient one.  It did not seem to get very hot boosting 12-13 volts to 33volts  for 5 minutes passing 3 amps. its rated for 5 amps or 80 watts. 

My  Clamp ammeter was on the wire feeding the drok, not the oe coming out of it, so the voltage was 12.x x 3 amps for ~37ish watts when the fan was fed 33 volts through the drok

https://www.amazon.com/DROK-180050-Stabi...5AC8XGJ1GG

I did run the fan directly from a 100 watt solar panel @3pm , in cloudy skies  through the drok and things went haywire when i dialed in over ~18 volts.  I was glad to see the drok recovered when attached back to a battery but I thought i smoked it..

The fan comes with a weird 5 wired pin barrel type of plug.  there are red and black wires inside of the 5 wire sheathing.  I did not test the fan before cutting the connector off.  probably should have.  not sure what the other 3 wires are supposed to do.

It makes a weird noise on initial fire up, and every subsequent from a dead stop.

The tips of the fan blades is likely within 1MM of the fan body.

I've not yet inspected how to remove the impeller a gain a look see at the guts.

Not yet sure how I am going to employ this fan, yet

[sternwake]

I wound up routing out one 120MM fan hole on my acrylic intake shroud, bigger, to accept the 140MM 3k rpm industrial Noctua Fan.

While working on this and routing wires, i had the E Papst fan running at various voltages/ speeds/noise levels nearby, and have readjusted my opinion on its noise levels at reduced speeds.

There is no way I could employ the Papst fan at slow speeds inside my Van, the motor noise is significantly more than the computer muffins fans at slow speeds. I think the Papst would be fine if a wide airflow range was desired and low rpm speeds if the fan was far enough away to not be an issue. but I do not believe I would use it to replace my current fan set up exhausting my ceiling. Perhaps in parallel when hot and required, and closed off and powered off completely when its additional airflow is not required.

At higher speeds then the papst fan can move significant air for less noise than the computer fans at their higher speeds and similar airflow levels.

I can easily sleep with the Fm181 and 120 and 140mm Noctuas at their slow to even medium speeds mere inches from my ears, but the papst fan could not be tolerable slowed as slow as it could go, in this same location.

The extra 50 CFM and static pressure rating of the 140MM noctua warranty replacement is quite apparent. If I have my ceiling exhaust counter rotating fans on high and the 3 fans in the intake shroud on high, and all the doors closed, opening the side door changes the tone of the intake fans dramatically. If I try and close the door , just keep it cracked, the fan's pressure will open the door further, and If I stand outside the door and push it close to being closed I can feel the air gushing out around the open door. This was also apparent with the two Noctua 120mm fans, but the 140mm fan replcing one of the 120s made the effect much greater.

When i employ the 2 shrouded fans in my passneger side front window as exhaust fans on high speed there is still a bit of air that gets expelled out the side door.

When I had the shroud out for modification of one 120mm hole to a 140mm hole, I realized I could indeed employ two 140mm fans in this shroud and will likely ask for another 140mm Fan when the industrial 3k 120mm Noctua fails, like its three brethern did.
The 140Mm Noctua fan has yet to spin up backwards on intiial powering up, leaving me to hope it is not as susceptible to failure as the IPPC nf-f12 3000rpm version.

[sternwake]

OK, the 4th IPPC 3k rpm Nf-f12 industrial Noctua fan failed a while back, and I returned a much lesser quality high speed high amp draw 120mm fan in its place, and only turn it on when such additional airflow is needed. I did cut out some plastic cutting board blockage pieces to slide behind the finger grill when not in use so the air the other fans blows inward, does not simply do a U turn and recycle through the two other fans again. Its impressive when I slide these blockers in place how much more air suddenly hits me in the face.

I just today contacted Noctua about this latest fan failure. We'll see if they continue with their excellent customer service. The former employee I had e mail chains going with has left the company. I asked for the 140mm 3k rpm industrial model as a replacement. The last one they sent is still working fine, and has never spun up backwards.

I have not yet employed the 24v E-Papst fan in my Van, but it is simply too good a fan for its 10$ price tag to only have one of. So I just ordered two more and am researching other buck/boost converters to take advantage of its full speed range, though the one I now use to control it might be the best overall option amazon offers for this application.

https://www.surpluscenter.com/Electrical...6-1553.axd

Surpluscenter charges a premium for shipping but one can add items to that order and shipping barely increases at all.

