AVIakku 3.6V Li-ion Battery (4R25) — the smart alternative to 6V batteries.

Rechargeable, long-lasting, and fully compatible with all 6V construction warning lights — over 80 days of runtime, very low self-discharge, and 1,000+ charge cycles.

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Longer runtime with AVIakku
CO₂e savings: 4.5 t/yearCompatible with 6V warning and signal lights that use 4R25 batteries.
AVIakku is more cost-effective in the long run than disposable 4R25 batteries.

Industry leaders trust AVIALP.

Brand Shape Brand Shape

2-5 X

Fewer swaps

Depending on the model, one 4R25 battery runs for 60–100 days instead of ~20 days with a disposable 4R25 battery — reducing battery swaps by a factor of 2 to 5.

> 90%

lower operating costs

In real use, one 4R25 battery replaces more than 1,000 disposable 4R25 batteries and cuts your battery costs by well over 90%.

> 99%

less waste

Instead of disposing of hundreds of disposable 4R25 batteries, you use a single rechargeable 4R25 battery — reducing battery waste by more than 99% and helping protect the environment.

AVIakku 4R25 - rechargeable 3.6V Li-ion battery for 6V construction warning lights

Longer runtime, lower costs, full compatibility.

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3.6V Li-ion with BMS — stable voltage from 4.2V to 2.6V

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Very low self-discharge thanks to Li-ion technology

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Fully compatible with 6V construction warning lights

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AVIakku 25Ah Runtime

Up to 60 days (steady-on).
Up to 120 days (flashing mode).

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AVIakku 45Ah Runtime

Up to 110 days (steady-on).
Up to 220 days (steady-on).

AVIAkku 25Ah 4R25 Li-ion battery — €49.99
AVIAkku 45Ah 4R25 Li-ion battery — €79.99
AVIcharger — charger for AVIAkku 4R25 3.6V Li-ion batteries — €89.99.

AVIcharger - 4R25 Li-ion battery charger

Smart charger for the 3.6V AVIakku 4R25 (25Ah and 45Ah). Designed for maximum lifespan, safety, and efficient charging of 6V construction warning light batteries.

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Charges up to 3 batteries in parallel — optimized for gentle charging

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Built-in temperature monitoring — protects against overheating

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Plug & play — ready to use, no separate power supply required

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10h charging time for 3× 25Ah AVIakku

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20h charging time for 3× 45Ah AVIakku

Certified to IEC 62133-2 and UN 38.3

Our products aren’t just developed — they’re independently tested. Both the battery and the charger meet all relevant international safety and quality standards.

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4R25 Li-ion battery

Why 3.6V works in 6V lights.

Lab rating vs. real-world use.

The “6V” on disposable 4R25 batteries is a lab rating. On site, the voltage drops sharply under load within a short time.

Fast voltage drop.

After only brief use, conventional 4R25 batteries drop to 4–5V, later to 3–4V, and near the end even close to 0V — with noticeably reduced performance.

A wide operating range is required.

That’s why construction warning lights are designed to work across a wide voltage range — otherwise disposable 6V 4R25 batteries would only be reliable at the very beginning.

Fully compatible with 3.6V Li-ion.

The 4R25 AVIakku delivers a stable voltage from 4.2V down to 2.6V — matched to the real operating window of modern warning lights.

Under load, a “6V” disposable 4R25 drops significantly. Construction warning lights are designed to operate across a wide voltage range — making the 3.6V Li-ion AVIakku compatible.

What customers say about AVIakku.

Why 100+ companies choose the rechargeable 4R25 battery.

“Runtime and cost are what matter most to us. We searched for a long time for a solution that truly meets these requirements. With AVIakku, we finally found a reliable and cost-effective option — one that exceeds our expectations.”

“With 60+ days of battery life and the ability to recharge the batteries over 1,000 times, AVIakku has significantly improved our efficiency. It saves time and money — and also reduces our environmental footprint.”

"As a small company, we often deal with short-term job sites. AVIakku is the perfect alternative — we don’t have to keep buying new batteries for one-week projects."

Frequently asked questions.

Everything you need to know about the rechargeable 4R25 AVIakku.

What are the key benefits — why switch to AVIakku?
Do 6V construction warning lights work with the 3.6V Li-ion AVIakku?
How much does AVIakku cost?
When does AVIakku become cheaper than disposable batteries?

4R25 rethought — recharge instead of throw away

AVIALP builds rechargeable 4R25 batteries that eliminate the hidden costs and safety risks of disposable batteries used in construction warning lights. With 2–3× longer runtime, 1,000+ charge cycles, and very low self-discharge, AVIALP delivers longer operating time, less waste, and lower total cost over time.

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Construction warning light with an installed AVIAkku 4R25 Li-ion battery