Having trouble charging your Gen2.5 Battery? This guide covers common charging issues, including chargers that won't start, batteries stopping at 85%, the final 1–2% not charging, charger indicator lights and how to reset your smart charger.

Most charging and battery issues are simple to resolve and don&apos;t indicate a fault with your battery or charger. Gen2.5 batteries use a smart Battery Management System (BMS) and communicates with the smart charger before charging begins. This communication allows the battery and charger to perform safety checks before charging.This guide covers the most common charging issues, including charging interruptions, charger status lights, final charging percentage and battery state-of-charge readings.<h2 style="text-align: center;" id="isPasted">Charger Isn&apos;t Charging The Battery</h2>The 43V charger is a smart charger that communicates with the battery&apos;s Battery Management System (BMS) before charging begins. This &quot;handshake&quot; is a normal safety feature.Occasionally, if charging is interrupted (for example, the charger is unplugged while charging), the charger may not immediately restart when plugged back in.<h3 id="symptoms">Symptoms</h3><ul data-spread="false"><li style="font-size: 14px;">Charger remains solid green.</li><li style="font-size: 14px;">Battery does not begin charging.</li><li style="font-size: 14px;">Fan does not start.</li><li style="font-size: 14px;">Charger appears to have finished charging when it hasn&apos;t.</li></ul><h3 id="solution">Solution</h3><ol data-spread="false" start="1"><li style="font-size: 14px;">Disconnect the charger from power.</li><li style="font-size: 14px;">Wait 10&#x2013;15 seconds&#xA0;until:<ul data-spread="false" style="font-size: initial;"><li style="font-size: 14px;">the charger light turns completely off</li><li style="font-size: 14px;">you hear the internal relay click.</li></ul></li><li style="font-size: 14px;">Reconnect the charger to power.</li><li style="font-size: 14px;">Allow the charger and battery a few seconds to complete their handshake.</li><li style="font-size: 14px;">Charging should begin normally.</li></ol>When charging starts correctly you will notice:<ul data-spread="false"><li style="font-size: 14px;">the charging indicator begins flashing</li><li style="font-size: 14px;">the charger fan starts running.</li></ul>Tip:&#xA0;Around 99% of charging issues are resolved by fully power cycling the charger before reconnecting it.<h2 style="text-align: center;" id="charger-flashing-red-and-green">Charger Flashing Red and Green</h2>A flashing red and green indicator typically means charging was interrupted unexpectedly, such as unplugging the charger while it was actively charging.This is simply a charger status indication and is easily resolved.<h3 id="to-reset">To reset:</h3><ol data-spread="false" start="1"><li style="font-size: 14px;">Unplug the charger.</li><li style="font-size: 14px;">Wait until all lights have turned off.</li><li style="font-size: 14px;">Plug the charger back in.</li></ol>The charger will reconnect to the battery and resume charging normally.<h1 style="text-align: center;" id="isPasted">Why Won&apos;t My Battery Top Up the Last 1&#x2013;2%?</h1>Gen2.5 batteries use intelligent charging logic.If your battery is already very close to full, the charger may determine that the charging cycle has already been completed and may not restart for the final 1&#x2013;2%.This is completely normal.Once the battery reaches approximately 50V, it is effectively fully charged. Although the battery can reach around 50.4V, the additional runtime gained is only a matter of seconds and is not worth repeatedly attempting to achieve.If you&apos;re unsure whether charging has completed:<ol data-spread="false" start="1"><li style="font-size: 14px;">Unplug the charger.</li><li style="font-size: 14px;">Wait for it to power down.</li><li style="font-size: 14px;">Plug it back in.</li></ol>If charging resumes, the battery will top itself up. If not, the battery is already considered fully charged.<h2 id="isPasted" style="line-height: 2; text-align: center;">Battery Not Charging Beyond 85%</h2>Some early-release Gen2.5 chargers may prevent the battery from charging beyond approximately 75%-85%.This is a&#xA0;charger firmware issue and can be resolved with a firmware update.If your battery consistently stops charging at around 85%:<ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Contact the&#xA0;Foil Drive Support Team.</li><li style="font-size: 14px; line-height: 2;">Send a&#xA0;video showing the battery, charger and charging behaviour, including the charger indicator lights.</li><li style="font-size: 14px; line-height: 2;">Our support team will assess the issue and determine the most appropriate resolution based on your location.</li></ol>Depending on your location and circumstances, the resolution may be:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">A&#xA0;replacement charger being sent to you, with your current charger returned to a Foil Drive service centre for a firmware update.</li><li style="font-size: 14px; line-height: 2;">Your existing charger being updated with the latest firmware and returned to you.</li></ul>Do not assume the battery is faulty if it will not charge beyond 85%. Early-release chargers affected by this issue can be resolved through a charger firmware update.Foil Drive Support will assess each case individually and confirm the appropriate process for your location.<h2 id="isPasted" style="text-align: center;">Check You&apos;re Using the Correct Charge Mode</h2>If charging stops immediately after starting, check whether you&apos;ve selected Storage Charge.Storage Charge will stop automatically once the battery reaches the correct storage voltage.If your battery is already above storage level, charging won&apos;t begin.This is normal behaviour.<h1 id="isPasted" style="line-height: 2; text-align: center;">Still Having Charging Issues?</h1>If your Gen2.5 battery or 43V charger is still not operating correctly after completing the troubleshooting steps above, contact Foil Drive Support for assistance.