I saw they have some other fans I don't really need, but the price is too good. A Jaro 200CFM 120mm fan for 6$, I'll take 4 please. I plan on using two of these to replace the 0.62 amp 105cfm 'stinger' fans I use in my front window fan shroud. From 210CFM to 400cfm maximum. Yeehawwwwwww. That should keep the social justice warrior, relishing in their own fabricated rage types from thinking I am abusing Fiona.

https://www.surpluscenter.com/Brands/Jar...6-1556.axd

This fan is still below the 252 cfm of the 120mm delta Screaming Banshee fan, but the SB fan cannot be speed controlled very well.

On that note I am going to try a buck converter that has a current limiting pot as well as a voltage adjustment pot, to perhaps control the SB to tolerable levels.



This fan shroud will also soon be made of smoked acrylic and designed to be left in place when driving, and stay in place with window down. It only takes a few seconds to install and remove the shroud, but it would be nicer to leave it in place for around town driving. It should be noticeable enough parked and inconspicuous enough when driving to be left in place.

I bought four 92mm fans, these have a clear body and impeller and have 3 set speeds.

https://www.amazon.com/dp/B00066ISVQ/ref...UTF8&psc=1

I will have enough plexiglass left over to make a drivers side window shroud and have 4 of these fans pushing air in at various speeds, and the 2 Jaro 200 cfm fans exhausting on the other front side window of the van. Even with my tight fitting reflectix front window shades, the front of the van can warm up due to engine cover heat and the sun when I park facing Southwest while surfing and the front of the van is considerably hotter than the back, and Fiona prefers the front seats to reside while I surf, so some cross flow for up front should help up there stay cooler.

Each of the 80 92 or 120 mm Antec fans comes with a little three position slide switch one on about 6 inches of wiring one can choose to locate anywhere within that length. I think switching the 4 individual fans independently is going to be a short lived novelty and I will likely put them all on a voltage controller for twist a dial for infinite speed control for all 4, rather than 4 separate switches for 3 set speeds.

I suspect the Antec fans will likely be repurposed into a window shroud for other vehicles. There has been some interest by other pet owner surfers or shoppers in such a fan shroud., asking me where I bought it and how much it cost, even though black painted plywood hardly looks like a click order place item and I said I could not make a custom one for under 100$ and likely closer to 200, though some have certainly lost interest when I stated those figures.

I find everytime I park in my overnight spot now, even if it is not warm/hot, I set up this passenger window shroud and all my fans get their speed lowered for same overall amp draw and more cross flow air circulation. If it is hot and all fans on high have the interior very windy.

The surplus center wanted $17.67 to ship two E papst 24v fans and 4 Jaro fans, and adding four more of these 1.89$ 60mm fans brought shipping upto 17.99$.

NMB fans in my experience are well made, so for $1.89 I will find uses for them.

https://www.surpluscenter.com/Electrical...6-1507.axd

A 60Mm fan bridges the heatsinks on this voltage booster nicely:

https://www.ebay.com/itm/150W-DC-DC-Boos...100623.m-1

I have found this voltage booster increasingly useful lately and am looking at higher wattage versions that could perhaps handle powering the 'free' 24v hedge clipper dropped off at my workshop. I can use this hedge clipper to cut down the foxtails and rake and vaccuum them up easier and keep them out of Fiona's footies and other places.

[sternwake]

No reply from Noctua, Yet, about the latest industrial 3k rpm nf-f12 fan failure.

I spent some time shopping for voltage converters on Amazon and then Ebay.  I like shopping Amazon, but the price and selection on Ebay on buck converters, or boost/buck converters is quite superior.

Basically I use the buck converters/ step down  to speed control 12v fans.

The older buck converters I bought several of used the LM 2596 chip, which was rated for 3 amps.  I stuck a copper heatsink atop the chip as my previous fans could approach most of that rating, and keeping electronic cool is key to their longevity. 

https://www.amazon.com/Adjustable-Conver...way&sr=8-3

I tried to hotlink photos of the converter, but had all sorts of issues on 'preview reply' and nearly said F it and dumped this whole post with a slew of curses.

The little blue rectangular box is the voltage adjusting potentiometer.  Obviously busting out a jeweler's screwdriver every time I want to change fan speeds is not convenient, so i would desolder this device, and and 2 wire zip wire leading to a different potentiometer.

 W103  as printed atop this potentiometer corresponds to a 10k ohm potentiometer.  One can find these cheaply online.

