Choosing a DMM for energy harvesting - Page 1
Forum section: electronics / beginners

author: Plexter
author_rank: Contributor
timestamp: May 16, 2015, 10:12:56 am
content: Hi folks,I've been meaning to get serious with energy harvesting and also happen to look for a decent multimeter. I was considering Fluke 177 but it doesn't measure lower than 10 uA. Although pretty decent, I imagine I'd often be dealing with lower values. Brymen BM867 can measure as low as 10 nA which is great but I'm feeling a bit uneasy about Brymen even though I've seen them recommended on the forums here.BM867 is considerably cheaper than the 177 and my experience tells me you usually get what you pay for. I certainly don't mind paying less but would rather have a reliable meter. The thing that most bothers me about Brymen, however, is their website -http://brymen.com/product-html/cata860/Bm860L2.htmIt looks hastily built without too much concern which is ok for personal websites and scams but I see it as red flag when a company has invested in it.I had a look at Keysight (Agilent) DMMs but they don't seem to have a lower range than the 177, at least not the ones in the £200 ($300) price range.Do you guys think I the Fluke 177 will be good for the job or should I go with the BM867? I don't really have a lot of experience with energy harvesting so I'm just guessing I'd be dealing with lower than 10 uA values. Also, would you recommend a different DMM for the job?

author: wraper
author_rank: Unknown
timestamp: May 16, 2015, 10:29:27 am
content: Quote from: Plexter on May 16, 2015, 10:12:56 amYou should be more worried if what you are going to do is a scam. And what particularly you do mean by energy harvesting?

author: Plexter
author_rank: Contributor
timestamp: May 16, 2015, 10:48:57 am
content: Quote from: wraper on May 16, 2015, 10:29:27 amPersonal projects on this stage, starting with this kit -http://www.we-online.de/web/de/electronic_components/produkte_pb/demoboards/energy_harvesting/energy_harvesting.php.I don't intend to join the dark side of energy marketing if that's what you mean

author: TimFox
author_rank: Super Contributor
timestamp: May 16, 2015, 03:49:22 pm
content: If by "energy harvesting" you want to compare input power to output power of a device, in search of free energy, you must use proper AC techniques to measure true "mean power", averaging the time values of instantaneous voltage and current, not merely average absolute values of voltage and current.

author: free_electron
author_rank: Super Contributor
timestamp: May 16, 2015, 06:10:29 pm
content: at the power levels you are dealing with that meter better have a larger than 10 megaomh impedance in volt mode...10 megaohms on 10 volt is 1 microampere of pure loss due to the meter ...

author: Wytnucls
author_rank: Super Contributor
timestamp: May 16, 2015, 07:01:16 pm
content: A second-hand Gossen 28S sells for about 300$. it has a resolution of 1nA on DC with a 310,000 count.Accuracy: 0.05% + 0.02% of range + 5 on 300uA range. More than 20MOhm on 300mV range and 11MOhm on 3V range.http://www.ebay.de/itm/Gossen-Metrawatt-Multimeter-METRAHit-28S-wenig-genutzt-sehr-guter-Zustand-/281692393083?pt=LH_DefaultDomain_77&hash=item41962cce7b

author: Lightages
author_rank: Unknown
timestamp: May 16, 2015, 07:06:09 pm
content: I put a disclaimer in my signature for a reason. I do not want people to think that I am hiding my business ties with Brymen when opining on multimeters. To be clear, I purchased three Brymens before I became a distributor. I decided to became a distributor based on my experience with their products. They offer near the same quality as Fluke and they are the OEM for Extech, Amprobe, and some others. Greenlee re-brands Brymens with no change other than colors and give them a lifetime warranty. Their build quality is maybe second to Fluke and they have the highest safety ratings available, CATIV/1000V. This is also backed up by third party testing and all of their meters are UL tested and listed.The BM867s is an outstanding value and has features that even the Fluke 87V does not have at over three times the price in most cases. Flukes generally have a lifetime warranty and auto touch hold as features over the Brymens. Fluke also has a longer history and a well earned reputation from these years. I also own a Fluke and have used many over the years. It is hard to go wrong with a Fluke. Brymens cost less and offer more features and are still built very well.Obviously I am going to recommend you get the BM867s and I assure you will be happy. Make sure you get the "s" version which has the improved back light and meets the latest IEC specs for CAT ratings.

author: Lightages
author_rank: Unknown
timestamp: May 16, 2015, 07:10:10 pm
content: As a second option, consider looking for a used high end bench meter that will give you gig ohms impedance on some of the voltage ranges. I recently purchased a Keithley 197 that has 1Gohm input impedace up to 2 volt range and it only cost around $125USD. It is still within spec too.

author: Electro Fan
author_rank: Super Contributor
timestamp: May 16, 2015, 08:41:42 pm
content: Quote from: wraper on May 16, 2015, 10:29:27 amWe'll see what the OP says but I think the reference to Energy Harvesting might mean the ability to utilize otherwise unused energy to power some type of chip. Energy Harvesting is based on the concept that various technologies generate energy that currently is not captured but which could potentially be captured and put to good use. For example, an automobile generates a fair amount of mechanical vibrations which could potentially be captured ("harvested") for use in powering chips on board the vehicle. Escalators that people use to travel between floors in buildings could potentially be sources for energy harvesting. Likewise, sound, light, and other forms of energy could potentially be better harnessed (captured, stored, and transmitted) to power semiconductors that run on increasingly lower amounts of power. It is a path toward better energy conservation.I might be wrong but I think the OP is just looking for recommendations on DMMs that do well with measuring relatively low voltage and current.http://en.wikipedia.org/wiki/Energy_harvestingEnergy harvesting (also known as power harvesting or energy scavenging) is the process by which energy is derived from external sources (e.g. solar power, thermal energy, wind energy, salinity gradients, and kinetic energy), captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.Energy harvesters provide a very small amount of power for low-energy electronics. While the input fuel to some large-scale generation costs money (oil, coal, etc.), the energy source for energy harvesters is present as ambient background and is free. For example, temperature gradients exist from the operation of a combustion engine and in urban areas, there is a large amount of electromagnetic energy in the environment because of radio and television broadcasting.The history of energy harvesting dates back to the windmill and the waterwheel. People have searched for ways to store the energy from heat and vibrations for many decades. One driving force behind the search for new energy harvesting devices is the desire to power sensor networks and mobile devices without batteries. Energy harvesting is also motivated by a desire to address the issue of climate change and global warming.

author: Plexter
author_rank: Contributor
timestamp: June 11, 2015, 10:28:02 pm
content: Thanks for the suggestions, guys!