Gen2.5 – Charging Troubleshooting

Learn how to care for your Gen2.5 Battery and troubleshoot common issues, including battery removal, unexpected charge loss, incorrect battery percentage readings and water ingress.

This article covers common Gen2.5 Battery questions, troubleshooting tips and best practices to help you get the most from your battery and keep it performing at its best.For instructional video, see:&#xA0;<a href="https://www.youtube.com/watch?v=OiUmQ6uuGDk" target="_blank" rel="noopener noreferrer">Gen2.5 Battery Tips</a><h3 id="isPasted" style="line-height: 2; text-align: center;">Battery Loses 1&#x2013;2% While Sitting</h3>You may notice that a fully charged battery loses a small amount of charge after sitting unused for several days.This is normal.The Gen2.5 Battery has an active&#xA0;BMS and Bluetooth system, which consume a very small amount of power while the battery is sitting.The battery may therefore drop by a small percentage over time.If you&apos;re only trying to top up the final 1&#x2013;2%, the charger may consider the battery already fully charged and not restart the charging cycle.<h1 id="isPasted" style="line-height: 2; text-align: center;">Battery Difficult to Remove</h1>Some board and mast combinations can place additional compression on the battery, making it slightly harder to remove.This can happen because different boards and mast systems vary in shape, stiffness and surface area.If this happens:<h3 style="line-height: 2;" id="method-1--use-the-battery-latches-for-leverage">Method 1 &#x2013; Use the Battery Latches for Leverage</h3><ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Open both battery latches.</li><li style="font-size: 14px; line-height: 2;">Place your thumbs inside the latch recesses.</li><li style="font-size: 14px; line-height: 2;">Hold the latches with your fingers.</li><li style="font-size: 14px; line-height: 2;">Use the latches to gently push the battery away from the unit.</li></ol>This provides much better leverage than simply trying to pull the battery straight out.<h3 style="line-height: 2;" id="method-2--reduce-compression">Method 2 &#x2013; Reduce Compression</h3>If the battery is still difficult to remove, slightly loosen the&#xA0;front mast bolts by one or two turns.Reducing the compression can allow the battery to slide out more easily.Important: Only loosen the bolts enough to release the compression. Do not operate the system with the mast bolts loose.This issue is generally related to the specific combination of board, mast and Foil Drive installation rather than a fault with the battery.For instructional video, see:&#xA0;<a href="https://youtu.be/I1zc4c-kg_c" target="_blank" rel="noopener noreferrer">Removing Battery from Housing Tip</a><h1 style="text-align: center;" id="isPasted">40V Battery Checker Shows the Wrong Percentage</h1>The original Gen 2 inline battery checker is not compatible with 43V batteries.Gen2.5 batteries use a higher battery voltage, the older checker will display an incorrect state of charge.Instead, check battery percentage using one of these methods:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">The Battery Caddy</li><li style="font-size: 14px; line-height: 2;">The Foil Drive App</li><li style="font-size: 14px; line-height: 2;">The Foil Drive unit when connected</li></ul>These methods provide the correct battery state-of-charge information for Gen2.5 Batteries.<h1 id="isPasted" style="line-height: 2; text-align: center;">My Battery Got Wet</h1>If water enters the battery compartment, don&apos;t panic.The most important thing is to&#xA0;remove the water, dry the connectors and protect them from corrosion before continuing to use the system.The battery and unit are designed to be waterproof, but the electrical connectors require particular care.<h2 style="line-height: 2; text-align: center;" id="if-salt-water-entered-the-unit">If Salt Water Entered the Unit</h2>Salt water should be removed as soon as possible because salt residue can accelerate corrosion and damage electrical terminals.<ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Remove the battery.</li><li style="font-size: 14px; line-height: 2;">Drain all water from the unit.</li><li style="font-size: 14px; line-height: 2;">Rinse the battery compartment thoroughly with fresh water to remove any salt residue.</li><li style="font-size: 14px; line-height: 2;">Allow the unit to drain and dry.</li><li style="font-size: 14px; line-height: 2;">Dry the battery connector thoroughly.</li><li style="font-size: 14px; line-height: 2;">Inspect the terminals for any signs of corrosion.</li></ol><ol data-spread="false" start="1" id="isPasted"><li style="font-size: 14px; line-height: 2;">Once dry, reapply&#xA0;Foil Drive dielectric grease to the battery terminals.</li><li style="font-size: 14px; line-height: 2;">Allow everything to dry before reinstalling the battery.</li></ol>Do not continue operating the system with salt water sitting inside the unit or on the electrical connectors.<h3 style="line-height: 2; text-align: center;" id="if-fresh-water-entered-the-unit">If Fresh Water Entered the Unit</h3>Fresh water is much less of a concern.Simply:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Remove the battery.</li><li style="font-size: 14px; line-height: 2;">Drain the water.</li><li style="font-size: 14px; line-height: 2;">Allow the compartment to dry.</li><li style="font-size: 14px; line-height: 2;">Dry the battery connector.</li><li style="font-size: 14px; line-height: 2;">Reapply Foil Drive dielectric grease.</li><li style="font-size: 14px; line-height: 2;">Reinstall the battery once everything is dry.</li></ul><h2 id="isPasted" style="line-height: 2; text-align: center;">Battery Damaged by Water or Impact</h2>If there is any damage to the&#xA0;battery heat shrink, outer casing or connector, do not use or attempt to charge the battery.Contact the Foil Drive Support Team at <a href="mailto:support@foildrive.com">support@foildrive.com</a> with clear, detailed photos of the battery so we can assess the damage.<h1 id="isPasted" style="line-height: 2; text-align: center;">Preventing Water Ingress</h1>If you&apos;re regularly finding water inside the unit, there are several things to check:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Ensure the&#xA0;O-ring is correctly installed.</li><li style="font-size: 14px; line-height: 2;">Check that the O-ring is clean and free from sand, dirt or debris.</li><li style="font-size: 14px; line-height: 2;">Check that the battery latches are correctly fitted and in good condition.</li><li style="font-size: 14px; line-height: 2;">Check for damage to the unit or sealing surfaces.</li><li style="font-size: 14px; line-height: 2;">Check that your board is sufficiently rigid for the Foil Drive installation.</li></ul><h3 style="line-height: 2;" id="board-flex">Board Flex</h3>Some boards may flex significantly under load.If the board is too flexible, the movement of the board can place additional forces on the more rigid Foil Drive unit. During impacts or landings, this movement can momentarily affect the seal and allow water to enter the battery compartment.If you&apos;re experiencing repeated water ingress, check the rigidity and compatibility of your board and Foil Drive setup.<h1 id="isPasted" style="line-height: 2; text-align: center;">Need More Help?</h1>If you&apos;ve worked through these troubleshooting steps and are still experiencing battery issues, please contact the&#xA0;Foil Drive Support Team.When contacting support, include:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Your Gen2.5 Battery model</li><li style="font-size: 14px; line-height: 2;">A description of the issue</li><li style="font-size: 14px; line-height: 2;">Photos showing the battery and connectors where relevant</li><li style="font-size: 14px; line-height: 2;">A video showing the charger behaviour and indicator lights, if the issue is related to charging</li></ul>This information will help our support team diagnose the issue as quickly as possible.

