60W Electronic Load in 2022 - Page 1
Forum section: electronics / testgear

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 05, 2022, 11:37:42 pm
content: Has anyone recently bought a 60W Electronic Load that is calibrated ?Like the attached model on the picture.I bought one from Amazon, but it was off by 20mA. Then I ordered a replacement and the same, it was off by about 20mA.Long time ago I bought one that was spot on.Please let me know if you got a good one and from where and if you were able to confirm it's calibration was good.David DLC

author: janoc
author_rank: Super Contributor
timestamp: December 05, 2022, 11:58:39 pm
content: You want calibration (I guess you mean accuracy?) on a 20€ device??And why do you even need this gizmo to be that accurate? That thing has a specified accuracy 0.7% - 0.01A - 10mA, with minimum current being 20mA.So given how "optimistic" these "specs" tend to be (and how cheaply designed these loads are in general) I would say your 20mA error is totally in line with what the device is designed to do. Also, don't try to actually use it for 60W, it will almost certainly blow that FET.If you need more accuracy then either put a multimeter in series to adjust it - or you need to spend quite a bit more dosh on a more sophisticated load.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 06, 2022, 12:00:25 am
content: "Long time ago I bought one that was spot on."

author: thm_w
author_rank: Super Contributor
timestamp: December 06, 2022, 12:08:35 am
content: Quote from: DavidDLC on December 06, 2022, 12:00:25 amRandom luck.If you don't have the money, reverse engineer the circuit and figure out if you can put a pot in somewhere to tweak the value.If you have a few more dollars get one of these:https://www.eevblog.com/forum/testgear/cheezeball-dc-load-dl24p-pump-or-dump/If you want an actually trusted calibration, buy a load from a major manufacturer, which will likely be $300+

author: alm
author_rank: Super Contributor
timestamp: December 06, 2022, 12:11:09 am
content: Quote from: DavidDLC on December 05, 2022, 11:37:42 pmA calibration is a documented comparison to a traceable standard. So if you had a DMM with a traceable calibration, compared its reading to the load, and wrote up a document about how you did the comparison, then that might be considered a (non-traceable) calibration. Companies like Fluke do that for a fee, but that fee will be much more than the €20 you apparently pay for the load. So asking for a calibrated €20 load is asking a lot.What are the specifications for the load? Maybe 20 mA is offset is within specification? Does it allow adjustment? Then my suggestion would be to adjust it to whatever standard you have.If the device doesn't allow adjustment, then it's likely just a lottery what offset you get. Try ordering from a different seller, maybe you'll get one that has -20 mA offset, and you can hook two up in parallel for a net zero current

author: ledtester
author_rank: Super Contributor
timestamp: December 06, 2022, 12:19:17 am
content: I have one and my recollection is that you can calibrate it, but I might be wrong.In any case, you'll find more reviews/discussion about it using the search term "ZPB30A1".I haven't used mine in a while, but I remember it being pretty accurate. One can always do some tests to check the linearity and use that to correct the results. Another option is to replace the MCU and program this open-source firmware:https://github.com/ArduinoHannover/ZPB30A1_Firmware

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 06, 2022, 12:27:27 am
content: I have the money to buy a very expensive one, I just don't have a business reason to do it.I mentioned I got one that was spot on, maybe it was calibrated, maybe not. Now calibration does not necessary mean you need to get a certificate.I don't want to be dis-respectful to anybody but if you don't have any positive comments just don't waste the time here. I didn't make this post for entertainment, I'm looking for help hereWhen I get a notification on my email with a response to this comment, I'm hoping to get help, I'm not hoping to get sarcastic commentsI want to know if somebody has got one recently that is spot on, or know how to adjust this model. If you have a good comment on this please do soDavid DLC

author: thm_w
author_rank: Super Contributor
timestamp: December 06, 2022, 12:50:09 am
content: If you don't have the time to screw around with cheap tools for your business, then don't buy them.Various valid answers were given already, and they will take time and effort on your part.voltlog has even drawn up the schematic:https://www.voltlog.com/voltlog-39-60w-dummy-load-reverse-engineering/

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 06, 2022, 12:54:27 am
content: Quote from: DavidDLC on December 06, 2022, 12:27:27 amwhich one earlier posts is sarcarstic? if you think $20 is worth the hardware and traceable calibration included and all the works involved, then you are making an insult to the manufacturer... and anyone here with experience.

author: macboy
author_rank: Super Contributor
timestamp: December 06, 2022, 01:48:36 am
content: Quote from: Mechatrommer on December 06, 2022, 12:54:27 amThe one by janoc, and yours.In a specific context, "calibration" means verified against a traceable standard. This is very clearly not that context. In this context, the OP very clearly used calibrated meaning adjusted to be accurate. Very clearly. To anyone. Even you.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 06, 2022, 02:24:10 am
content: When I got mine, I got it because a review somebody did on it, the person mentioned it was very accurate. Then I got mine and yes it was very accurate. Unfortunately I cannot find that review anymore. Another person posted here that his was also, so somehow these units were adjusted/calibrated (maybe I should not use the word calibrated). Let's use adjusted from now on."If you don't have the time to screw around with cheap tools for your business, then don't buy them." I never mentioned I don't have time, I just don't like when people post comments that not help with the topic. I mentioned I don't have a business case to get an expensive one, and my comment is pretty valid. I can deal with cheap tools and I have time to get one.There is nothing wrong with me trying to get this little tool that fits my purpose. Even if it is $20.00. Now if I don't get one I already have a plan, but still can look for recommendations.I know still people will post negative comments after this, instead of doing that, try to help. My question was very specific:If you lately bought this model and it is accurate let me know.If you have not, try not to respond. How hard is this ?David DLC

