Hello david,
Thank you for your cooperation and understanding.
We have contacted you via Amazon, please check your message.
Have a nice day!
Best regards

Hello david,
Thank you for your reply.
This meter is powered by the measured battery.
If the power of battery become less, the display of the meter will become dark.
The power consumption of the meter is about 5-25MA.
As your description, the LED cannot work may be caused by the problem of the chip.
Could you please tell us your order ID so that we can find a solution for you?
Waiting for your reply.
Best regards

Hello Carl,
Thank you for writing in.
If you have any questions, please feel free to contact us.
Have a nice day!
Best regards

Hello Bruce,
Thank you for writing in.
Could you please tell us your order ID or the link of the product?
With your help, we can find a solution more quickly.
Best regards

Hello david,
Thank you for writing in.
This meter is used to monitor the voltage, cannot be used to monitor the battery level.
Could you please tell us more details of your operation, such as the input voltage,the wiring, the working environment?
If you can, we sincerely hope that you can send us some images to let us check the problem details.
You can send us the information by email (service at droking dot com).
Waiting for your reply.
Best regards

Hello Tom,
Thank you for your interest in our product.
Here are the recommendation for you:
For the voltage regulator:
Part number:#200151
DROK® Numerical Control Voltage Regulator Buck Boost Converter, DC 10-40V to 0-38V 6A Constant Voltage Current Step Up Step Down Transformer, Variable DC Power Supply with LED Display
Parameters:
Input voltage: DC 10-40V
Output voltage: DC 0-38V
Output current: 0-6A
Conversion efficiency: 92%
Working frequency: 150KHz
Short circuit protection: constant current
Operating temperature :﹣40℃~+85℃
Control method: numerical control + digital tube display
Voltage regulator/display resolution: 0.01V
Minimum resolution of power display: 0.001W
Current regulator/display resolution: 0.001A
Minimum resolution of capacity display: 0.001AH
Output ripple: ≤50mV
Weight: 116g
Dimensions: 100×80×21mm

Features:
1. Adopts advanced microprocessor, can regulate output voltage and current accurately;
2. Can step up and step down the voltage;
3. All display by digitals, convenient and easy to use;
4. Has constant voltage and constant current statue;
5. Uses 4 digits high brightness LED, can display output voltage, current, power and capacity and other parameters;
6. Voltage, current, power, capacity and other parameters can be switched to display automatically or manually;
7. Has output OUT, constant voltage CV and constant current CC indicators;
8. Can be set whether to output automatically when power on;
9. The set voltage and current values can be saved by key;
10. Has memory saving function, can store 10 groups of parameters and they can be freely stored and called out;
11. The maximum input current is 8A under step up mode, when the output voltage is much larger than input voltage, the output current may not be up to 6A.

For the relay:
Part number: #200088
DROK® Multifunctional DC 12V 1 Channel Relay Board Single-channel Relay Module 10A Portable Timer Switch Board Power Switch Circuit with 18 Mode and LED Digital Display Cyclic Time Delay
Parameters:
Input voltage: DC 12V
Control voltage: AC 0~250V / max.10A; DC 0~30V / max. 10A
Size: 2.59×1.57×0.67 inches

Module Functions:
The 18 functions include:
close or disconnect upon a certain set time;
limitless cycle timing mode 1 and 2 (cycle time 0.1 seconds to 270 hours adjustable);
self-lock relay mode;
trigger relay mode;
limited cycle timing mode 1 and 2(0.1seconds to 9999 seconds adjustable.).
Note: Functions 1-8 automatically start at power on;
functions 9-18 require high pulse signal (duration time no less than 20ms) trigger to start.

Timing pull
Timing disconnect
Timing pull then disconnect
Timing disconnect then pull
Limitless cycle timing mode 1 and 2
Limited cycle timing mode 1 and 2
Self-lock relay mode
Trigger relay mode
Trigger timing pull
Trigger timing disconnect
Trigger timing pull then disconnect
Trigger timing disconnect then pull
Limitless cycle timing mode 1 and 2
Limited cycle timing mode 1 and 2

Hope this can help you.
Best regards