Gen2.5 - Battery Troubleshooting

Learn how to test the voltage output of your Foil Drive charger, battery and BMS using a multimeter. This guide covers voltage testing across our battery and charger range and can help identify potential charging or battery issues.

This guide explains how to test the voltage of your Foil Drive battery, charger and Battery Management System (BMS) using a multimeter.The process can be used across the Foil Drive battery range, including Assist, Assist PLUS, Gen2 and Gen2.5, as well as compatible 28V and 40V chargers.Voltage testing can help identify potential issues with the charger, battery or BMS when the charging system is not behaving as expected.<h2 id="isPasted" style="line-height: 2; text-align: center;">Potential Charging Faults</h2>This test may be useful if you experience symptoms such as:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">The charger is connected to mains power and displays a solid green light, but remains green when connected to a drained battery.</li><li style="font-size: 14px; line-height: 2;">The charger displays a flashing green light when connected to the battery.</li><li style="font-size: 14px; line-height: 2;">The battery does not appear to be charging as expected.</li></ul><h2 style="line-height: 2; text-align: center;" id="instructional-videos">Instructional Videos</h2><a href="https://www.youtube.com/embed/mLjH-uvZLK8" target="_blank" rel="noopener noreferrer">Gen2 Battery - Voltage Testing</a><a href="https://www.youtube.com/embed/ZuEuU5yMvYs" target="_blank" rel="noopener noreferrer">Assist PLUS Charger &amp; Battery - Voltage Testing</a><h2 style="line-height: 2; text-align: center;" id="what-youll-need">What You&apos;ll Need</h2><ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Multimeter</li><li style="font-size: 14px; line-height: 2;">Foil Drive charger</li><li style="font-size: 14px; line-height: 2;">Foil Drive battery</li><li style="font-size: 14px; line-height: 2;">Small paper clip or similar item, if required to access the BMS test point</li></ul><h2 id="isPasted" style="line-height: 2; text-align: center;">Safety</h2>Take care when testing battery and charger voltage.Ensure the multimeter is set correctly to DC voltage before testing.Do not allow the positive and negative terminals to contact each other, and take care not to short the battery terminals with the multimeter probes or any other object.If you are unsure about performing these tests, contact Foil Drive Support for assistance.Gen2 Batteries<h3 id="isPasted" style="line-height: 2;">Set your multimeter to DC voltage (V&#x2393;).</h3>Depending on the multimeter, this may be represented by:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">V with a solid line and dotted line underneath &#x2014; DC voltage</li><li style="font-size: 14px; line-height: 2;">V with a wave symbol (~) &#x2014; AC voltage</li></ul>Make sure you select DC voltage, not AC voltage.If your multimeter requires you to select a voltage range, choose a range that can measure at least 40 V DC. A 40 V battery can measure above 40 V when fully charged, so do not select a range that is too low.<h3 style="line-height: 2;" id="isPasted">Testing the Battery Voltage</h3><ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Locate the two large battery terminals.</li><li style="font-size: 14px; line-height: 2;">Place the red probe on one terminal.</li><li style="font-size: 14px; line-height: 2;">Place the black probe on the other terminal.</li><li style="font-size: 14px; line-height: 2;">Make sure the probes remain separated and do not touch each other.</li><li style="font-size: 14px; line-height: 2;">Ensure the probe tips are making good contact with the sides of the terminals.