DMM that has DC Watts - Page 1
Forum section: electronics / testgear

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 02:48:15 am
content: I've searched for hours for a DMM that can also display DC Watts (with the other usual functions).0-10A range / 0-400VDC. I haven't got the time to make a converter and I can't believe there's nothing out there!Anyone seen one?

author: staxquad
author_rank: Frequent Contributor
timestamp: July 28, 2013, 03:16:31 am
content: Quote from: digsys on July 28, 2013, 02:48:15 amHameg HM8115-2HM8115-28 kW Power MeterWide Measurement Range 1 mW…8 kWVoltage Range 100 mV…500 V, Current Range 1 mA…16 AFrequency RangeDC…1 kHzSimultaneous Display of Voltage, Current and PowerDisplay of apparent, active and reactive PowerPower Factor DisplayAutoranging for simple OperationMonitor Output (BNC) representing the instantaneous PowerSuitable for Measurements on Frequency ConvertersSoftware for Remote Control and Data Acquisition includedGalvanically isolated USB/RS-232 Dual-Interface, optional IEEE-488 (GPIB)

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 03:32:47 am
content: Yep, plenty of AC Power meters, like that one, but no DC Power meters. (Unless I missed something in the specs??)

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: July 28, 2013, 03:35:35 am
content: https://www.eevblog.com/forum/testgear/why-can't-a-multimeter-do-current-and-voltage/msg228518/#msg228518It doesn't calculate the wattage for you, but it does measure V and A at the same time.

author: Unknown
author_rank: Unknown
timestamp: July 28, 2013, 03:36:35 am
content: The specs state AC+DC, where do you get the impression that it's AC only? Some DMMs like the Gossen Metrahit Energy will probably also be able to do what you want. I'm sure there are other options out there.

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 03:47:14 am
content: Quote from: almWhere it says 20Hz-400Hz and 20Hz-1KHz, and power factor, reactive power etc ... all AC termsI'll be monitoring 4 channels live and don't have time to run calculations - seems such a simple addition.

author: staxquad
author_rank: Frequent Contributor
timestamp: July 28, 2013, 03:51:16 am
content: Quote from: alm on July 28, 2013, 03:36:35 amhttps://www.youtube.com/watch?v=uT4hKd66UY4#at=20

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 04:07:18 am
content: Bingo .. now to find a local seller linked to EEVBlog. ThanksEdit: OOPS, over $1K ea x4 .. bummer

author: IanB
author_rank: Super Contributor
timestamp: July 28, 2013, 04:39:39 am
content: Quote from: digsys on July 28, 2013, 03:32:47 amIn the specs, under "Active Power measurement", it says "Accuracy (20Hz-1kHz; DC)". That implies to me that it displays active power for DC measurements as well as AC measurements.

author: quarks
author_rank: Frequent Contributor
timestamp: July 28, 2013, 06:40:49 am
content: Before I bought my MetraHit Energy, I had a look at Metrix MTX 3282https://www.eevblog.com/forum/testgear/review-teaser-metrix-mtx3282-graphical-digital-multimeter/msg104803/#msg104803Because it is not clear what you need this for, there might be more options:- If want to measure at higher amperage only (1-10 A) also look for AC/DC power clamp meters.- If want to measure at lower DCV only (<60 V) maybe someting like a "Watt's Up" RC Watt Meter & Power Analyzer is ok

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: July 28, 2013, 07:22:20 am
content: Quote from: quarks on July 28, 2013, 06:40:49 am

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 08:55:23 am
content: quarks / ilove / et alI didn't expect this to be so difficult, which is why I left out important specs. I need 200VDC at least, and up to 10A.Next week I need to compare and profile a few MPPT controllers against a new one a club member has developed.This battery pack can get to 180VDC. The test has to be live and real-time for the "real" comparison to be valid.There are 2 listed in this thread that will be fine, but I need up to 6 and NOT spending $1K+ each.I have several 12 channel - isolated power designs in progress but won't be ready for a few weeks.I figured there HAD to be a DMM that, already doing DCV and DCA, could easily also do DCW. Guess not under $1K

author: IanB
author_rank: Super Contributor
timestamp: July 28, 2013, 09:02:12 am
content: I guess you need two channels to measure voltage and current simultaneously, and a two channel meter is always going to be rare compared to a single channel meter.But it did prompt a thought--does anyone make a modular design of bench meter where you can connect two or more of them together on a virtual "bus" or "backplane" and have them work as a single unit? One could be the master and could control the others while also collecting data from them to perform combined math or statistics functions. It should be relatively easy these days with network interfaces?

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 09:12:12 am
content: Quote from: PippyI work high HV / H-Energy Lithium packs all the time, but I'm NOT complacent. Our next pack will be 15KW, and doing thefinishing touches on my 3rd generation programmable 15KW electronic load - it's going to be FIERCE ! :-)Then I have to think about adapting for another teams pack at 400-450VDC, that will make me sweat a bit !!

author: TopLoser
author_rank: Unknown
timestamp: July 28, 2013, 09:14:50 am
content: I've got at least 4 of those Hameg HM8115-2 power meters I'd love to sell. They do DC power measurement in the range you specified. They are boxed, customer returns just refurbished by Hameg. Maybe £200 each?

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 09:15:16 am
content: Quote from: PippyI'd need 8-12 meters .. plus write software .. for a 1-off .. naaaQuote from: PippyI have a few 12 channel isolated designs nearly ready, but I need this next weekend, and don't have much free time.

