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Reviews (9)
13 Jan, 2017
Works, but controls are confusing at first.
5 of 5 found this helpful This device works as expected, but it takes a little while to get used to it. There is little documentation that I can find, so hopefully this will help you use it easier.
Connect your source to be tested to the green wire terminals, marked positive and negative with positive closest to heat sink. there is also that white plug but I'm not sure if it connects in parallel, serial, or is isolated from the green terminals, so be careful.
Connect power for the tester to operate to the barrel plug on the opposite side. The barrel connector takes a standard 5.5x2.1mm barrel plug which needs 12 volts, center post positive. I used a 12v 2A power adapter to power this, and it works fine. You can likely get away with much lower amps, so long as it is close to 12 volts.
the tester will turn on and spin the fan for a moment. Then the top display (closest to the heat sink) will show target voltage, and the lower display will show target amperage. Notice the green LEDs between the amps and volts display. These indicate which precision you are adjusting (tenths or hundredths). You turn the knob to adjust up or down, and click the knob in to change which value you are moving. Click through amps tenths, amps hundredths, volts tenths and volts hundredths (not necessarily in that order, mind you). When you are ready to test, click the red Run button to start/stop.
Now, there are two functions this unit can operate in. It took me some time to find this. Unplug power from the barrel connector, hold down the Run button, and plug in power. You can release the Run button now. You will see the display changed. Now, turning the knob will change which function you are in, as well as changing the beeper mode. try clicking around in there for a bit to see what all it can do. Once you find this "hidden" menu, it's pretty straightforward to use.
Function 1 seems to just place a constant load on the test source, and display source voltage. You can vary the load by turning the knob while the test runs, which is nice.
Function 2 actually counts up the amp hours and watt hours as the test runs. The green LEDs on the right of the upper display actually tells what value is being displayed, and it cycles through Volts (source), Ah (amp hours drawn cumulative), and Wh (what hours calculated cumulative).
When the tested senses a voltage at or below the cut-off voltage, it will stop in Function 2 and beep a lot. in function 1, I don't know if it actually stops, or just makes a bunch of noise, so watch out for that.
The accuracy seems to be quite good. I used 4 wire testing for voltage/current on a fixed resistor to calculate the capacity of my batteries, and this tester returns almost exactly the same number I calculated, but with MUCH less work. I'm confident my manual calculation was less accurate than this tester, since I only sampled every 60 seconds for 5 hours and hand entered values into Excel.
The max load this can handle is 60 Watts. So, if you are testing 12 volts, it won't allow you to enter more than 5 amps load. As the voltage goes down, the max amps you can set increases, and as the voltage goes up, the max amps decreases, of course. It gets a little warm, but it is dissipating the energy as heat, so that is to be expected. The fan does a good job, and is relatively quiet too. The max voltage you can safely connect to test is 30 Volts, and the max amps you can draw is 9.99 Amps (at 6 volts or lower).
For example, to test individual Lithium Ion cells in function 2, set the cutoff voltage to 2.5V (or 2.75V, whatever the manufacture of your battery recommends as minimum discharge voltage), set the amps to the capacity rating on the battery for 1C discharge rate (or whatever rate you want, but don't exceed manufacture recommended discharge current), and hit run. The tester cuts off at the voltage you specify.
I hope this has been helpful to someone like me who couldn't find good documentation for this.
31 Dec, 2016
Acceptable management circuit, but no charge current limiting.
TL;DR:
Warning! If your batteries a very sensitive to rapid discharge/charge, or you need to limit the maximum discharge/charge current for some reason, this circuit is NOT FOR YOU!
Full Review:
I have this charger connected to 6x samsung icr18650-28a batteries in 3S2P configuration. The circuit properly balances charge between the batteries, and cuts off (open circuit) when any cell (2 cells in parallel in my case) drops below ~2.85Volts. When charging, I provide 12.9 volts (notice that my cells are 4.3V charge rated), and it seems to charge up ok, though it gets a little warm (92F in a 72F room). The charger does NOT limit charge current, and when first starting out a charge, draws 7 amps (3.5 amps per cell for me, since they are in parallel). It drops down to 3.8 Amps within 2-3 minutes, and gradually falls off to 0.1 Amps over 3-4 hours. Eventually, it disconnects charge and draws no additional power. I was a little worried about the initial high current inrush at lowest 10% state of charge, as this is actually about 20% above the rated charge current for the cells. It quickly falls to within a safe current, and actually completes a saturation charge within 4 hours, so I've decided that is acceptable for my needs. I have closely monitored the charge process though 6 complete discharge and recharge cycles now to make sure it doesn't malfunction, and it seems to be working well. My cells are only rated for 5.2 Amps max discharge, and in parallel that means 10.4 Amps. I have not tried to draw more than this, so I have no idea if the circuit will actually arrest an excessive load. I suspect it will not, so be careful!
Advise for potential buyers: make sure you get a high enough current power supply to charge this greedy circuit, as it will attempt to draw excessive current if you use a lower rated power adapter. I'm using a 12V 10A power brick for mine. I use a 100 W boost converter to step up the 12V input to 12.9V. I also recommend that you provide some sort of current limiting device for charging using this circuit if your cells cannot handle large-ish charge currents, but I have not tested this to see if ripple current will confuse this charger. As always, TEST before deploying anything into production.
25 Jun, 2017
Appears to be a good battery pack, at a great price.
I have only been able to do cursory testing of the battery pack so far, but it appears to be of good quality. The mass of the pack indicates that these are not cheap knock-off or fraudulent cells. I would recommend them. I charged my packs up with a 42v 2A charger for a scooter, and it took 3 hours to charge, which is good, since that means that the cells do have considerable capacity. I plan to do a full discharge test in the future to rate the cells in mAh. I will be ordering more of these in the future.
EDIT: After cycling 12 of these packs a few times, I ran a discharge test on the cells, from 42V to 30V. The average capacity was 4150 mAh. These appear to be very good batteries and can discharge at least at 3 Amps. They had very little voltage sag as that rate, so they can likely go much higher. I would test higher, but the application I'm using them for doesn't draw that much current, and my tester can't dissipate heat fast enough to test any higher rates.