I like your attitude. Giving vendors a chance to make things right it’s always a good way to go in business.

As you know, water heater elements are purely resistive. That means that the only thing input voltage changes is the amount of power it can consume. At the $25 price point you are likely getting either 120vac or 240vac water heater elements that have been repackaged for lower DC voltages. If you can find a 5500 watt (common size) 120vac element, locally or online, it will put out roughly 600 watts from a 12.8v DC source. And it will likely be about half the price, as you save the middle man markup.

Thanks for the video Its looking forward to seeing the results and if the next ones are up to spec.

I appreciate your attitude towards the situation. Refreshing. Hopefully the next set work as advertised.

I appriciate how you handled that.

Thank you, sir.

Like that you are giving them another chance. Hope its as advertised this time

Testing to validate specs is always good - especially when dealing with Chinese stuff. Thanks for sharing your testing methodology - looking forward to your next project.

Thank you,I had the same problem!

heya totaly agree and that's why it's good to do your own test's and calcalations

I like Dave's attitude here giving small businesses a quote un quote " A Fair Shake ". 👍👍👏👏💯

Love your content so darn much man you rock honestly

I just got me some 12v 600w im going to test them like you are

Think you for the video

great video, thanks !

When you measure such a low resistance with a DMM, you need to zero out the resistance of the leads. The leads have more resistance than the element itself. A better bench type meter will allow you to make 4 wire measurements using 2 force leads (forcing current) and 2 sense leads (measuring voltage). However, your water bucket power test did seem to indicate that the element was weaker than expected and the wire gauge was pretty huge, so the poor result cannot be blamed on wire loss in that test. You were right to return them anyway.

Looking forward to the 600w video.

Thanks for the video! I'm in the process of setting up a 12v load diverter on my sailboat to heat water for showers and washing. Now I know that I might not get what I order and to double-check the resistance of the element before going to all the trouble of installing it. I=E/R "More than a good idea, it's the law" Best regards from Key West, Capt. Blackheart Charlie

...just wanted to let you know that my new 600W 12V heating element came in today. The resistance tested right (2.4 Ohms, although I know some resistive loads can change dramatically with temperature...this doesn't seem to), and when I connected it to my 12v 62A power source, I FINALLY GOT 50 a @ 600W. I got it through Amazon and it was a 'twin' for the fake. Thanks for the video!!!

We need more guys like you in society Dave. You and your family are awesome. Love the videos!

Great video!

Always with cool stuff 👍

David, a cold resistance measurement will give x. However the only way to know the resistance at operating temperature is a voltage and current measurement and calculate. All resistive conductor's resistance varies with temperature, most are positive and as temperature increases so does the resistance. At switch on there will be a surge current which drops off as the element heats up. One other point to remember is that multimeters are rubbish at measuring low resistance.

great content thanks

I see you actually verify what you purchase, and that IS a good thing. So many would have never ever done that. And that is because the typical consumer just doesn't understand such things... Thumbs Up! Math doesn't lie!

An Unintended Consequence - While watching this video I saw you measure a DC current with the meter clamp and wondered how that was possible. My experiences with clamp around ammeters years ago were limited to AC circuits where the varying flux induced a voltage in the clamp coil. So I used Google Search and, thanks to Fluke, learned about Hall Effect sensors for steady state flux measurement. Seventy-five years old and still learning stuff all the time.

You should use Kelvin contacts (4-wire) when measuring low resistance.

I ordered a 12V/300 watt element from them. I plan on putting it into a 18 gallon barrel inside a 30 gal barrel surrounded by closed foam insulation!!

The battery controller meter concured with the multimeter. Right there is the confirmation before going anywhere else. 1.1ohm suggests that the element is a higher voltage rating, which equals incorrect product sent.

Great use of tools to verify the specs! And great attitude about it. What is the ammeter box that you were using?

Wow, that is very poor of them to have sold a product they "just got in" and didn't do any testing on. I like your attitude towards giving them another chance, but I feel that wasn't a mistake... We shall see, keep us posted on how the new element works!