</li></ol>A correctly charged 40V battery should show a voltage reading appropriate to its current state of charge.For example, the battery shown in the instructional video measures approximately 39.7 V.<h3 style="line-height: 2;" id="if-the-reading-is-negative">If the Reading is Negative</h3>Don&apos;t worry if your multimeter displays a negative voltage.This simply means the probes are connected in the opposite orientation.For example:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Red probe on positive / black probe on negative = +39.7 V</li><li style="font-size: 14px; line-height: 2;">Red probe on negative / black probe on positive = &#x2212;39.7 V</li></ul>The voltage value is the same; only the polarity has changed.Important: Take care when positioning the probes. Do not allow the positive and negative probes to touch each other, as this can short the battery terminals.<h1 style="line-height: 2; text-align: center;" id="assist-and-assist-plus-batteries">Assist and Assist PLUS batteries</h1><h1 id="isPasted" style="line-height: 2;">Testing Battery Voltage</h1><ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Set your multimeter to DC voltage (V&#x2393;).</li><li style="font-size: 14px; line-height: 2;">Place the red probe on the battery positive (+) terminal.</li><li style="font-size: 14px; line-height: 2;">Place the black probe on the battery negative (&#x2212;) terminal.</li><li style="font-size: 14px; line-height: 2;">Record the voltage displayed.</li></ol>Important: Take note of the battery voltage reading. You will compare this with the BMS voltage in the next test.In the example shown in the instructional video, the battery measured approximately 27.98 V.<h1 id="isPasted" style="line-height: 2;">Testing BMS Voltage</h1>The BMS test allows you to compare the voltage being measured at the battery cells with the voltage being reported through the BMS circuitry.<ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Place the black multimeter probe into the small hole between the two larger holes on the connector.</li><li style="font-size: 14px; line-height: 2;">If your multimeter probe is too short to reach the contact, a small paper clip or similar item can be used to extend the probe.</li><li style="font-size: 14px; line-height: 2;">Place the red probe on the positive (+) terminal.</li><li style="font-size: 14px; line-height: 2;">Record the voltage displayed.</li></ol>Compare this reading with the battery voltage measured in the previous step.In the example shown in the video:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Battery voltage: 27.98 V</li><li style="font-size: 14px; line-height: 2;">BMS voltage: 27.98 V</li></ul>The matching readings indicate that the BMS voltage reading corresponds correctly with the battery cell voltage.If there is a significant difference between the battery voltage and BMS voltage, stop testing and contact Foil Drive Support for assistance.<h1 id="isPasted" style="line-height: 2;">Testing the Charger Output</h1><ol data-spread="false" start="1"><li style="font-size: 14px; line-height: 2;">Set your multimeter to DC voltage (V&#x2393;).</li><li style="font-size: 14px; line-height: 2;">Connect the charger to mains power.</li><li style="font-size: 14px; line-height: 2;">Place the red multimeter probe on the positive (+) output.</li><li style="font-size: 14px; line-height: 2;">Place the black multimeter probe on the negative (&#x2212;) output.</li><li style="font-size: 14px; line-height: 2;">Record the voltage displayed on the multimeter.</li></ol>For the charger shown in the instructional video, a reading of approximately 33.4&#x2013;34.7 V is within the expected output range.Note: Charger output voltage varies depending on the charger model. Always use the specifications applicable to the charger being tested.

