Every used-truck negotiation is a negotiation about information. In diesel trucks the information hides in oil samples and maintenance books; in electric trucks it sits in the battery — and unlike a diesel engine, the battery keeps a complete, tamper-evident record of its own life. State of Health (SOH) diagnostics is the discipline of reading that record and turning it into money: warranty claims that pay out because they are documented, resale prices that hold because they are certified, and second-life battery transactions that price honestly. This guide explains the diagnostics as we deliver them for fleets operating models like the KTH1 electric cargo truck, and connects to the market context in our Mexico electric truck market guide, where used-truck channels are already active.
SOH is not one number but a family of them, and knowing which one a document reports is half the diligence:
The BMS in every Dongfeng EV truck logs the full record continuously — cell voltages, temperatures, cycle counts, fault events — readable through the diagnostic port by our service software, and exportable as a signed report that a buyer or warranty administrator can trust:
| Diagnostic artifact | Contents | Used for |
|---|---|---|
| Annual SOH certificate | Capacity and resistance SOH, module spread, cycle count, temperature history | Warranty file, fleet asset register, finance-company reporting |
| Sale-time health report | Same data, stamped and dated at inspection | Used-truck transaction, lease return, insurance claim |
| Telematics trend extract | Rolling SOH trend over the fleet's life, not just a snapshot | Distinguishes healthy gradual ageing from a step-change event |
| Second-life assay | Module-level mapping for stationary-storage repurposing | Pricing the pack's value after truck service |
CATL LFP chemistry — the standard across our truck range — is warranted to 70–80% capacity at 8 years or 4,500 cycles. Field data shows typical fleet LFP packs holding 80–85% at five years of hard duty. The pricing structure that creates:
The certificate changes the negotiation because it converts the battery from an unknown into a number. Used diesel trucks in export markets trade on reputation and grease inspection; used electric trucks trade on documents — and a documented 82% SOH KTH1 will outsell an uncertified equivalent every time, because the buyer's risk is visible rather than infinite.
The 8-year / 4,500-cycle warranty covers capacity degradation below threshold and module defects. The claim mechanism is diagnostic, not rhetorical: the annual SOH certificate builds the evidence trail, and a pack crossing the degradation threshold at year six with a clean service history is a straightforward claim; the same pack without annual records risks disputes over abuse and duty-cycle history. The records that pay claims are the ones made before anything went wrong. This is why our maintenance schedule — covered in our preventive maintenance guide — builds the annual SOH pull into the routine service rather than leaving it to sale-time, when it is too late to shape the story.
Walk through how a documented SOH file changes an actual used-truck negotiation, because the mechanics are concrete. A buyer inspecting a five-year-old electric rigid without documentation faces an unpriced risk: the battery might be at 85% or at 65%, and the spread between those two trucks is tens of thousands of dollars — so the rational buyer prices the worst case, or walks. The same truck presented with its annual SOH certificates, the telematics trend line and the BMS export reads differently: the capacity figure, the resistance figure and the module spread are stated, dated and signed, and the buyer's risk premium collapses into a modest inspection margin. Across our export markets, the observable spread between documented and undocumented used electric trucks is already wider than the equivalent spread in used diesel — because the battery is a larger share of the asset's value than any diesel component, and the difference between a known and an unknown battery is therefore larger too.
Three practical habits turn this into fleet policy. Pull the annual certificate as maintenance, not as an exit event — the file builds itself. Watch the module-spread trend line, because a narrowing spread caught at year three is a balancing service, while the same spread discovered at sale is a discount. And match the truck's route to its SOH as it ages: the 75% pack that struggles on the long corridor is still the right truck for the short dense route, and a fleet that manages this matching internally captures the residual value that a fleet which simply de-fleets leaves on the table.
For finance partners, the same file underwrites the asset: leasing structures and residuals price against the certificate, and the annual pull is what makes the electric truck financeable on terms diesel never enjoyed — the machine documents its own remaining life.
Want battery health documentation for your fleet? Contact Shaanxi Fenghan Trading — authorized Dongfeng EV truck exporter. WhatsApp: +86 153 1943 1311 | Email: sales@fenghan-trade.com | dongfengevtrucks.com
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