how quickly will it inflate a queen sized air mattress?

Its an inverter, not a compressor, so it will inflate your air mattress at the same rate that an overripe banana would... ie, it wont. It cant. So eat the banana and purchase an inflator. Now, if you are using this inverter it to *power* an inflator, then the inflator will work at the same speed as it would plugged into a wall socket. But I’d still eat a banana because its clear you have a potassium deficiency (but I’m not a doctor so you may want a second opinion).

is this a three phase inverter?

500W Three Phase @ $60? In what world is that?

I'll be attaching a relay on the (+) connector, so I'll keep the switch in the ON position all the time, is there a problem with this setup?

Max power draw is very close to 40 amps (34-38 depending on battery voltage). The relay would have to be a 50 amp rating MINUMUM, and higher if you can get it. I believe the next common rating is 70 or 75 amps.

What size are the posts on the inverter? 5/16 or 3/8?

It is neither. The posts on my unit are 3/16, which is adequate for the loop connectors and any load I'll be creating while using the unit.

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BESTEK 500W Pure Sine Wave Power Inverter DC 12V to AC(2 Outlets) 110V Car Charger Plug Inverter Adapter Converter with 4.2A Dual USB Charging Ports, ETL Listed

BESTEK 500W Pure Sine Wave Power Inverter DC 12V to AC(2 Outlets) 110V Car Charger Plug Inverter Adapter Converter with 4.2A Dual USB Charging Ports, ETL Listed

Product ID: 177529791

Details

Battery Capacity
12
Brand
BESTEK
Power Source
DC
Recommended Uses For Product
Vehicle
Wattage
500 watts

⚡500W Pure Sine Wave Output

🔌2 AC Outlets + 2 USB Ports (4.2A max)

🛡️Multi-layer Safety Protections

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3969959₫

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Details

Battery Capacity
12
Brand
BESTEK
Power Source
DC

Description

🔋 Power your on-the-go lifestyle with flawless, pure sine wave energy!

DUAL AC USB CHARGING PORTS - Power laptops, tools, and smartphones simultaneously with 2 AC outlets plus smart 4.2A USB charging.
FLEXIBLE POWER INPUT OPTIONS - Plug into your 12V cigarette lighter or connect directly to your car battery with included clamps for max power.
COMPACT TRAVEL READY DESIGN - Lightweight 2.2 lbs unit fits perfectly in your car or DIY power station—ideal for camping, remote work, or emergencies.
SEAMLESS PURE SINE WAVE POWER - Delivers clean, grid-quality AC power for sensitive electronics—no buzzing, no glitches.
ROBUST THERMAL FUSE PROTECTION - Built-in fan, aluminum casing, and replaceable fuses keep your devices safe and inverter cool.

The BESTEK 500W Pure Sine Wave Power Inverter converts your vehicle’s 12V DC into clean 110V AC power with two AC outlets and dual USB ports delivering up to 4.2A. ETL listed and equipped with advanced safety features including thermal sensors, replaceable fuses, and overload protection, it ensures reliable, quiet operation for sensitive electronics. Compact and versatile, it supports both cigarette lighter and direct battery connections, making it perfect for camping, DIY power setups, and emergency backup.

Specifications

ASIN	B082MDRC64
Antenna Location	Vehicle
Battery Capacity	12
Best Sellers Rank	#9,408 in Automotive ( See Top 100 in Automotive ) #21 in Power Inverters
Brand	BESTEK
Built-In Media	500W Pure Sine Wave Power Inverter DC 12V to AC 110V Car Plug Inverter Adapter Power Converter with 4.2A Dual USB Charging Ports and 2 AC Outlets Car Charger
Color	1 Red
Customer Reviews	4.5 out of 5 stars 3,294 Reviews
Electrical Output Waveform	Pure Sine Wave
Energy Specifications Met	ETL
Frequency	60 Hz
Input Voltage	12 Volts
Item Dimensions L x W x H	8.7"L x 4.3"W x 2.4"H
Item Weight	2.2 Pounds
Manufacturer	BESTEK
Mfr Part Number	MRZ5011BU
Model Name	MRZ5011BU
Model Number	MRZ5011BU
Number of Outlets	4
Output Power	500 Watts
Output Voltage	110 Volts
Power Source	DC
Recommended Uses For Product	Vehicle
Standby Power Shutoff	90
Unit Count	1.0 Count
Voltage	110 Volts
Warranty Description	2-year Warranty
Wattage	500 watts

Reviews

J**N

1.08.2022

D**S

23.06.2023

S**G

10.11.2025

G**Y

8.04.2026

C**S

12.12.2024

O**O

20.07.2025

B**N

22.07.2025

P**X

10.08.2025

M**O

30.04.2026

L**.

7.04.2023

A**R

30.04.2026

R**Z

10.02.2022

A**R

14.01.2024

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Desertcart purchases this item on your behalf and handles shipping, customs, and support to Vietnam.

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