GrainMate GM-101 User Manual

Congratulations on purchasing a GrainMate GM-101 Grain Moisture Meter. Before using this product please read the instruction manual thoroughly and carefully to learn how to operate and service your device correctly.

Table of Content

1.0 Introduction

2.0 Setup

3.0 Operation

4.0 Troubleshooting

5.0 Servicing

6.0 Warranty


1.0 Introduction

Thank you for purchasing the GrainMate GM-101 Grain Moisture Meter. GrainMate makes it easy to accurately determine/monitor the moisture content in grains before/during storage. It is an effective, low cost solution for the reduction of post-harvest losses in grains due to storage at improper moisture levels.

GrainMate is ideal for measuring the moisture content of several commodities including corn, paddy rice, chickpea/cowpea, wheat, sorghum and soya bean with the capacity to support up to 32 different crops.

It’s simple and straight-forward design makes it easy for anyone to use with little or no guidance and its sensitive sensor lying within a strong, robust aluminium probe enables easy insertion into bags and bulk samples of grains, feed and agricultural commodities.

GrainMate is manufactured in Ghana by Sesi Technologies with support from Feed The Future, The Post-harvest Loss Reduction Innovation Lab, the US Department of Agriculture and the Department of Agricultural and Biosystems Engineering, KNUST, Kumasi.


1.1 Features

  • 16 x 2 liquid crystal display which gives a large digital readout of moisture, temperature, and relative humidity.
  • Accurate readings of relative humidity (+/ 2%) and temperature (+/ 0.2°C) over given range.
  • Reaches equilibrium within 2 to 5 minutes.
  • Lightweight handheld unit which is easy to carry around.
  • Easy to use. Simply insert, select your crop and read. No sampling, weighing or grinding needed.
  • Strong aluminium probe for easy insertion into bags and bulk samples of grains, feed and commodities.
  • Battery operated. Uses a single 9v battery to power device for a long time and firm handle constructed to perform even in harsh conditions.
  • Calibrated for measurement of moisture in multiple grains with the capacity to support up to 32 different grains and legumes.

2.0 Setup

2.1 Contents

Each package of the GrainMate Grain Moisture Tester includes

  • GrainMate Handheld Unit
  • GrainMate Metal Probe
  • 9V Alkaline Battery
  • Carry-on Leather Bag
  • Instruction Manual
  • Warranty card


2.2 Parts and functionality

    1. Liquid Crystal Display – Displays relevant information as shown
    2. Temperature – Indicates the current temperature around the grain in degree Celsius
    3. Relative humidity – Indicates the current relative humidity around the grain in percentage
    4. Moisture  – Indicates the current moisture reading (MCwb means Moisture Content Wet Basis) in percentage
    5. Selected Commodity – This indicates the crop or commodity which has currently been selected.
    6. Stability IndicatorWhen the * symbol is displayed, it indicates that the moisture reading is now stable.
    7. Power On Button (Red)Turns the device on
    8. Switch Grain Button (Yellow)Cycles through available commodities which can be tested and selects one
    9. Power Off Button (Black)Turns the device off
    10. Female Connectorreceives the male end of the probe jack
    11. HandleLets you insert the probe into a bag or bulk of grain
    12. Male connector – Connects the sensor to the probe
    13. Metal Probe
    14. Sensor

2.3 Inserting the battery

The moisture meter is supplied with a standard 9V alkaline battery. The steps below show how to insert the battery into the device.

  • Carefully remove the handheld unit from the elastic straps.
  • Slide the back cover to open the battery compartment of the handheld unit to reveal 9v battery holder.
  • Snap the 9V battery into the battery holder, insert back into the battery compartment and slide the battery compartment cover up. Make sure the polarity of the battery is correct and are completely seated.

2.4 Powering the Moisture Meter

  • Before you power the moisture meter, ensure that the probe is connected to the handheld device by inserting the male connector of the probe’s cable into the female port of the handheld device.
  • A “Click” sounds shows that the cable has been inserted into the female port correctly and firmly.
  • Now press and hold the power button (red button on the left) for 2 seconds until the LCD turns on and “SESI TECHNOLOGIES” appears on the screen.


3.0 Operation

3.1 Operating Principle

GrainMate Grain Moisture Meter calculates the equilibrium moisture content (EMC) in a bulk of grain using the temperature and relative humidity around the sample. These readings are plugged into EMC curves/models which have been generated for local varieties of the commodities that GrainMate currently supports to calculate the moisture content of those commodities.

3.2 Operating Conditions

Measurement of samples can be taken when the grains have been bagged or while they are still being dried.

Prior to measuring the moisture content of the grains in bags, ensure that the grain has been stored in the bag for at least two hours.  

To use the meter while the grains are still being dried, ensure the grain is heaped to a height of at least 50 cm and insert the probe near the bottom of the heap, ensuring that the tip (sensor end) of the probe is fully covered by the grains.

The meter is most accurate when the grain and tester are between 60°F (16°C) and 90°F (32°C). The unit will, however, operate at temperatures between 32°F (0°C) and 113°F (45°C). For best results, grain temperatures should not be below 40°F (4°C) or above 110°F (43°C).

3.3 Commodity Types and Representations

GrainMate currently supports seven commodities which are represented by following.

