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
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