EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Dave92F1 on October 21, 2023, 05:24:54 pm
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I picked up one of these from AliExpress; the version with the display stacked above the MOSFET board and fan (see 1st photo).
It seems a useful gadget - I was able to easily measure the capacity of some 18650 batteries and max current supplied by USB power bricks.
But the documentation is...spare. Here are the modes it seems to have:
- CC - Constant current load (amps)
- CV - Constant voltage load (volts)
- CP - Constant power load (watts)
- CR - Constant resistance load (ohms)
For each of those, you set the constant parameter, and can (if you want) set cut-off times, voltages, or temps, and it'll create a report with terminal voltage, energy (watt hours), capacity (mAh), and time ("timming"!).
They're very handy not just as lab bench load modes, but to measure battery capacity.
Then there are what appear to be automatic test modes (see 2nd attached pic from manual); I've only figured out one of them:
- PT - Power Test? Performance Test? This gradually increases the current load and watches for a voltage drop. It prints out a report of how much current and power it was able to pull from the source before the target voltage drop is reached. Very handy for finding out how much power a power supply can really deliver.
- BRT - A similar automatic test, it says "DCload step-down type battery ttermal resistance testing" (sic; I assume "ttermal" is meant to be "thermal").
Anybody know what BRT mode is for? Output is "tenairesistance" (sp?) in mR, at various currents. What's a mR? What is this useful for?
- CT - Cable test? Says "Wire resistance and urrent performance detector" (again, sic and I assume they mean "current")
Anybody know what CT mode does (again, see 2nd image - bottom right)?
Last - in the setup menu there's "Over-Ex.Temp" and "Over-Bo.Temp" (see 3rd photo). Neither is mentioned in the manual, altho the manual does mention "Over-Temp" (which isn't there on my unit).
Anybody know what "Over-Ex.Temp" and "Over-Bo.Temp" are or do?
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Here's the manual I have, such as it is (attached). I haven't even tried the Bluetooth stuff (nor do I plan to).
I don't understand why people who make this stuff don't ever seem to use spell-checkers.
They could also ask ChatGTP, for free, if what they've written makes any sense in English.
Somehow they don't, tho. Overconfidence in their English, or do they just not care? I don't know.
(I assume the Chinese version is clearer. I'd rather have that; I suspect a machine translation of that would be clearer than what they wrote in English.)
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Just guessing... based on my recent relatively deep dive into the subject: I suspect BRT implements a form of DC IR (Internal Resistance) test, based on difference between two load steps.
The UL standard specifies use of a 0.2C load followed by 1.0C load, at specific time frames and SOC (State Of Charge.)
Somewhere around here I have a published scientific paper on the topic...