*Chinese watts are only 20 percent US watts*

I hooked up 2 full sized solar panels in series. Then wired them directly to the bottom heating element in my home hot water tank. I used the rated voltage and current of the panels to figure the panels resistance. Then found an element that was close to the same resistance. Heating elements do not care if the power is DC or AC or the voltage as long as the voltage is not too high. The top element made sure that the water was up to temp. Did not have any switches or controllers. Wen the sun was shining it heated the water. Wen the sun went down it did not heat the water. I used some big 50A plugs to connect the element to the panel wires. It worked really well in the summer. not as well in the winter.

I agree with the other poster. These sound like 1500 watt elements because 10 * 12 volts is 120 volts, and 10 times 150 watts is 1500 watts.

OOOOHH YEAEE EVERYTHING IS SO BEAUTIFUL

I enjoy your videos. I would like to see if you can run your heating element in a bucket to run your garage under floor heating.

I love your videos

When measuring low resistances, it is common for the meter leads to have higher resistance than the resistor. Low resistance is often measured with a "4 lead ohm meter" setup. Use a constant current lab supply and feed your load with 100mA or 1A depending on the load. Measure the voltage across the resistor and calculate the resistor value. EG, your element at 1 amp is close to 1 volt, so it would be 1 ohm, or if fed 100mA, would be 0.1 Volts = 1 ohm. With this method the real 800Watt element at 1 amp would have 0.18 Volts on the terminals and dissipate 0.18 watts, so the test would not heat your element for the test.

Great attitude, give them a second chance!! Nice! Congrats!

Hook up the elements in series then take a resistance reading. Meters like that do not do well near 1 ohms. If each element is 1 ohm in parallel they will be 0.5 ohms. in series 2 ohms. Your meter will give a much more accurate reading at 2 ohms.

I want hopefully we can get an update on the 600 watt heaters to see if they are as advertised

Max power point is when the resistance of the source equal the resistance of the load. Most heating elements increase resistance as they heat up. Old fashioned lightbulbs made of tungsten changes resistance dramatically. I don't know the temperature characteristics of these type of elements. I suspect they are made of tungsten and the resistance will increase as they get hot.

I'm pretty sure they sale the elements as maximum wattage. So if you apply 24v or 48v, you'll see more wattage

Low wattage elements will be slow but very useful in a solar-powered RV like mine.

So about 30 volts to get closer to the watts on that one. Seems like a lot of amps to try and eat power at 12v though.

Ive similar ones, they can be 24v 600w with 2 elements in series with or 2 x 300w in parallel - depending how the brass fitting on the end are configured - so watch out for that as mine came with the brass connections for parallel / 24v

Nice

I'm sure you checked the jumper plates on the fitting for correct connection.

They usually have the specs printed on them. I ordered a bunch off AliExpress straight from China for the DMPPT450 setup, and if you can wait a month for them to arrive, I can recommend going that route as they're significantly cheaper and were exactly what I ordered.

Thanks for this wonderful insight. Please I have a steam boiler of 24 liters and 3 phase, producing 6 bar pressure. Please what if I changed this connection to single phase, will I I still get 6 bar pressure? Thanks.

You could just get more of those and put them in parallel. At least if you have more of them the chances of them heating up will be less and as a result of the banks higher power handling they will have a steadier resistance.

i was looking at buying a 12vdc element recently and came across a website that explained possibly what is going on. Apparently is all too common practice for resellers to buy standard AC water heating elements and sell them as more expensive DC elements. Apparently all heating elements are marked for their voltage and output, dishonest sellers will melt these markings to make them illegible. Check your elements and look for the markings or the melt plastic which was used to cover their tracks.

