I just ordered a Victron BMV-700 to use as a battery monitor for a portable solar system. The 700 series added watt measurements, and I think it has optional hardware and software to log the data. These are used for larger power draws of course, and I'm not sure what the resolution is yet, but I thought I would throw it out there. Good video, you have a ton of toys!
Thought provoking. I suspect the more expensive devices have a higher sampling rate (or employ dual-slope convertors) in order to catch unruly spikes. Recall, from the video I did on decoupling caps, that some devices have a non-constant current draw. If your testing device samples at a low rate, it might miss those short current spikes, thereby not producing an accurate picture of total energy consumption.
Proyectos LED Yes...good point. It does have its limitations in terms of what I would like to do but I hope to show that in a future video. Thanks for the post.
Good video Martin. I'm looking forward to part 2 and 3. I just sent the Solar BMS to you about two hours ago. I will make sure to send you the tracking number also. The Solar BMS dose do Ah and Wh measurements with appropriate accuracy for such a device. Next project will hopefully be exactly what you are looking for. A data acquisition system with 8 differential channels or up to 16 single ended and a 24bit resolution witch will probably give me at least 6 to 6.5 digit. Not sure about the price at this pint but I'm targeting under 200$ possibly under 150$ including international shipping cost. It will do power and energy measurements that can be saved locally on SD card or remotely send with Bluetooth to a PC or smart-phone. There will also be multiple dedicate IO pins for automations that can be programmed as alarms for different ADC levels. Hopefully it will be more successful than the Solar BMS. That is probably the reason those DC energy measurement equipment are so expensive. Is do to low interest and low volume is such equipment.
Usually the voltage is named "U", same as the current is named "I". It doesn't make sense to mix it with the units V and A. So P=U*I, which means W=V*A, if you are using the units.
Thanks, that's interesting, didn't know we are so different. A quick search on Wikipedia shows that it is V for other European countries like France, as well. Sorry for the confusion. Nevertheless, U makes more sense for me, because you can't mix up the name and the unit, more consistent with I and A, or R and Ω.
+mjlorton Thanks for these videos Martin. I've been studying the manuals for the Metrahit Energy and Metrahit Ultra, preparing to order one or the other. The Energy appears to have more functions, but a question I have for you (if you choose to accept it) is, is there anything the Ultra can do that I will miss if I buy the Energy? So far I've not found anything (other than Bluetooth in the BT model), but I'll keep looking. Your clues will help. Thanks. :-) Rick.
It occurs to me Martin you have the basis for suitable device right there on the bench in the Maynuo DC load. Configured as it is it would cater for the battery testing but not as an inline device. I can imagine it would be possible for the manufacturers to utilise the basic V and A instrumentation to monitor energy in a pass through mode. Probably only unidirectionaly so not quite the total solution for solar installations. I recall Frankie initially turned you on to this device perhaps he could quiz them if a proposal such as this is possible. Frankly I am amazed the solar industry has not turned up such a device for the consumer market.
Rob B Hi Rob, You are correct and there are several other devices on my bench that with a simple firmware change could do both power and energy measurement...even if not in-line. I also don't understand why there is such a gap for both the solar and the electronics hobbyist consumer market. I've chatted to several American based companies who acknowledge the fact there is a gap in the market...but no one thus far has done anything about it. I bet a Chinese company eventually gets there first....Fluke...Agilent / Keysight...Keithley...Tektronix..need to get a move on....
Congratulations Martin ... Great content, and this will be a series I am interested in. But best of all, all of my complaints about the repetitive use of certain words was nowhere to be found. That really helps to keep your audience focused on the topic.
Interesting reviews coming up. You didn't mention the UNI-T UT71E for power measurement. It comes with a AC mains power measurement connector for up to 2500W ±(2%+5); max. 5A continuous. A DC connector you will have to make youself. I have measured power LED DC consumption with it (7W). It uses a shunt for higher power and it's accuracy is thus not very high for low current measurement. It an affordable "mid or high level" multimeter - that isn't too big for a small bench. Please give more info on the "penlite batteries with 20 year shelf life"!
There is another power meter you missed in your market survey, the Hameg (Rohde & Schwarz) HM8115-2, list price in Germany 568 €. It's only a power meter, not an energy meter and would require data logging to a PC (RS232/USB, optional GPIB) to calculate the energy.
leppie Thanks. If you have a look at this video it will show some devices for the home AC power measurement.How to Solar Power Your Home / House #6 - Monitoring devices to measure energy and save money
mjlorton Argghhh, those... :( Was hoping more similar to this: www.wattvision.com/ (waay too expensive IMO) (I have had a homebrew version of it running for year at home now, busy designing a new/better one for the flashing LED power meters we have here in South Africa, but I believe thet are quite common world-wide)
leppie Aaah, then consider looking at this: www.exsolar.co.za/products/monitoring-devices/advanced-energy-monitor-exsolar-em502/This was one of the best "consumer" devices I came across some years ago. I introduced the gent that developed it to Exsolar and they have improved the design since I last saw it.