Regarding this desoldering, it is more difficult than one would suppose as one needs to get the solder hot enough on all three legs at the same time, and pull it out.  When one accomplishes this, the solder tends to bridge the holes.  I would use a micro drill bit to ream out 2 of these holes, then insert 2 wires, solder them in and then to a potentiometer of the correct value.

now the pot has 3 legs, the replacement finger twist pot has 3 legs, and I am running two wires. WTF?

If one sets their digital multimeter to measure resistance one will find that two of the three holes have continuity between them. Of these two a single wire needs to go into only one of them.  One can do the same to the new potentiometer and hook the wires up temporarily and twist the pot, clockwise should increase voltage CCW decrease, if it is opposite move the wires as needed to get the CW/CCW right.

The above buck converter link it the 3 amp model.

Here is the 5 amp model.  it seems to be more efficient using a newer different transistor that itself is rated for 5 amps.

https://www.amazon.com/HJ-Garden-Convert...ay&sr=8-13

please note there are many  different brands/versions of this buck converter, and some of them use different value potentiometers, so Zoom in and look at the lettering on the blue rectangle and use your google-fu to determine the resistance value.  Use the links to put search terms into amazon and ebay and one can find significantly better deals of the same/very similar products.  E bay links tend to be short lived so the links above are examples.

I liked this particular version and the wirewound toroid lays flat on the slightly wider circuit board, rather than up and down as on many  others.  Also it came with the heatsink one can apply to the XL4005E1 transistor themselves.  Mine did not come with a peel and stick adhesive, but some others do.  I used super glue, but ideally I would have used some arctic silver thermal transfer epoxy.  unfortunately my AS epoxy had hardened in their respective tubes.

There are other versions of this buck converter that have two potentiometers, with the second being a current limiting potentiometer.  I have yet to play with such a version, yet.  Supposed to arrive Wednesday.

I want to see if the current potentiometer can control the 120mm screaming banshee 252 cfm fan to tolerable speeds and noise and amp draw levels.

I first tried to tame this fan with an 8 amp  PWM motor speed controller, but it would slow a little, then just shut off and its minimum speed was still way too powerful.  I then wanted to see if I could control this 3+ amp fan, by voltage alone,  but the 5 amp buckers were not available then, but this 5 amp buck boost converter was.

https://www.amazon.com/DROK-180050-Stabilizer-Transformer-Adjustable/dp/B01DXEU4KA/ref=sr_1_3?keywords=drok+5+amp+buck+boost+converter&qid=1566172185&s=gateway&sr=8-3



It too failed to tame the screaming banshee to my satisfaction. It just shuts down under 7 volts or something like that.

The SB also did not respond to the PWM signal generator I cobbled together, as it is a 4 wire PWM fan whose speed supposedly can be controlled by that blue forth wire, but I missed or messed something up regarding this and did not continue efforts.

So the 120mm SB fan is still untamed, but my 92mm fans scream louder and can move an impressive 175CFM at 12v, they also slow way down to near silent and very low amp draw, negating much of my desire for the SB120mm in my van, but in the workshop its flow would be appreciated, if it could be tamed.

It should be noted these voltage  buckers cannot pass 12.8v if they are only getting 12.8v. there has to be some degree of lower output than input, headroom, and I forget exactly how much loss these new 5 amp buckers allow, perhaps I wrote it earlier in this thread, but the 92mm 7500 rpm 175cfm fans are so powerful and loud that the loss of voltage and speed on the top end is of no consequence to my usage of them.

When i got the E papst 24v fan, I used my drok buck/boost converter on it, and fed it battery voltage and it can output anything from 5 to 32 volts.  The effective speed range of the Epapst fan is 7.6v to 30v.  I have yet to desolder the potentiometer of the drok bubk/boost converter and put a finger twist pot on it, yet.

This Epapst fan is impressive very well designed and built.  It is just not as quiet as a computer fan is when slowed way way down.

Mounting it, and attaching a buck boost converter and employing it in my van has yet to occur.  but I still ordered two more of them.

I am shopping other buck boost converters for these new arrivals.  A 5 amp model can power two of these fans, upto 30.5 volts, but 31 volts will be more than a 5 amp load, and likely fry the buck/boost converter.