Good

You have a heater whit 2 heaters in it. the copper plate in between wil put it in serie or parralel. I think it is on serie, so both heater wil get each 6V that means both heater are 0.5ohm each, if you change it to parralel than both heaters wil get 12V and the resistance is changed to 0.25ohm in theorie. Than the power draw changes to 800watt. The second question is than wil the unit be able to resive and hold the 67Amps or wil it melt because of the high current

Resistence varies with heat, if that is measured in cool 1.1ohm, in hot it will get higher resistence.

would work pretty good for a 24 volt setup at 500ish watts

Check your math at 48 volts. I think they sent you the wrong ones.

I'd be into a low wattage 24v dc thermostatic controlled one, like the 240v ac 3kw item found in my house. It'd make a useful dump load.

I'm noticing that it's getting more and more common to sell items bit off the listing. I assume that they will get a ton of money on customers not technical enough to notice it. But now 3 times I have encountered this, thay all seem to go the same route and try to buy you to be silent.

Before you said "we have been running for 10 minutes" I was gonna say "just wait until you let it sit for a bit... as a resistive load gets hotter the resistance increases so your power will decrease" lolol

getting into vlog a bit , what kind of camera set up are you using David?

would be best on 36V... old grid tied panels. 1R. 12v. 12A. 12x12=144 X1=144. yep. 150 watts. 36v/1R 36A. 1296W... theyre immersed. theyll take a bit more. plenty more... or you just ignore all of that and buy nichrome wire by the roll. what will glow red or melt in the air will stay cold in water. it doesnt need to be insulated, its still more conductive than the water.

Hi David. Great you make this public. Yes, good to give them another chance. On the other hand, they should test the products they sell! In this case its such a simple test, as you just demonstrated! There are so many 'cowboys' out there making false claims on what they are selling - great you are taking it to the public. Cheers

You were right because I’m at Mater it says 01.1 I think I trust your meter and that other meter more than I would eBay.

When measure low ohms 4 wire is best, or use current - voltage drop access the elements

You got a 24v 600w heater... at 12v it is only 150w... if you double the voltage the current doubles so you get 4 times the watts...

Hi David! Are you going to do some experimenting on the dmppt450? I'm waiting for that one!!

One thing to consider that has not yet been mentioned here is that power ratings for electric components are often a maximum. Meaning that exceeding that rating will likely damage or shorten the life of the component. The actual power dissipated (heat) will depend entirely on the voltage applied and the resistance of the element, which will change a bit (increase) as it heats up... Yes, the vendor likely sent Dave the wrong element, and the resistance should be specified by the seller.

What problems would I have connecting 600 watts of solar directly to a 600w 12v heating element in heat storage tank besides the possibility of overheating? Skip controllers, relays, or thermostats.

I am vaguely remembering something I encountered decades ago and haven't used since, fair warning. One of the tricks with transferring power is impedance matching. The resistance of the current source must equal the resistance of the load. Since you can't put an ohmmeter across a battery or solar panel, you look at its short circuit amps, and derive the resistance from that and the voltage. In essence, this is the same trick you use in a mechanical power train by shifting gears. Something to think about; I'm up late and can't be arsed to suss out the details.

Just wondering what youre using to keep the heating ellement away from the bucket melting

The terminals look like they can be swapped between serial and parallel. Perhaps try it in the other configuration.

I have one of these to heat up an outside shower in my camper, it was advertised as 150w. I actually cheat a bit and run 24v through (cheap enough that if I burn it out, ill know not to) but have probably had it running all told for about 15 hours, and yes, this isnt to make a hot shower, just luke warm :)

Hi anyone know if it would be safe to wrap stainless steel pipe around an element? Trying to get a little bit more heat in my circulating shower

Hi David, in this country 🇬🇧 we call it not fit for purpose 😔 If its 12V elements 800W look for mobile home - camping gear that has internal elements of suitable power, then obtain parts list and order that part, 👍 To be honest elements should be stamped 1kw 2kw 3kw 800w etc Look at manufacturers that make only elements & if possible buy from them 👍 Or obtain their suppliers, Don't go for general suppliers that just buy in from China & double up the price, Buy from China or HK or Japan directly Philip D 🇬🇧

I understand that they can get things wrong, but a simple multimeter check at their end would have resulted in a better outcome for all who have ordered them and the company itself. Thanks for the heads up David.