How to Test Battery & Charger Voltage

Your 43V battery may display 100% State of Charge in the Foil Drive App or Battery Caddy while it remains connected to the charger. Learn why the battery can continue balancing and gently topping up after reaching 100%, and what this means.

<div data-block="true" data-editor="6bnr0" data-offset-key="6fs8r-0-0" id="isPasted">If you have a 43V Foil Drive Battery, you may notice that both the Battery Caddy and the Foil Drive App display 100% State of Charge while the battery remains connected to the charger and is still actively charging.This is completely normal and is part of how lithium battery charging and the Battery Management System (BMS) work.<h2 id="isPasted" style="text-align: center; line-height: 2;">Why does this happen?</h2>The Battery Management System (BMS) continuously estimates the battery&apos;s State of Charge using several factors, including:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Battery voltage</li><li style="font-size: 14px; line-height: 2;">Current flow</li><li style="font-size: 14px; line-height: 2;">Battery behaviour during charging and discharging</li></ul>As the battery approaches full charge, the charging process slows significantly to protect the battery and maximise its lifespan.Although the app may display 100%, the charger may still be:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">Balancing the individual battery cells</li><li style="font-size: 14px; line-height: 2;">Gently topping up the final portion of the battery&apos;s capacity</li></ul>This ensures every cell reaches the correct voltage before charging is complete.<h2 id="isPasted" style="text-align: center; line-height: 2;">A simple analogy</h2>Think of charging your battery like filling a car with fuel.Most of the fuel goes in quickly, but as the tank nears full, the fuel pump automatically clicking off when the tank is essentially full.If you&apos;ve ever gently squeezed the nozzle after the first click, you&apos;ll know you can often add a small amount more before the tank is completely full.Lithium batteries behave in a similar way.The Foil Drive App and Battery Caddy display 100% once the battery is effectively full for normal use, while the charger continues the final balancing and top-up process in the background.</div><h2 id="isPasted" style="text-align: center; line-height: 2;">Why doesn&apos;t the percentage keep increasing?</h2>The battery percentage is an estimate of usable charge rather than a direct measurement of every individual cell.Once the battery reaches its usable full capacity, the displayed State of Charge remains at 100%, even though the charger may still be performing the final balancing process.This is expected behaviour and does not indicate a fault with the battery, charger or Battery Caddy.<h2 id="isPasted" style="text-align: center; line-height: 2;">A closer look at your battery</h2>Unlike many battery-powered products that only display a simple percentage, the Foil Drive App provides detailed battery information, including:<ul data-spread="false"><li style="font-size: 14px; line-height: 2;">State of Charge (%)</li><li style="font-size: 14px; line-height: 2;">Total battery voltage</li><li style="font-size: 14px; line-height: 2;">Individual cell voltages</li><li style="font-size: 14px; line-height: 2;">Remaining amp-hours (Ah)</li><li style="font-size: 14px; line-height: 2;">Charging status</li><li style="font-size: 14px; line-height: 2;">Cell balancing information</li></ul>This provides a real &quot;look under the hood&quot; of what the battery is doing internally. Rather than simply showing Full or Empty, the app allows you to monitor the health and behaviour of the individual cells that make up the battery pack.<h2 id="isPasted" style="text-align: center; line-height: 2;">Is this normal?</h2>Yes.If your 43V battery shows 100% while it remains connected to the charger, this simply means the battery has reached its usable full capacity and the charger is completing the final balancing and top-up process.&#xA0;You can remove the battery from the charger once it reaches 100% charge, but if you&apos;re not in a rush, leave it connected to the charger to finish the final balance charge.&#xA0;

43V Battery Shows 100% While Still Charging

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Foil Drive

Having trouble charging or powering your Foil Drive Battery? Find troubleshooting guides for common battery and charger issues. Follow the recommended checks and solutions to help identify and resolve issues before contacting Foil Drive Support.