Pure-Electric Retrofit for 6-Ton Excavators: Diesel-to-Electric Conversion Solut

November 07,2026

65 kW permanent-magnet synchronous motor + five-in-one controller + 100 kWh battery

Revive the old machine, cutting both cost and emissions with pure electricity

As the dual-carbon goal enters the construction-machinery agenda, as China's National Stage IV non-road emission standard takes full effect, and as urban utility tunnels, indoor demolition and night work grow ever more sensitive to noise and exhaust—electricity is becoming the new answer for small-excavator power. But we need not scrap a still-working old digger. This article uses a 6-ton excavator as an example to introduce a mature pure-electric retrofit solution: remove the diesel engine and fit a water-cooled new-energy 65 kW permanent-magnet synchronous motor, a five-in-one controller and a new-energy cooling/heating A/C unit, with a 100 kWh traction battery (expandable by available space), giving the old machine a pure-electric new life.

Background: why retrofit even a 6-ton mini excavator

· Emission and environmental pressure: with Stage IV and stricter standards, diesel exhaust and particulates are especially acute in cities, indoors and tunnels.

· Operating cost: diesel prices are volatile and stay high; mini excavators each burn little, but the installed base is huge and usage frequent, so it adds up.

· Changing duty cycles: urban utility tunnels, indoor renovation/demolition, beautiful-countryside construction and night work increasingly demand low noise and zero exhaust.

· New-machine cost barrier: same-tonnage pure-electric new machines cost markedly more than diesel versions—a heavy outlay for owner-operators and small rental firms.

What retrofitting means: not scrapping, but extending life + upgrading

· Reuse the old machine: the undercarriage, hydraulics and structure are intact; only the 'heart' is swapped, avoiding the waste of scrapping the whole machine.

· Direct cost cut: electricity replaces diesel, sharply lowering per-unit energy cost.

· Green compliance: zero exhaust, easily passing environmental checks and enclosed/semi-enclosed duty.

· Quiet operation: motor noise is far below diesel, so night and residential work no longer disturb neighbors.

· Asset value retention: pure-electric attributes raise resale value and rental competitiveness.

· Longevity and less consumption: the motor is simple, with no reciprocating wear, so maintenance items and failure points drop sharply.

Pure-electric solution overview: one removal, one install—diesel engine becomes motor

Core idea: remove the original diesel engine and accessories, and fit three major components—

· A water-cooled new-energy 65 kW permanent-magnet synchronous main drive motor.

· A five-in-one controller (integrating main/auxiliary drive and A/C heating/cooling control, and charging the 24V battery).

· A new-energy cooling/heating A/C integrated unit.

· A vehicle VCU controller.

The whole system keeps the original hydraulics and undercarriage; the vehicle architecture is essentially unchanged, so retrofit risk is controlled and the cycle is short.

Core three-electric and system configuration

1. Main drive motor: water-cooled new-energy 65 kW permanent-magnet synchronous motor

· Permanent-magnet synchronous structure is efficient with high low-speed torque, matching the excavator's frequent start-stop and variable-load duty.

· Water cooling keeps temperature rise controllable for long continuous work.

· Rated 65 kW / peak 130 kW fully meets the digging, swing and travel power needs of a 6-ton class.

2. Five-in-one controller: one unit, many controls, and it charges the battery

· Integrates motor drive, auxiliary control, DC-DC and A/C control, greatly simplifying wiring.

· Built-in DC-DC draws from the high-voltage battery to continuously charge the 24V battery—the original 24V electrical system (lights, instruments, solenoids) needs no change.

· Unified first-tier brand control logic gives good vehicle matching and fewer failure points.

3. New-energy cooling/heating A/C integrated unit

· Cooling comes from the new-energy unit replacing the original compressor; heating uses PTC electric coolant heating, fully reusing the original A/C lines, radiator and cab controls—reliable and stable.

· Automotive-grade reliability, integrated cooling and heating, comfortable cab in all seasons.

4. Traction battery: 100 kWh to start, expandable by space

· Standard 100 kWh battery, 5–8 h range covering medium-short shifts / intermittent work.

· If engine-bay or counterweight space allows, the battery can be further expanded for longer daily range and longer continuous work.

· Pure-electric solution, just plug in to charge—no diesel, no cable-feed truck.

Retrofit key points: in-situ replacement, unchanged architecture

· ① Power replacement: remove engine and accessories, install the main drive motor and five-in-one controller in place.

· ② Reuse cooling: keep the original cooling system; the motor/controller water-cooling loop is independent or shared, keeping temperature rise controllable.

· ③ 24V supply: the five-in-one controller's DC-DC charges the 24V battery—zero change to the original low-voltage electricals.

· ④ A/C structure untouched: the cooling/heating unit connects to the original lines; the cab interior is unchanged.

· ⑤ Vehicle architecture unchanged: the three-electric assembly is laid out in place—easy to remove/install, high reuse, low risk.

One-line summary of advantages

· Pure-electric, zero exhaust—green compliant, worry-free in enclosed/indoor duty.

· Low noise and quiet—no disturbance to night or residential work.

· Significant cost cut—electricity replaces diesel, slashing per-unit energy cost.

· Integrated control—five-in-one controller with automatic 24V charging.

· In-situ retrofit—unchanged architecture, short cycle, low risk, high reuse.

· Expandable battery—100 kWh to start, expand range as needed.

Versus a pure-electric new machine: the unique value of retrofitting

Many ask: can't I just buy a pure-electric new machine? For the 6-ton class, diesel-to-electric often gives better value:

In one line: a pure-electric new machine is buying a new house, while diesel-to-electric is a fine renovation of the old one—just as comfortable to live in, but far lighter on the wallet.

08 Conclusion

Diesel-to-electric is not throwing away the old machine, but letting it keep working longer in a cleaner, cheaper and quieter way. This pure-electric solution for the 6-ton excavator—65 kW permanent-magnet synchronous motor + five-in-one controller + new-energy cooling/heating A/C unit + 100 kWh (expandable) battery—brings pure-electric new-machine capability to the equipment you already own, through in-situ replacement with low risk and low cost.

If you have a 6-ton excavator and are considering electrification, contact us for a tailored retrofit plan and quote.

Source : www.51cm.org

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Tags : Hebei Komatsu diesel-to-electric excav