DSN-VC288 voltmeter and current meter review (in short they are shite)

I bought one of the commonly available dual display panel meters with the part number DSN-VC288 which has three digits and shows voltage to 1 decimal place and current to 2 decimal places. It can measure 0-99.9V and 0-10A and features a red display for the voltage and blue for the current. There seems to be several versions of these panel meters; some with 4 digits and some with three. Some of the three digit ones appear to have auto ranging showing voltage to 2 decimal places if less than 10V however mine does not have this facility.

They look smart enough but as everything that is cheap & made in China, they don’t work as intended, are unreliable, poor quality and cannot be used for anything were accuracy is required. There are two ways of connecting these depending on if the supply voltage is different to the voltage being measured or if the meter gets it’s power from the same source it is measuring. In my case I used a seperate supply as the meter stops working below 4V. I definitely did connect it up correctly and have done a bit of research into these.

The problems I had was simply the accuracy is way off. It is advertised as 0.1% accuracy for voltage and 1% for current however this definitely isn’t the case. Out of the box, a 5.0V reference voltage measured on a calibrated DVM showed 5.3V and a 20V reference showed 21.8V. On the rear there is a little trimpot so I managed to adjust this to get a reasonable result and now 5V reads 5.0V but 20V reads 20.5V so if this thing can measure up to 100V then the scale appears to be non linear and it is impossible to get an accurate reading throughout the range. I fiddled with it for ages and the accuracy is just unacceptable. In the end I used it to measure voltages up to 20V with emphasis on accuracy being at the bottom end of the scale.

Now as for the current this is a different story. I found that this was showing 0.67A with a 0.5A load and 2.3A with a 2.0A load and the adjustment trimmer was already at the minimum value. The meter does read zero when no current is flowing so the reset trick I found on the web did not work. I also found that some of the component values on the board differ to photos and a schematic I found implying incorrect value components have been fitted.

So I bought another and guess what, that was exactly the same although the current reading was slightly better. I guess with a bit of reverse engineering I could try changing component values but the tiny SMD resistors will be troublesome to replace with my limited equipment at home.

So don’t by these useless pieces of crap unless you don’t care about accuracy. If anyone has any suggestions on how to improve their accuracy especially the current reading high despite adjustment please let me know. I’m sure swapping out a resistor with a different value would fix this but it’s more trouble than it’s worth and I risk rendering the module unable to be used at all.

I’ve checked some Amazon reviews (these are sold under several brands such as KeeYees, Geekcredit, Hi-Life, Drok etc) and it seems others have the same problem with the current reading high. Some don’t so it seems pot luck if you get one that works or not but it would be interesting to know what the component values are on one that works. Particularly the value of the current adjustment trimpot and the adjacent resistors.