author: janoc
author_rank: Super Contributor
timestamp: December 06, 2022, 08:44:51 pm
content: Quote from: macboy on December 06, 2022, 01:48:36 amAnd before you lecture someone on sarcasm I suggest you actually read what I wrote. I have clearly indicated/asked the OP whether they didn't mean accuracy instead of calibration, so that point wasn't lost on me.However, the rest still stands. If someone expects any sort of accuracy from such cheap device where you get whatever parts were left over this week in Shenzen, I don't know what to say to that. There are no precision components in that, so that large tolerances and offsets are to be expected as is drift with temperature. The OP never said how was that 20mA offset measured, at what load, how hot the thing got (esp. the Zener diode which seems to be the only reference there). And if they really do need it to be that accurate, it shouldn't difficult to adjust some of the resistors on the opamp measuring the voltage drop on the shunt to bring it in spec. Even though I am not sure why anyone would need/want to do that given that it is practically guaranteed it will drift again pretty soon.

author: tunk
author_rank: Super Contributor
timestamp: December 06, 2022, 10:37:05 pm
content: See if the main PCB says "ZHIYU ZPB30A1". If not, then you may havea lower quality clone. Is the offset constant through the current range?If not, then you may be able to adjust it:- if showing too high current, file a little bit off the shunt.- if too much, add a bit of solder.Review by member HJK:https://lygte-info.dk/review/Review%20Electronic%20load%2060W%20UK.html

author: BillyO
author_rank: Super Contributor
timestamp: December 06, 2022, 11:12:23 pm
content: You really do not have to have it "adjusted' to perfection for it to be calibrated. You just need to document it's differences WRT to something of known accuracy.Go buy one of these, get a hold of the good DMM that is known to be accurate (a recent "calibration to standards" certificate) then document any errors over the range it will be used. Your document is now the calibration for your load even if it cannot be adjusted to match.For example, if it is off by 20% high throughout the range of interest, then all you need to do is adjust it's readings by (100/120)=0.8333333 to get accurate results.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 07, 2022, 03:02:43 am
content: Quote from: macboy on December 06, 2022, 01:48:36 amif trying to explain the situation the OP is not aware of is being sarcastic, your post is also sarcastic... let me explain what you are not aware of... politely... traceable calibration was first mentioned here by alm, so is he being sarcastic too?.. and thats what understood by most technical person... and OP clearly mentioned calibration, not accuracy. but then both are related, to make one device accurate, you have to compare with another more accurate device, thats what we call calibration and tracability. and we are not aware of cheap device to make another device calibrated (properly according to eevblog community's norm). ask OP what he is using to comfirm his $20 dummy load is off? so i guess you have sort of attention disorder, or a disorder where people only want to hear what they want to hear, truth is not one of it... congratulation you are now one of people in my "most honorable" list (if you really can feel me of what being sarcastic)

author: baldurn
author_rank: Regular Contributor
timestamp: December 07, 2022, 01:50:02 pm
content: I did an experiment with my own humble setup. Mostly because I was curious but also to show that the OP really needs to specify what is meant by "spot on". The Siglent in the picture has a valid calibration certificate. The two Korad are apparently in agreement (measuring 0.048A) yet it is the Siglent that is most correct (measuring 0.049649A). If I program the electronic load for 52 mA you might think it to be "spot on" for 50 mA since both the load and the power supply would measure 50 mA. But it would be wrong. You need the calibration certificate to trust the measurement.I am not sure why my Korad KEL103 does not correct itself since it is programmed for 0.050A but measures 0.048A - should it not try to sink an extra 0.002A to hit the target? Lucky it is actually much closer to the target than what it measures.I know OP said he only wants or needs to spend $20 but really something like this Korad KEL103 is not very expensive ($360). How much is your time to try fixing the other cheap solution? I am assuming a few mA off is ok otherwise you need to pay even more money to get something that is certified. Or just measure it like I did and then perhaps correct for any error.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 10, 2022, 04:43:30 am
content: I found what I was looking for. I got an accurate enough 60 W Electronic Load.I took pictures with my portable power supply only, results from my bench power supply shows the same.The voltage is also very accurate, I measured it with my EEVBlog 121GW DMM, my Fluke 287 and my bench multimeter and all of them are similarNo need for support anymore.David DLC

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 10, 2022, 05:16:06 am
content: It also matches close enough to the little USB meter. Again I don't need more sophisticated equipment for this.Thanks to everybodyDavid DLC

author: vk3em
author_rank: Contributor
timestamp: February 15, 2023, 07:01:56 am
content: Hi David,I am looking for one of these as well. Just to do some simple SLA Battery Capacity and Health tests. Where did you buy yours from?ThanksLuke