  • Maize or Corn is shown as CornY
  • Soyabeans or Soybeans is shown as Soybn
  • Paddy Rice is shown as RiceR
  • Sorghum is shown as Srghm
  • Hard wheat is shown as Wht,H
  • Soft wheat is shown as Wht,S
  • Chickpea is shown as ChPea

3.4 Taking A Reading

  • For a bagged grain, make a small opening on the seal of the bag and insert the probe. Ensure the probe tip and sensor are as close to the middle of the bag as possible.
  • Long press the red button for 2 seconds to turn the device on. The meter will briefly display the company and product name while the device boots.
  • If the grain type displayed at the bottom right corner of the screen is not the appropriate grain type you want to measure, you’ll need to select the appropriate grain by cycling through the available grains.
  • To select the appropriate grain type, press and hold the yellow button to cycle through available grains and release the yellow button when the required grain is displayed.
  • Wait for about 5 minutes for readings to stabilize before reading the moisture content
  • A * (star) symbol displayed at the bottom right corner of the screen signifies that moisture reading is stable and can now be recorded.

Grain that has been dried on tarps or mounded and covered overnight can also be measured before spreading the next day.  The same procedure above is used to measure moisture content in grains.

After reading the moisture content, press the black button to turn off the meter. Remove the probe from the grain and detach it from the meter. Remove the battery from the meter and store the meter, probe and battery in its leather bag until the next reading.

To enhance accuracy, you may take multiple reading for each sample.

3.5 Interpreting the Moisture Content (MCWB) Reading

Each grain type has a recommended moisture range depending on use. The following table shows the recommended moisture levels for each of the commodities currently supported by GrainMate.

Grain Type Better(%) Good(%) Bad(%)
CORN (CornY) 10-13

Your grain is dry enough for both and long term storage of more than 6 months.


Your grain is dry enough for short term storage. Consider drying it a bit more for long term storage of more than 6 months.


Your grain moisture content is too high. Storing at this moisture level could lead to the growth of mould and aflatoxins.  Please dry some more before storage..

SORGHUM 10-13 13-16 >16
WHEAT 10-13 13-13.5 >13


11-13 >13
RICE 9-12 12-14 >14
CHICKPEA 10-13 13-14 >14

For long term storage periods of more than six months, you should ensure that the moisture content is in the range of “Better”. For short-term storage of less than six months, ensure that the moisture content is not above the maximum of the “Good” range.


4.0 Troubleshooting

4.1 Possible Issues, Causes and Solutions

The following are possible issues you may encounter while using the moisture meter and solutions to these issues.

Issue Causes and Solution
Meter does not power up or loses power occasionally.

The display is dim or flickers or the backlight does not operate.

Likely Causes

The battery is weak and needs to be replaced.


Ensure that the meter is fully on by pressing and holding the power button.

If the step above does not work, remove the battery from behind the meter and replace with a new 9v battery. Good quality alkaline batteries are recommended.

It is also advised to remove the battery from the meter after usage.

Meter displays “Check Sensor Connection!” Likely Causes

The probe has not connected to the main body of the meter at all or has not been connected properly.

There is a break in the sensor cable or some loose contact between the sensor telephone jack and the receiving port on the body of the meter.


Insert the sensor telephone jack into the receiving port on the body of the meter. If it is already inserted, remove and reinsert the jack and listen for a “click” sound.

If reinserting does not fix the issue, it could mean the probe has to be serviced or replaced. Contact our support team at [email protected] to report the issue for assistance.


5.0 Servicing

5.1 General Care and Maintenance

  • To save battery power, always insert the probe into a bag of grain before switching on the meter.
  • Keep the meter in a cool and dry place after use, most preferably in its leather bag
  • Protect the probe from moisture and dust by wrapping the tip in a plastic bag or cloth after use.
  • Do not drop the meter and the probe.
  • Take care when removing the 9V battery from the battery clip as pulling too hard could damage the battery clip terminals or tear the battery cable.
  • To save battery power, remove the battery from the meter when it is not in use.

5.2 Replacing the Battery

The meter is supplied with a 9-volt alkaline battery which powers the device. After some time, you may need to replace the battery. One sign that could mean you need to replace the battery is when the backlight goes dim.

To replace the battery,

  • Slide the back cover to open the battery compartment of the handheld unit to reveal 9v battery holder.
  • Using a pointed object such as a screwdriver or a small knife, lift the bottom end of the battery from the compartment.
  • Gently pull off the old battery from the battery clip, taking care to not damage the clip in the process.
  • Snap the new battery unto the battery holder, insert back into the battery compartment and slide the battery compartment cover up.

It is recommended to use high-quality alkaline 9-volt batteries to ensure that they last longer.

6.0 Warranty

This product is warranted in Ghana by Sesi Technologies Ltd. for free replacement or repair for a period of six months commencing on the delivery date. During the warranty period, Sesi Technologies will repair or replace the product provided they are sent to the address below, with proof of original purchase.

If a warranty service is required, service will be contingent upon inspection to ensure abuse or neglect in maintenance or exposure to harsh environmental conditions has not occurred. The inspection and analysis will be performed by the supplier/manufacturer. 

It is the responsibility of the purchaser to cover all shipping charges of defective units to the manufacturer/supplier as needed in order to perform warranty service. 

7.0 Contact

Sales / Customer Support

Email: [email protected]
Telephone: +233501359999


Sesi Technologies Ltd
Plot 18, Block 7,
Ayeduase New Site,
Kumasi, Ghana