Battery Jump Starter 4120A Peak Portable Car Starter - Powerful 12V

In this review the YESPER YJS40 is assessed as a heavy-duty portable jump starter aimed at drivers who need dependable emergency starts and portable power. The single biggest reason to buy is its real 4120A peak starting capability combined with a true 24000mAh capacity, which makes it suitable for nearly any 12V vehicle and gasoline engines up to large diesel sizes; the unit also doubles as a multiport power bank and LED emergency light. For owners who want a compact, rugged jump box that can force-start a dead battery and run DC accessories, this is a practical choice.

Key Features

• 4120A Peak Current: Delivers a high starting surge that can jump start many 12V vehicles and gasoline engines as well as diesel engines up to 10.0L.
• DSLI IV Intelligent Control: Microcomputer-managed output raises voltage to as much as 14.8V and optimizes starting current for faster, safer cranking.
• Real 24000mAh Capacity: The stated 24000mAh (88.88Wh) battery gives many repeat jump starts on a single charge and avoids inflated capacity claims.
• Versatile Output Ports: Built-in USB, QC USB, and Type-C ports plus a DC 15V/10A output let the starter power inflators, fridges, and run USB devices.
• LED Work Light: Three light modes (flash, strobe, SOS) provide useful illumination for roadside emergencies and outdoor use.
• Rugged Construction: Fire-proof ABS housing and resistance to rain, dust and drops make it suitable for garage and outdoor use.

Who It's For

The YJS40 is aimed at drivers who frequently travel in remote areas, own larger gasoline or up to 10.0L diesel vehicles, or who want a single compact device that combines a high-capacity jump starter with multiple charging ports. It is useful for tradespeople, RV and boat owners and anyone who needs to run 15V DC accessories such as inflators and small refrigerators.

Those who should look elsewhere include buyers who prioritize the absolute lightest or smallest pocket-sized jump starters or who need extreme long-term runtime for continuous power tasks beyond the stated 88.88Wh capacity; professional tow fleets that require industrial-grade units with much higher amp-hour reserves may prefer specialized equipment.

Pros & Cons

Pros

• Very high peak current that handles large engines and multiple consecutive jump starts from one charge.
• Smart DSLI IV control increases output voltage and protects against overheating during starts.
• Multiple charging ports and a DC output broaden its use beyond emergency starts.
• Durable ABS body with an integrated LED light is convenient for roadside use.

Cons

• Some customers report mixed opinions on long-term battery life and occasional questions about build quality compared with premium industrial units.
• The unit is larger and heavier than ultra-compact jump packs, which affects pocketability.

Specifications

Peak Current	4120A
Battery Capacity	24000mAh (88.88Wh)
Supported Engines	All gasoline and up to 10.0L diesel engines
Operating Temperature	-4F to 140F
Output Ports	USB 5V/2.4A, USB QC 5/9/12V, Type-C 5V/3A, DC 15V/10A
Build Material	Fire-proof ABS, rain/dust/drop resistant
Included Accessories	Jumper clamps, USB-C cable, cigarette adapter, carrying case, manual

Our Verdict

The YESPER YJS40 balances high starting power, honest battery capacity, and useful accessory outputs to deliver solid value for drivers who need a reliable emergency starter and a multiport power station. It is especially sensible for owners of larger gasoline and diesel engines who want a durable, feature-rich jump box without paying for industrial-grade extras.

Frequently Asked Questions

Can this starter jump a diesel truck?
Yes, it is rated to start diesel engines up to 10.0L and is designed to handle large gasoline engines as well.

How many jump starts per charge can it do?
The unit can achieve about 60 jump starts on a single charge under typical conditions, depending on temperature and usage.

Does it power devices other than starting a car?
Yes, it has USB, QC USB, Type-C and a DC 15V/10A port to run inflators, fridges and charge phones or other electronics.