How to Use a Voltmeter: Steps and Practical Picks
As an Amazon Associate we earn from qualifying purchases. Details
A voltmeter measures the difference in voltage between two points in a circuit, so you connect it in parallel with the part you are testing. Set the meter to AC or DC and choose a range above the expected voltage. For DC, the red lead goes to the positive side and the black lead to the common side.
Most mistakes come from the wrong function or range, or from probes left in the wrong jacks. Check the meter CAT rating and voltage rating before connecting it to mains wiring, and inspect the leads for cracks. If a reading looks unlikely, stop and recheck the setup.
Quick answer
Five of the six products are digital multimeters. The AstroAI is titled 2000 counts and is the only one with a written DC voltage ladder, up to 600V. The FS899L and the model 620 meter are titled 6000 counts, and the TM-510 is titled 4000 counts. The WINAMOO is a test light, not a multimeter.
Decide which voltage range and format you need, then compare the listings that state it.
Comparison table
| Product | Counts or range | Power source | Size or weight | Notes |
|---|---|---|---|---|
| AstroAI | 2000 counts; DC up to 600V | Battery | 0.15 kg | Fuse protection 250 V, 10 A |
| Multi tester (orange and black) | Not stated | Battery | Not stated | Continuity, ohm, volt, amp |
| FS899L rechargeable | 6000 counts | Not stated | 5.98 x 2.87 x 0.79 in | USB rechargeable, color screen |
| TM-510 | 4000 counts | Battery | Not stated | Auto-ranging |
| WINAMOO test light | 3-48V (title) | Corded | Not stated | Test light, not a multimeter |
| Model 620 meter | 6000 counts | Corded Electric (as listed) | Not stated | Auto ranging |
The products in detail
AstroAI Digital Multimeter Tester, 2000 Counts, DC AC Voltmeter
A 2000 count digital multimeter whose title names a DC AC voltmeter plus ohm, volt and amp readings. The listing fields give battery power, a compact style and a blue body. Measured details add a weight of 0.15 kg, fuse protection of 250 V and 10 A, and DC voltage entries of 200mV, 2V, 20V, 200V and 600V.
Who it suits: A buyer who wants the range ladder written out, so the DC voltage steps can be checked against the voltage expected.
Pros
- DC voltage steps from 200mV up to 600V are listed
- Fuse protection of 250 V and 10 A is listed
- Weight stated as 0.15 kg
Cons
- Only 2000 counts, the lowest count in this group
- The environmental conditions entry also shows 600 V and 300 V figures that the listing does not explain
Skip if: You want more counts, or auto-ranging stated in the title.
View the AstroAI 2000 count multimeter on Amazon (affiliate link)
Digital Multimeter Voltmeter Battery Voltage Multi Tester
A multi tester whose title covers continuity, ohm, volt, amp and DC AC current. The listing fields give battery power, a modern style and an orange and black color entry.
Who it suits: A buyer who wants continuity and ohm readings together with voltage in one unit.
Pros
- Title names continuity, ohm, volt, amp and DC AC current
- Battery powered
Cons
- No weight, size or voltage range is stated
- No count figure is given
Skip if: You need a stated voltage range or size before opening the product page.
View the orange and black multi tester on Amazon (affiliate link)
USB Rechargeable Digital Multimeter, 6000 Counts, Color Screen, FS899L
A 6000 count digital multimeter with a large color screen and backlight, listed under the FS899L name and described as USB rechargeable. The fields give a digital style, a color entry of One Color and dimensions of 5.98 x 2.87 x 0.79 inches.
Who it suits: A buyer who wants a rechargeable meter with a large screen and full dimensions to check against a tool pouch or drawer.
Pros
- 6000 counts
- USB rechargeable and backlit color screen named in the title
- Full dimensions stated: 5.98 x 2.87 x 0.79 inches
Cons
- No power source field, so battery and charging details need a check on the product page
- No weight stated
Skip if: You want a plain battery meter, or you need the charging details spelled out in the fields.
View the FS899L rechargeable multimeter on Amazon (affiliate link)
TM-510 Digital Multimeter, 4000 Counts, Auto-Ranging Voltmeter
A 4000 count smart digital multimeter whose title names auto-ranging and a voltage tester role. The fields give battery power, a TM-510 Smart Digital Multimeter style and a green body.
Who it suits: A buyer who wants auto-ranging and a count between the 2000 and 6000 count listings.
Pros
- 4000 counts with auto-ranging in the title
- Battery powered
Cons
- No weight, size or CAT rating is stated
Skip if: You need a CAT rating confirmed in the listing.
View the TM-510 multimeter on Amazon (affiliate link)
WINAMOO Automotive Test Light, 3-48V LED Digital Voltage Display
This is a test light, not a multimeter. The title names an automotive circuit tester with a 3-48V LED digital voltage display. The fields give corded power, a compact style and a black body. It is included here because it shows voltage, but it covers only the range in its title.
Who it suits: A buyer whose voltage checks are on vehicle circuits between 3V and 48V.
Pros
- Shows a voltage readout within 3-48V
- Compact style
Cons
- Not a multimeter, so no resistance or continuity readings are stated
- No CAT rating is stated, so it is not for mains work
Skip if: You need to measure household voltage or want a general-purpose meter.
View the WINAMOO test light on Amazon (affiliate link)
Smart Digital Multimeter Tester, 6000 Counts, Auto Ranging, Model 620
A 6000 count smart digital multimeter with an auto ranging digital voltmeter. The fields give a power source of Corded Electric, a style entry of 620 and a black body.
Who it suits: A buyer who wants 6000 counts and auto-ranging and will compare it with the FS899L on size, display and included leads.
Pros
- 6000 counts with auto-ranging in the title
- Smart meter wording in the title
Cons
- The power source reads Corded Electric for a multimeter, so check the product page to see how it is powered
- No weight, size or CAT rating is stated
Skip if: You need the power details and size confirmed from the listing.
View the 6000 count 620 multimeter on Amazon (affiliate link)
Buying checklist
- Match the AC or DC function and the voltage range to the circuit you will test.
- Check the CAT rating before touching mains wiring; most listings here do not state one.
- Decide whether you need extras such as continuity, ohm or amp readings.
- Compare counts only against other counts, and size only against size.
- Confirm the power source, including charging for the rechargeable model.
- Inspect the leads before every use.
Related guides
These guides cover testing outlets with a voltmeter or meter:
- How to test an outlet with a voltmeter
- How to use a voltage meter to test an outlet
- How to test a wall outlet
FAQ
How do I connect a voltmeter?
Connect it in parallel with the part you are testing. For DC, the red lead goes to the positive side and the black lead to the common side. Choose AC or DC first and pick a range above the expected voltage.
Which listing states a DC voltage range?
The AstroAI lists DC voltage entries of 200mV, 2V, 20V, 200V and 600V. The other listings do not spell out a range in the fields shown.
Is the WINAMOO a multimeter?
No. It is an automotive test light with a 3-48V LED digital voltage display. It does not state resistance or continuity readings.
Do the counts matter?
Counts describe display resolution. The AstroAI is titled 2000 counts, the TM-510 4000 counts, and the FS899L and model 620 meter 6000 counts. Compare them only with each other.
What should I check before using a meter on mains wiring?
Check the CAT rating and voltage rating, and inspect the leads for cracks. Most listings here do not state a CAT rating, so confirm it on the product page or leave mains work to a licensed electrician.
Closing note
For basic voltage checks, a multimeter whose range and rating you can confirm is a better buy than one with more features and fewer stated limits. Use the table to shortlist, then confirm the details on the product page.
