Blue Digital Voltmeter

Good looking blue LED display with a very small footprint. Good accuracy from 0 to 30V running off of a 5V supply. These do not measure negative voltages.

They work accurately enough to give you a point of reference. Not expensive, so not top tier. Example: Vehicle is charging at 14.4v@idle as verified on multimeter at display connection, adjust pot to calibrate this display to match meter, then turn off car to see 12.4 on meter and 12.7 on this display.... As stated, ideally used as a point of reference (you are above or below your target range). The deviation will spread as the range gets wider, but it's perfect for a voltmeter in the dash or on an amp. Just a monitoring tool, not a diagnostic tool.

Put these on our battery bank to check voltage balance within the series. It came in a pack of five. There was .1 or .2 volt difference between them but I calibrated them to be perfect within .01v . Having 1 spare is good because it can be used as the calibrated one to check the others , except I blew it up accidentally by touching the back of it with a screwdriver and shorting it out, be carefull there sensitive. It would be good if the back was covered. You need to extend the wires because they are to short for a vehicle sized battery.

These meters are a great deal! Definitely worth the price. BUT - Read the description carefully. 1) Measurement capability is UNIPOLAR which means you can only measure POSITIVE voltages, NO NEGATIVE input or display is possible like with a digital multimeter or bipolar input panel meter. 2) The measurement Input (White wire) places a heavy burden (load) on the voltage source being measured. Input impedance averages about 100K Ohms. So, they cannot be used to measure high impedance circuitry without a buffer. The typical load placed on the source being measured is less than 1mA, which is okay when measuring low impedance circuitry like batteries, etc. - just a caution. 3) The wire insulation is too stiff and bulky and too short. If you are a skilled solderer (with a temperature-controlled soldering station) you could carefully replace the three wire cable. 4) You really need a blue plexiglass filter in front of the digits to increase contrast of the blue LED's and to make them more easily readable in bright light. 5) Factory calibration for all 5 meters was consistent but low. They all read 14.9VDC on a 15.007VDC calibrated source. That was easily corrected with the help of my Fluke 87V Digital Multimeter. They all now read correctly and linearly from 5VDC to 29VDC. SUMMARY: These are very accurate meters for the price as long as you understand their limitations. Longevity is still an open question at this point. However, at this price, they are a GREAT value, overall.

These are great little devices. I build various size battery packs and use these to determine their state of charge. The wide voltage range of 0-30v is perfect for my application They are very easy to use. If you don't need to measure < 3v than the simple two wire connection is all you need. It doesn't get much easier than that. Even in daylight the blue display is bright and easy to read. All 5 of the voltmeters I received measure accurately and identical. Good quality. Highly recommend.

These little voltmeters work just fine. The meter has three wires: red (positive) and black (negative) to power the meter, and a white wire you connect to the point where the voltage is being measured. There is a tiny Phillips screw on the back of the meter to calibrate the reading. I found that the little voltmeter agreed with my multimeter down to a hundreth of a volt. I did not need to calibrate the meter. These are inexpensive and work well. I like them.

I love these displays, they work pretty decently for the money. I do a lot of research with cells, and I like to have an idea of its voltage all the time. Note: if you really need to measure low voltages, lets say, below 3 volts, you will need an external power supply or battery to feed each display. Which makes sense because if you are testing a dead (zero volt) battery with these displays, you won't see any data. for voltages over 3 volt they work as intended. One thing to notice is I had to calibrate one of the packs. I compared the readings with my digital multimeter and it was a little bit lower than the real thing. The rest of them were perfectly fine. In my experience, I can recommend these displays, and most likely I will be buying more in the future.

The screw holes are so small and with limited space as well as a weak mounting plate making mounting these very difficult. Additionally, the wires are such a small gauge (~22g) that it makes it challenging to connect to a fuse panel or other terminal. Additionally, the meter itself seems weak and vulnerable to being damaged unless in a protected enclosure.