Yeah, RPi was one of my first thoughts. Maybe interface via WiFi to html graph,
Sent from my iPhone > On Sep 19, 2019, at 8:53 PM, Forrest Christian (List Account) > <[email protected]> wrote: > > So the upcoming base Base 3 will have that functionality at some point > (hardware is there, software not yet)... but.... > > There are also lots of DMM's out there which have a SD card or USB stick > which you can log to. > > For example, see page 48 in this document > https://www.eevblog.com/files/EEVblog-121GW-Manual.pdf > I also have a HMC8012 on my bench (not that inexpensive), but it does both > current and voltage simultaneously, and can log indefinitely to a USB stick. > > If you want to go the cheap route, I'd probably just grab a raspberry Pi and > an appropriate ADC hat. Or an arduino using the built in ADC (if there's > enough resolution) and a SD card shield. > > Alternatively, there are standalone dataloggers out there, for instance: > https://www.dataq.com/products/lascar/el-usb/el-usb-3-data-logger.html , > with varying precision, amounts of storage, voltage ranges, etc. > > > > > > >> On Thu, Sep 19, 2019 at 8:32 PM Chuck McCown <[email protected]> wrote: >> Constant current loads are easy. Like to have a data logger that does not >> need to be connected to a pc. I can download the logs, make graphs etc. >> but I might want the graphs to appear on the logger. >> >> Sent from my iPhone >> >>> On Sep 19, 2019, at 8:12 PM, Forrest Christian (List Account) >>> <[email protected]> wrote: >>> >>> If you can make a *constant current* load, then it's as simple as graphing >>> voltage over time, and probably adding a low-voltage cutoff at the >>> appropriate voltage. If you take the measurements at a regular interval, >>> then you can also apply math to come up with a reasonable version of power >>> in addition to load. Lots of voltmeters have PC based loggers. >>> >>> The advantages of all of the loads I linked to are that they're well >>> designed constant current loads. As to the advanced software from West >>> Mountain radio, that probably isn't needed. What I was referring to was >>> the $1K per 1000 watts of load cell once you get above 150W, but compared >>> to a brand new dc load at those same wattages it isn't all that pricey. >>> >>>> On Thu, Sep 19, 2019 at 8:03 PM Chuck McCown <[email protected]> wrote: >>>> I can make the loads. I like Mtn west but they want too much for the >>>> advanced version of the software. >>>> >>>> Sent from my iPhone >>>> >>>>> On Sep 19, 2019, at 6:01 PM, Forrest Christian (List Account) >>>>> <[email protected]> wrote: >>>>> >>>>> The west mountain radio CBA IV can't really be beat for price and >>>>> functionality. >>>>> >>>>> For around $200, you get a little USB-attached unit which can discharge >>>>> up to the lower of 150W or 40A, at a constant current. So you can set >>>>> the discharge to the 20 hour rate for a battery, and an app on the PC >>>>> will will log and graph. For newer batteries, this almost always >>>>> matches pretty well with the datasheet voltage. I use this fairly >>>>> regularly to verify the smaller batteries I have around. If you stick >>>>> with the 20 hour rate @ 12V, you're good up to around 250AH (250AH at the >>>>> 20hour rate = 12.5A/150W). >>>>> >>>>> If you're looking at an entire array you're probably going to need more >>>>> power - they have add on 'amplifiers' but they aren't cheap. Another >>>>> option is to go get a real DC load with appropriate software. See >>>>> https://www.youtube.com/watch?v=8y7mFXD8wII for an example. The rigol >>>>> illustrated is good up to 350W, other manufacturers have pretty much any >>>>> size you want, if you can afford it. There are also usually a few >>>>> floating around ebay of older types, if you can find or write suitable >>>>> software (i.e. write a python script to pull the data out at regular >>>>> intervals). >>>>> >>>>>> On Thu, Sep 19, 2019 at 7:32 AM Chuck McCown <[email protected]> wrote: >>>>>> Discharge and logging. >>>>>> >>>>>> Sent from my iPhone >>>>>> >>>>>>> On Sep 18, 2019, at 7:12 PM, Forrest Christian (List Account) >>>>>>> <[email protected]> wrote: >>>>>>> >>>>>>> Are you talking about doing a discharge test on a battery and logging >>>>>>> it? (Aka West Mountain Radio CBA IV, or the output from any of several >>>>>>> DC loads w/data ports) >>>>>>> >>>>>>> Or are you looking for current in/out graphing over a long period of >>>>>>> time on a system? This is pretty common and I *do* have solutions for >>>>>>> this. >>>>>>> >>>>>>> Or battery state of charge measurement? A victron BMV-700 series, or a >>>>>>> trimetric battery monitor /w some sort of logging? >>>>>>> >>>>>>> Or...? >>>>>>> >>>>>>> Also, if this is monitoring a live system, what are you charging it >>>>>>> with and does it have a data port on it? >>>>>>> >>>>>>>> On Tue, Sep 17, 2019 at 7:35 AM Chuck McCown <[email protected]> wrote: >>>>>>>> Just graphical discharge records. >>>>>>>> >>>>>>>> Sent from my iPhone >>>>>>>> >>>>>>>>> On Sep 17, 2019, at 4:33 AM, Forrest Christian (List Account) >>>>>>>>> <[email protected]> wrote: >>>>>>>>> >>>>>>>>> Nope, never got around to it. >>>>>>>>> >>>>>>>>> I've recently become aware of several products which do something >>>>>>>>> similar to what I had in mind. What were you looking for? >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>> On Mon, Sep 16, 2019 at 5:09 PM Chuck McCown <[email protected]> wrote: >>>>>>>>>> Did you ever build that battery tester characterizer thingy? >>>>>>>>>> -- >>>>>>>>>> AF mailing list >>>>>>>>>> [email protected] >>>>>>>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>>>>>>> >>>>>>>>> >>>>>>>>> -- >>>>>>>>> - Forrest >>>>>>>>> -- >>>>>>>>> AF mailing list >>>>>>>>> [email protected] >>>>>>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>>>>>> -- >>>>>>>> AF mailing list >>>>>>>> [email protected] >>>>>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> - Forrest >>>>>>> -- >>>>>>> AF mailing list >>>>>>> [email protected] >>>>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>>>> -- >>>>>> AF mailing list >>>>>> [email protected] >>>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>>> >>>>> >>>>> -- >>>>> - Forrest >>>>> -- >>>>> AF mailing list >>>>> [email protected] >>>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> -- >>>> AF mailing list >>>> [email protected] >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>> >>> >>> -- >>> - Forrest >>> -- >>> AF mailing list >>> [email protected] >>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> -- >> AF mailing list >> [email protected] >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > -- > - Forrest > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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