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 09:20:14 am
content: Quote from: TopLoser on July 28, 2013, 09:14:50 amThanks for the offer, but it's only for a short term problem, plus I'm in OZ and I need them by Friday.I thought - surely there's a DMM (that are always handy anyway) that had V x I option.

author: quarks
author_rank: Frequent Contributor
timestamp: July 28, 2013, 09:25:24 am
content: Quote from: digsys on July 28, 2013, 08:55:23 amWith such a battery pack the 10A limit seems very low. Be aware that These packs can easily deliver hundreds of amps!I would definitely look for AC/DC power clamp meters. With these you should have a very robust tool and the advantage of not breakin the circuit for DCA measurement.

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 09:44:52 am
content: Quote from: quarksThanks, I'm very familiar with EV design and have tested scenarios at 300VDC up to 750A. The MPPT side is only MAX 6Aper channel, with secondary on the battery side.

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2013, 10:49:30 am
content: Quote from: digsys on July 28, 2013, 09:12:12 ampictures please, lemmie guess direct watercooling?

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 12:35:50 pm
content: Quote from: M. AndrásDefinitely avoiding that. The unit show has been up to 1.5KW continuous, 2.5KW peak. I am still playing with copperbus-bars and more air to get higher wattage, plus I need it to manage a 30KW 1-2S peak. Tests look good so far.I will definitely be needing to gang 4-6 of these together (less the better), the Network makes that easy.Paul Hogan: You call that a knife !?

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2013, 12:42:24 pm
content: hmm are those delta fans?, can you share the heatsink details?. i played with the idea of a high power load. but i made a 3model for a nice watercooled copper heatsink with approx 25celsius water input it can sink up to 2.5kw with a maximum surface themp on the sot 227 fets around 36celsius around 2-3m3/hour waterflow i had in mind with laing d5 pumps best i could find for this purpose

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 01:24:44 pm
content: Quote from: M. AndrásThe fans aren't anything special at this point. I expect the suction fan to literally catch fire at these power levels.I can then decide on a better replacement. The heatsinks are a custom extrusion, we had a couple palletslying around. They are damn heavy with very thick fins. I believe I'll need to create turbulence inside the cavity, soas to create a positive pressure. I'm going to need all the tricks.Quote from: M. AndrásThat's pretty damn nice specs. My rig sit at near 85-95C, with 105-110C at the very face of the BJTsWith all the HV lithium all around, there's NO way I can use ANY liquid, plus it has to be very transportable.

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2013, 01:31:16 pm
content: ugly as hell but if you are intrested i can mail you a shot from the simulation results from 1 of the variation, i must confess its designed with a free version of solidworks which i never used before without any machining knowledge apart from common sense, couldnt simulate the performance of the radiator i designed for this cos the damn program hangd around 2 days before said destination drive is full and all data is lost due to this. and i cant run the computer in summer at full power for 2 days cos everything runs over 50 celius on idle hell yeah 35celsius room temps..... when i finally get money to give out the files to machine out of a large 2cm tichk copper sheet i can test it in real conditions

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 01:47:58 pm
content: Quote from: M. AndrásSure, always like looks at other peoples designs / work.As for the rest ... LOL. You working in a prison in some far off desert? I'll never complain about conditions here again ! :-)

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2013, 01:58:16 pm
content: nah its my home lol, outside in sunshine approx 50 celsius today.edit: doh you cant send attachment in private massages?

author: digsys
author_rank: Unknown
timestamp: July 28, 2013, 02:33:34 pm
content: Quote from: M. AndrásYeah, I found that out too. Just use my email

author: Electro Fan
author_rank: Super Contributor
timestamp: July 28, 2013, 09:40:10 pm
content: Quote from: TopLoser on July 28, 2013, 09:14:50 amThe HM115-2 looks nice.3 questions, please/thanks:1. Just to confirm, this is the model:http://www.farnell.com/datasheets/493586.pdfSpecs:1mW - 8kW100mV - 500V1mA - 16AFrequency DC - 1kHzsimultaneous voltage, current, and power display (just missing resistance?)2. Just curious, why do you have 4 of them? Are you a dealer/distributor?3. Seem like handy devices; any reason we don't hear about them more often?Thanks

author: M. András
author_rank: Super Contributor
timestamp: July 29, 2013, 07:15:11 pm
content: btw digsys i sent you the files

author: DaveW
author_rank: Frequent Contributor
timestamp: July 29, 2013, 09:03:09 pm
content: Quote from: Electro Fan on July 28, 2013, 09:40:10 pmI did a review of this a while back, it works very well for DC measurements. We've been using it on DC-DC converters and CC LED drivers,

author: TopLoser
author_rank: Unknown
timestamp: August 01, 2013, 03:06:44 pm
content: Quote from: Electro Fan on July 28, 2013, 09:40:10 pm1. Yes that's the one2. Customer returns just refurbished by Hameg, careless customers who blew the protection fuses. All boxed and with remainder of Hameg warranty. All look like new.3. Because they're expensive I suppose! Well if you buy them new they are ;-)Still got 3 left, quite small and light and I'll ship anywhere at cost.

author: PuterGeek
author_rank: Regular Contributor
timestamp: August 01, 2013, 04:38:15 pm
content: I'm late to the party but I did find this on eBay:http://www.ebay.com/itm/Digital-DC-Power-Watt-Volt-Amp-Meter-for-HHO-Car-Golf-/350294800608?pt=LH_DefaultDomain_0&hash=item518f3278e0Looks like it would do what you want with the right shunt. Maybe you can find them in Oz.

author: TopLoser
author_rank: Unknown
timestamp: August 04, 2013, 07:52:58 pm
content: Quote from: TopLoser on August 01, 2013, 03:06:44 pmOnly one left, get em while you can!