Over 30 volts the e papst  fan speed does not increase at the same rate as each volt increase below that, but the amp draw does.  There is a 0.8 amp increase when fed 33v vs 29 volts, with very little increase in rpm and airflow from 29 to 33 volts.  I am not quite sure how to make it idiot proof so one can not exceed 30 volts and stay under the maximum 5 amp load that one of the buck/boost converters is rated for, if I were to try and power two fans off one converter. 
 Not really a big deal considering the price of the converters and the fact that I cannot even find a home for one of these fans in my van at this point, only my workshop.

My main workshop exhaust fan is a cheapo 115vac box fan, and I've been wanting a DC fan to make use of solar and battery instead.  Not sure the box fan's cfm rating on low medium or high, but it is something like 325 watts on low speed which is a bit ridiculous for the amount of air it moves on low.  I think I could use a lot less energy sticking two epapst fans in a shroud and exhause air more effectively and effieiently in the workshop, compared to this box fan whose open 4 corners  allow the pushed air to do a U turn, and reenter the fan again.

The E papst fan blades come very close to its housing, and two of these fans in a shroud exhausting will not allow any air to loop around, and they will be about 45 watts on max speed, compared to the ~325watts of the 20 inch 115vac box fan on low.

I got to go measure that again, that seems too high.  I did run it off an inverter through one of my wattmeters and that is the number I remember on low, and on high it was exceeding the inverters rating of 400.

Anyway this thread will have much added to it in the near future.

[sternwake]

Still no reply from Noctua. Hmmmm.

Kind of looking like another 140MM fan on my intake fan shroud, should they send one, might be quite the tight fit anyway. One of the new yet to arrive 200cfm 120mm Jaro fans might go there instead, on its own voltage bucker speed controller.

My Silverstone fm181 180mm fan, which had potentiometer problems back in February, is again having some issues regarding the range of speed I can dial in, especially on humid nights. Last night on low it was changing rpm by itself which i found annoying enough to put it on high. Good thing it is such a quiet fan.
Perhaps a circuit board cleaning with Deoxit d5 and a protective layer of s5 shield spray is needed. If this does not work it will get its own voltage bucker speed controller. I have a few extra 3 amp rated buckers and this fan only draws 0.27 amps at 12.8v anyway, people who want a pretty good ~7 inch plug and play speed control fan should consider the SS Fm181 and the more powerful Silverstone AP182. the issue is acquiring/fabricating fingerguards if exposed to fingers.

My sub 3$ 150 watt step up/ boost converter got some attention today, mainly removing the tiny 10K potentiometer that required a jeweler's screwdriver to adjust output voltage, soldering wires to the new holes in circuit board and using a 3/4 turn 10k ohm potentiometer. I previously used a plastic enclosure that was some sort of inline power supply for some forgotten device to house it, and simply tacked a voltmeter atop. I am making this voltmeter a bit more streamlined to the enclosure. I had noticed when charging the 24v nicad battery the voltmeter was more than 1v off at 25volts reading low, and I saw today there are tiny calibration pots on the voltmeters underside which I had forgotten about. This particular voltmeter was also intended to be an ammeter, but I have no shunt for it and the display would always read 00.0A and still will. I'll use one of my portable wattmeters on the output if I need to see amperage.

I went to go remove the tiny voltage trim Pot on my Drok 5 amp buck/boost step up/step down converter, but found it was a 50k ohm potentiometer, not a 10k, or 1K, or 100K, all of which I have extra's of. So while I have it apart, I used some amazing goop to glue the toroid and capacitors to the circuit board, as this buck boost converter might get attached to the 24v E-papst fan body, and the vibrations would eventually fracture the solder joints on these items.

So I am shopping for 50k ohm potentiometers and checking what other resistance value pots I might need for other boosters or buckers I will also be soon purchasing. 10k 20k 50k and 100K seem to be the main resistance potentiometers used on these.

I might be getting an 1800 watt voltage booster too. I believe one of these could 'perhaps' be used to boost a ~13.6v engine battery when driving voltage, to 14.8v for feeding a depleted house battery. 40 amp limit. I want to see what it can do. Renogy is selling a 20 and 40 amp DC to DC boost converter for doing this for 200$, but perhaps this 25$ item can do the same thing, without the fancy enclosure. The 24v hedge clipper might need to be powered by my 12v 18AH battery too. not sure a 400 or 600 watt one would be enough so why not go for the biggest step up converter offered?

I just got some acrylic glue. Might be making my own electronics enclosures from plexiglass/acrylic.