CarCareTruth Score
Decent.
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Prices may varyThis product ranks #10 of 20 in Jump Starter.Three above it ↓
Last reviewed June 21, 2026
TL;DR No third-party certification (CE, FCC, RoHS, UN38.3 only · no UL or ETL listing confirmed). Claims 4000A peak; the label figure has not been independently verified. Battery chemistry unspecified, treated as standard Li-ion. No active CPSC recall as of 2026-06-20 (CPSC database access was unavailable at time of review · verify manually at cpsc.gov before purchase). Standout feature: 65W USB-C bidirectional charging · one of the fastest charge rates in this category.
The RJ4000 is a 12V jump starter that claims 4000A peak for gas and diesel engines up to 10L. The 4000A figure is a label claim · no confirmed independent bench measurement was found at time of review. The unit carries FCC, CE, RoHS, and UN38.3 certifications; no UL or ETL third-party lab listing was found. Battery chemistry is not disclosed on the product page; cell voltage math (88.8Wh / 24Ah = 3.7V nominal) is consistent with standard Li-ion or LiPo, not LFP. The IP64 water and dust resistance is a real differentiator for a trunk-stored emergency device. The 65W USB-C bidirectional port stands out in this category · it charges the unit fully in 1.3 hours and outputs laptop-level power for stranded charging. Community data is limited to the rexing.com product page, which reflects very few reviews at time of this writing.
Good fit for drivers who want a well-featured emergency device with fast USB-C charging and IP64 durability and are comfortable with CE-only certification. The 65W USB-C output is genuinely useful as a travel power bank. Skip it if you need confirmed UL or ETL certification, require independent cranking verification for a large diesel engine, or prefer a brand with deep community track record and long-term owner data.
No UL or ETL certification confirmed as of 2026-06-20 · CE marking only. Battery chemistry is not disclosed by the manufacturer; standard Li-ion handling and disposal precautions apply. No active CPSC recall found, though the database was inaccessible for automated verification · confirm at cpsc.gov before purchase. Lithium batteries are recyclable via Call2Recycle drop-off locations (Home Depot, Lowe's, Best Buy). RoHS compliance limits hazardous substances in the device materials.
The 4000A figure is a label claim. No independent bench measurement from a third-party reviewer (such as Project Farm) was found for the RJ4000 at time of this review. Community reviews on rexing.com are broadly positive but limited in number. The cranking performance score is capped at 6.5 per the rubric rule for ultra-high-claim units without independent bench verification.
No UL or ETL listing was found for the RJ4000. The unit carries FCC, CE, RoHS, and UN38.3 certifications. CE marking indicates EU market conformity testing but is not equivalent to UL or ETL third-party lab certification. Buyers who require a lab-certified unit should consider UL-confirmed alternatives.
The 65W USB-C port works both ways · it charges the RJ4000 itself from a 65W USB-C source (filling the 24000mAh battery in about 1.3 hours), and it outputs up to 65W to charge phones, tablets, and laptops while you are on the road. The QC3.0 USB-A port also handles phone charging independently.
Rexing rates the RJ4000 for diesel engines up to 10L. The product page spec graphic shows 9L diesel in one place and 10L in another · this discrepancy is noted in the editorial record. For large diesel trucks (6.7L+ Cummins, Duramax, PowerStroke), the 4000A peak claim would need to be independently verified before relying on it.
The RJ4000 is sold directly through rexing.com. No Amazon listing was found as of the date of this review.
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