Review, Teardown Keweisi KWS V2. USB Tester. Its almost been one year since Ive looked at USB charger doctor style devices, but having reverseengineered, tested and modified one, I didnt think Id ever bother with them again. That was, until I saw the Keweisi KWS V2. Swamy Handbook 2011 Pdf there. USB Tester in one of bigclivedotcoms videos about a power bank. As someone had mentioned in a comment on the prior articles, the products have evolved over time and integrating m. Ah display units are now available. Buy Beyerdynamic DT 770 PRO, 250 ohms OnEar Headphones Amazon. FREE DELIVERY possible on eligible purchases. View and Download Fiio Andes user manual online. USB DAC headphone amplifier. Andes Amplifier pdf manual download. If this setting is ON, Magic Lantern will write out a metadata file for the each movie to MVI1234. LOG numbered after the movie. The log file contains lens and. I suppose it would only be right for me to go and grab one for myself and test it. A quick trip to e. Bay, AU1. 0 and a month later, I had a new toy to test. Unboxing. Rather uninspiringly, the unit came in a zip lock anti static ESD shielding bag and that was it. On the front, the label claims the unit to meter voltage from 4 2. V 1, meter current from 0 3. A 1, count time up to 9. Ah. Aside from this, there was nothing no manual, no leaflet. I suppose thats fine its a pretty straightforward device. Once extracted from the packaging, it was a little disappointing to see that it was just plopped inside without any love, so the plastic outer has some fine scratches. Of course, the scratches are purely cosmetic and dont affect the functioning of the device at all. Keweisi is not a brand Ive heard of, but it seems the meters are somewhat popular. Fiio E5 Headphone Amplifier Manual' title='Fiio E5 Headphone Amplifier Manual' />It has an USB A M connector on one side, and an A F connector on the other, with no wires to add resistance. The translucent case allows you to see inside so a teardown isnt really needed and see the LCD display which is an inverted type. ULIFE026300_01_L.jpg' alt='Fiio E5 Headphone Amplifier Manual' title='Fiio E5 Headphone Amplifier Manual' />USA. View and Download FiiO E5 user manual online. Portable Headphone amplifier. E5 Amplifier pdf manual download. Google is compensated by these merchants. Payment is one of several factors used to rank these results. Tax and shipping costs are estimates. Aside from that, there is a reset button that is used to clear the integrated timem. Ah values. This is accessed from the top and needs to be held for a few seconds to clear the values. The rear shows a 0. The casing is simply clipped together. The USB connector was a bit crooked on this sample, and bending it is not advisable as the LCD is mounted to the board and shows strain when pressure is applied. Teardown. Theres really nothing to it. A careful poke at the case with a good fingernail and it comes apart. Inside, the backlit LCD glass is directly soldered onto the PCB. The amount of solder used on the joints are highly variable, and seem to be a little on the low side since they havent nicely flowed through the vias and all over all the pads especially for the USB connectors. Its not entirely necessary to do that, and its probably still fine as it is. I suppose in the case of the LCD, theres a good reason why the soldering is done so casually, as applying excessive heat is likely to damage the glass seal that keeps the crystal in and would destroy the LCD altogether. This type of pin arrangement as opposed to elastomeric connector leaves the LCD vulnerable to stress being conducted through the board, so bending the USB connections can potentially strain or break the display. The underside shows exactly what I mentioned earlier U1 appears to be a microcontroller with its markings rubbed off. Fiio E5 Headphone Amplifier Manual' title='Fiio E5 Headphone Amplifier Manual' />U3 is a gob top chip mounted directly on the board, and is probably the LCD display controller. U2 is probably a voltage regulator, but it was not confirmed. S1 is a 2. 4C0. 2S 2. EEPROM, which is probably used to store the integrated data values. One thing I did notice is that D1, which is supposed to be a diode, was replaced with a 0 ohm resistor. I didnt carefully check if this was in series with the actual USB output, but if it was, it may have been replaced to avoid voltage drop contribution from the diode. However, this alteration may mean that the unit is not going to survive being plugged into a USB port with reversed polarity. In Use and Testing. Its extremely simple to use. Plug it in, and basically off it goes. When the current reading is 0. A or higher, the integration will run to accumulate charge time blinking colon indicates it is running and charge in m. Ah. Once the current falls below the threshold, the time and integration stops. The last value is stored in the unit itself, and is shown when power is re applied unless reset. Resetting the unit involves pressing and holding the reset button for about five seconds. On the whole, I found it quite a nice unit. Although the LCD characters are a little small, the backlight is extremely efficient and the display reads quite well. The viewing angle is somewhat limited though. The display features two decimal places for voltage under 1. V and current. Above 1. V, only one decimal place for voltage is shown. The display updates about twice a second, and is sometimes jumpy especially for rapidly changing spiky loads. The wide voltage range of 4 2. V allows for compatibility with the latest Qualcomm Quick Charge capable power adapters which can output up to 2. V in some rare cases, making diagnosis of quick charge issues more efficient. Integrated Charge. I decided to see how good its charge integration was by testing it with my Nitecore MH1. I drained it and went through a full charge with it. Testing with the Keysight U1. A and the modified USB Charger Doctor shunt produced a result of 2. Ah and 5h 5. 5m 2. As we can see from this result, the Keweisi has an integrated current of 1. Ah less, although the charge time is less as well. This may be because the dischargecharge termination may have been slightly different between runs. However, it still does seem to indicate that the units charge integration ability is quite good as an indicator. I also tested it with an Anker Powercore 1. Qualcomm Quick Charge 2. The power bank was run down to flat, and then recharged with the meter integrating the charge. Its important to remember that m. Ah is not a measure of energy. It is a measure of current flow integrated across time, and to derive energy requires the voltage as well. As a result, we can see 5. Ah was fed into the power bank over 4 h 4. V. This is a total of 4. Wh which at 3. 7v is equivalent to 1. Ah. Note that the value is higher than the 1. Ah of the power bank due to conversion losses and losses in displaycontroletc. Assuming the cells are 1. Ah, the charging efficiency was 8. Note that different types of charging circuitry exist. Switching converter chargers such as that in the Anker power bank will convert the energy with 8. Linear chargers merely drop and lose the excess voltage e. MH1. 0, so the displayed figure corresponds to the m. Ah of charge going into the battery except for losses in indicator lights etc and are lower energy efficiency 7. Unfortunately, its not always easy to know what is in use unless youve peeked inside or the figures are obvious. One of the biggest failures is that the unit only integrates charge and not energy. It appears that they have everything they would need to do it for energy and record m. Wh by multiplying voltage and current pairs, as this would be helpful as the supply voltage may change during the charge e. Qualcomm Quick Charge 3. V granularity and step up and down on demand. This would make the delivered energy unambiguous and potentially make it very handy for things like metering solar energy charge into a battery for a small scale system. It would be nicer if the unit had some way of storing multiple results for recall and more extensive data logging features but I suppose that might be asking for too much.