Thx. Like # 770. Did they remove the ad from eBay?

Did you measure the voltage at the terminals to confirm that you were actually delivering 12V to the load? Your lead resistance may be part of the problem.

Good about the video! But, why someone has a wall panel tools that has so much hammers, instead diversified tools? Hehehe! You won a follower guy!

Can you use the same pv panels for the dc element and the inverter?

are the elements hooked in parallel or series series well be more resistance keep up the good work

I think they provided 120v 1500 watt elements instead.

Ahem. They are also as often listed in terms of current draw and N volts. You aren't really very interested in watts, you're interested in amps of current. It's even straightforward to translate volts / ohms / amps because they directly correlate to each other.

Your multimeter probably has a resolution of 0.1 ohm. As such, it's not best suited to sub-1 ohm measurements. When measuring low resistances, first 'calibrate' your measurements. Touch the probes together and note the reading. Subtract that number from all your measurements. Still... clearly the elements were not what you wanted.

were these sold as 800w electrical draw or 800w of heat output

An idea : what if you pass the water pipe, going to the tank or going out of the water tank, through a dc induction heater that works on solar panels? Will that give instant hot showering water maybe!?

What collar did you use to put that in the bucket?

Was wondering if the resistance decreases when heated as some materials change resistant with temperature? Just covering the bases. I came across the same similar issue here recently.

I was thinking them would be more like 48 volts. Thanks for sharing. God Bless.

Heard about you from will Prowse. Looking forward to watching all your videos. I just bought 9 x 230 watt 24 volt (used!) solar panels and now I’m trying to figure out how to put together an entire system-also buying all used components. Wondering if there is anything in particular I shouldn’t buy used. I have lots of thick copper wire from wiring a hot tub and and from wiring a kiln and also a couple of gfci’s. I never hear anyone talking about using gfci’s on solar systems. Is there a reason? Can I re-use these? Thanks. It seems from wills book I have 2070 watts in panels so I have to have a 2000 w inverter but thought maybe I should get a 3000 or would 2000 be okay? Also I think the mppt should be 85 amps...and the batteries I was going to make from scratch, but I don’t know how much battery to make except I think it has to be 24 volt batteries and I should get at a minimum 2 x 100 amp 12 volts and wire them in series but that maybe it would be more appropriate to make 4 x 100 amp 12 volts and then wire them in 2-in-series for 24 volts and put the 2 sets of two in parallel for 200 amp hours x 24 volts or a total energy storage of 4800 watt hours. Have I calculated this correctly? One thing I am not sure is: I could only get 9 of these panels. Is it okay to use all 9 or should I only use 8? Later I would like to add some wind, and I’m keen to experiment with wind driving a couple of small flywheels I scavenged. Is that crazy? And I wanted to use any dumps to heat water and my living space (will be off grid as I have to move my RV somewhere else by May 1st. Also - is it okay to have the temperature fluctuate for my lithium batteries from 50 F at night to 75 in the day? Thanks for your comments and suggestions

Is it likely to be a pure resistive load? Don't they have coils inside?

Hello David on water heater element which is the positive or negative terminal s please has I'm trying to make hot water

What are you using now for hot water since its been a few years on most of your testing? Im on solar except my hot water heater.

When I was working for ebay seller. He was writing Tested, assuring you that it it as advertised. But no one ever touched the item for testing because time is money. Not every buyer will notice, chance that flaw will not be discovered is high. When you read tested - mostly not tested.

How about measuring at temp

70Amps from a car battery long enough to heat a bucket of water sounds plausible to you? Will the battery survive?

Try both elements you said there are two in there in parallel

Can't get nothing past the Poz

I need some doubt please told for me

The resistance of the heating element will change dramatically as it warms up.