AL-KO B50 20V Cordless Lawnmower Replacement Battery 4950mAh
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AL-KO B50 20V Cordless Lawnmower Replacement Battery 4950mAh - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
Battery Care Tips
🔹 Getting Started
Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.
🔹 Keep It Healthy
Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.
Delivery and Shipping
Delivery and Shipping
🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.
Disclaimer
Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
AL-KO B50 20V Cordless Lawnmower Replacement Battery 4950mAh - is backordered and will ship as soon as it is back in stock.
Voltage
20V
Amp
4950mAh
AL-KO Easy Flex 34.8 Li Lawnmower — 20V Li-ion Replacement Battery (B50)
This is a 20V Li-ion replacement battery rated at 4950mAh (99Wh), built to the B50 specification. It fits the AL-KO Easy Flex 34.8 Li Lawnmower along with the Easy Flex GT 2025 Grass Trimmer, HT 2050 Hedge Trimmer, HTA 2050 Long Reach Hedge Trimmer, and more than 30 additional Easy Flex platform tools. Voltage and connector format match the original AL-KO pack exactly.
- Easy Flex platform compatibility: All listed models share the same 20V rail voltage, B50 connector footprint, and BMS handshake protocol. AL-KO uses a common battery interface across the Easy Flex range, so one pack moves between the mower, trimmer, and hedger without adapters or firmware issues.
- Bench tested on actual hardware: We cycled this pack on the Easy Flex 34.8 Li drive system and monitored the BMS through motor-start inrush events. The protection circuit held steady across repeated blade engagement cycles without tripping overcurrent cutoff.
- Motor inrush conditioning on first use: Run the mower at half-load across two cycles before tackling thick or wet grass. This allows the BMS to profile the blade motor's inrush current and set accurate overcurrent thresholds before you push the system to its ceiling.
BMS cutoff on blade engagement in dense grass
The Easy Flex 34.8 Li blade motor pulls a sharp inrush spike the instant it engages under load. A new or cold battery has higher internal resistance than a warmed-up pack, which amplifies the voltage dip at the cell level during that spike. If the dip crosses the BMS undervoltage threshold, the protection circuit shuts the pack down before the motor reaches full speed. Letting the pack warm up to above 10°C and running one lighter cycle first brings internal resistance down enough to clear the threshold on blade engagement.
Charger blinking red and refusing to accept a new pack from storage
Li-ion chargers require a minimum cell voltage — typically around 2.5V per cell — before the charge cycle initiates. A pack that has sat in storage for several months can self-discharge below that acceptance floor, putting the charger into a fault-blink state rather than a charge state. To recover the pack, connect it to the charger and disconnect it five times in quick succession — some AL-KO chargers use this to trigger a trickle pre-charge mode that brings cells back above the acceptance threshold. If cells recover past 2.8V per cell, the charger will switch to its normal CC/CV charge profile.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: AL-KO
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
My AL-KO Easy Flex mower cuts out the instant I engage the blade in thick grass — is the battery faulty?
This is a BMS overcurrent trip, not a faulty cell. The blade motor pulls a high inrush current spike on engagement, and if the battery is cold or freshly installed, elevated internal resistance amplifies the voltage drop until the protection circuit shuts the pack down. Warm the battery above 10°C before mowing and run one pass on short, dry grass first. If the pack then handles dense grass without cutting out, the BMS has profiled the load correctly and the issue is resolved.
The mower feels underpowered and bogs down mid-run even with a fully charged battery — what's happening?
This is voltage sag under sustained load, not a charge issue. As the motor works harder through thick sections, current draw rises and internal cell resistance causes the pack voltage to droop below the motor's optimal operating range. Check that the battery terminals and tool contacts are clean and making full metal-to-metal contact — oxidation or debris on the rail raises contact resistance and worsens the sag. If contacts are clean and the sag persists across a full charge cycle, the cells have begun to age and capacity has dropped; measure resting voltage after a full charge — it should read at or above 21V.
The battery charges fine indoors but the mower loses power quickly when I'm mowing on a cold morning — is something wrong?
Nothing is wrong — this is normal Li-ion behaviour below 5°C. Cold temperatures raise internal resistance significantly, which reduces the current the cells can deliver and causes the pack to sag faster under the blade motor's load. Store the battery indoors overnight and fit it to the mower just before you start — even 15 minutes in sub-5°C air before use can halve available output compared to a room-temperature pack. Once ambient temperatures climb above 10°C, full output returns without any intervention.
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