FAQ
TL;DR: Converting an 18V Einhell can work with a 160 VA transformer and 50 A bridge; "The downside is that it's heavy and a little buzzing." For lighter tasks, a laptop PSU may suffice. This FAQ helps DIYers who lost batteries power their tools safely. [Elektroda, czesiu, post #17219223]
Why it matters: You avoid unsafe mains hacks, choose workable specs, and keep a good drill running without hunting obsolete batteries.
Quick Facts
- Laptop PSU option: 18.5 V, 4.9 A Compaq PPP012L worked with 5 m of 2×1.5 mm² cable and 8×1000 µF/40 V caps. [Elektroda, nostromo, post #17215136]
- Transformer route: 24 V 160 VA safety transformer + 50 A bridge + 1000 µF cap; heavy and hums, but robust. [Elektroda, czesiu, post #17219223]
- Safety first: Do not retrofit a mains motor or triac regulator into a DC drill; “In no case.” [Elektroda, retrofood, post #17218773]
- Re‑cell alternative: High‑current 18650s 4s2p = 16.8 V; ~10 A cells ~PLN 4.99, 20 A < PLN 7 each. [Elektroda, marian paszek, #17219404]
- Regeneration path: Services can refit better‑than‑factory cells; ordering ready cell packets is also feasible. [Elektroda, Szyszkownik Kilkujadek, #17225561]
Can I power my 18V Einhell drill with a laptop power supply?
Yes. One working setup used a Compaq PPP012L brick rated 18.5 V, 4.9 A. The builder placed eight 1000 µF/40 V capacitors in the battery shell and ran a 5 m, 2×1.5 mm² cable. This kept the supply compact and the tool usable for home tasks. Use thick cable and solid connections for fewer voltage drops. [Elektroda, nostromo, post #17215136]
Is 19 V 4.7 A enough current for an 18 V drill?
It can spin the motor, but it may stall on tougher jobs. As one expert put it, “Maybe it will start ...”. Expect current limiting if you drive long screws or hole saws. Choose a higher‑current supply or a transformer build for headroom and reliability. [Elektroda, jack63, post #17218793]
Why pick a 160 VA transformer instead of a ~90 W laptop brick?
Transformers tolerate surge and short‑term overload better. One user contrasted a 160 VA setup with laptop adapters. “Laptop power adapters have 50–100 W.” Drills draw high peak power at startup and when near stall. The transformer approach held up better for heavy tasks, at the cost of weight and hum. [Elektroda, jack63, post #17219269]
What rectifier and capacitor values worked in practice?
A 50 A bridge rectifier handled the peaks. A 1000 µF electrolytic across the DC rails stabilized the trigger regulator. Without the capacitor the regulator misbehaved. “A 1000uF capacitor was necessary because the regulator without it did not work properly.” Expect a heavier, slightly buzzing unit with an iron‑core transformer. [Elektroda, czesiu, post #17219223]
How do I wire the transformer, bridge, and capacitor for DC output?
- Connect the transformer secondary to the AC inputs of a 50 A bridge rectifier.
- Install a 1000 µF electrolytic across the bridge’s + and – outputs.
- Run the DC outputs to the drill using a short, thick cable, observing polarity. [Elektroda, czesiu, post #17219223]
Can I just connect the drill to its original battery charger?
It usually fails under load. Chargers limit current for safe charging, not for driving motors. Users note laptop bricks around 50–100 W lag versus a 160 VA transformer that survives overload. Expect voltage sag or shutdown with a small charger. Use a higher‑power SMPS or a transformer‑bridge‑capacitor build. [Elektroda, jack63, post #17219269]
Is swapping in a blender motor and triac regulator a good idea?
No. “In no case. The screwdriver is not designed for mains voltage.” The switchgear and insulation are not rated for live mains. Keep the original DC motor and drive it from a proper DC source or rebuild the pack. That avoids shock hazards and premature failure. [Elektroda, retrofood, post #17218773]
What transformer voltage should I target for an 18 V drill?
One proven approach started from 24 V, 160 VA. The builder unwound several secondary turns to lower voltage, even reversing a few to trim it further. After rectification and a 1000 µF capacitor, the drill ran correctly. This gave durable torque but added weight and some hum. [Elektroda, czesiu, post #17219223]
What wire length and gauge have people used successfully?
A practical build used a 5 m cable of 2×1.5 mm². Thick conductors reduce voltage drop and keep the trigger responsive. The user also placed a weight in the battery shell to preserve balance. Keep leads as short as practical for better torque. [Elektroda, nostromo, post #17215136]
Can I place capacitors inside the old battery case?
Yes. One user fitted eight 1000 µF/40 V capacitors inside the pack shell for local energy storage. He also added a metal piece for weight to retain balance after removing cells. That setup ran from an 18.5 V, 4.9 A laptop adapter. [Elektroda, nostromo, post #17215136]
How do I rebuild with 18650 cells, and what will it cost?
Use a 4s2p pack for 16.8 V full charge. Choose high‑current cells rated 10–20 A. Example pricing: about PLN 4.99 per 10 A cell and under PLN 7 for 20 A types. Include a balancer connection and proper charging. You keep the tool cordless with familiar performance. [Elektroda, marian paszek, #17219404]
Do I need a special charger for 18650 packs?
Yes. “Laptop cells require a specific and dedicated charger.” Use a charger that balances series cells and follows lithium charge curves. Avoid charging lithium packs with the original Ni‑Cd/Ni‑MH charger. Proper charging preserves cycle life and safety. [Elektroda, nostromo, post #17222920]
Can a shop regenerate my original battery pack?
Yes. Users recommend regeneration services that replace worn cells with new ones, often better than stock. You can also order a ready packet that matches your pack layout and assemble it yourself. This restores cordless convenience without rewiring the tool. [Elektroda, Szyszkownik Kilkujadek, #17225561]
Where can I source used cells cheaply for a rebuild?
Ask power‑tool service centers, e‑waste points, or collection containers in construction hypermarkets. People discard worn packs there. You can sort cells and assemble a pack, though matching quality varies. Test and pair cells carefully if you go this route. [Elektroda, partyzancik, post #17227395]
