150A RC Watt Meter High Precision Power Analyzer Digital LCD Screen Amp Meter for Voltage(V) Current(A) Power(W) Charge(Ah) and Energy(Wh) Measurement

I purchased two of these battery analyzers/meters, One of them was accurate to within 1% of all functions. The other was off by 4% and therefore not acceptable for my purposes and the claimed accuracy. Amazon has a ton of these similar type of meters which are distinguished by a blue back lit display. These units had a black numeral on a white background and are very easy to read. All of the other models of the blue back lit display seem to be made by the same company and design, and all are inaccurate by a very large margin. I purchased at least two of those from different amazon sellers in the past and both have the same inaccuracy. And in reading the reviews of the blue background meters many said that they were inaccurate. The amps and volts of these other blue units is off by about 3 percent on voltage and amperage which is not terrible but the AH or accumulated ampere hour values are off by severe differences - so that a 100 amp hour battery will show up as 54 amp hours. These blue units all look the same in their display window and bodies of their housings. They are very cheap usually around 15 dollars. All seem worthless if you want to know the capacity of your battery to determine change and discharge or when the battery is failing - Avoid those. I liked these white backround, black number units for they are at least failry accurate and if you get a good copy, it is quire accurate. In addition you can take the variaous functions and keep the unit on displaying just one in real time that you are interested in without having to transistion and toggle repeatedly between 6 functions. In the blue backlit model those parameters continuously change once a second and is hard to read and annoying. In addition with these white background units you can turnoff the diplay light and reset it as well with the button on the face ahter than having to disconnect the blue units for a reset. So overall these white background units are a very good value for the money and decent but not incredible accuracy. Beware of cheap units claiming extreme accuracy except for these.

The included data sheet (11/2022) mentions connecting an auxiliary battery to the 3-pin connector when the battery source being monitored is less than 4.8 volts. This is because the device itself normally uses the battery being monitored as its own power source. But the device needs at least 4.8 volts to operate. However, the diagrams only show a 2 wire connection without indicating which of the 2 pins on the 3 pin connector to use. It also shows to connect positive auxiliary battery to the top most pin. However, the video in the product descriptions clearly shows the black (negative) wire connecting to the upper most pin and the red (positive) auxiliary battery wire connecting below it which is the middle pin of the 3. I tested applying an auxiliary battery with positive to the middle pin and negative to the top most pin and it worked.The similar device ASIN B0B8VWNY9X has photos with labeled PIN numbers and functions that agree with the above.The resistor that senses the current is inline with the negative return ground lead not inline with the outgoing positive lead. The positive input lead is hardwired directly to the output lead on the circuit board. Not a problem unless your load gets its ground connection somewhere other than directly back to this device’s ground lead. For example, in an auto application if the load is grounded to the vehicle chassis.Circuit board is well made and clean.

Very easy to read, well constructed, backlit on/off control, reset totals without disconnecting, selectable totals instead of the numbers cycling automatically making it easy to read. However the voltage being low by 2.2% may sound fairly accurate but when I measure 12.96 volts on a battery which is really 13.24 it means a big SOC difference for a LiFePo4 battery bank. It should be fairly easy to have a calibration trim pot to adjust like in some $3 meters I have making it very accurate but they don't. With the amps low at the same time the resulting watt hours will be even further in error.

This is a robust and capable widget, but they really need to double the length of the attached wires.

this product is just More China Garbage .....hooked it up and it failed right awayAmazon sells more Chinese products that are a waste of time and just garbage that fails or is not what it says it is before you spend your money on it.. why do the allow China to sell on their platform ..waste my time my gas to drop it off at a return store ..this happens frequently ill be looking else ware for my needs Amazon has become a arm of chinas economy profit and selling subpar items from them