FAQ

Helium started out as a personal project for me. The cell that Fliteboard uses currently (the Molicel P42A) is a great battery, but it is getting quite outdated. The building technique that is used in the Flitecell, while incredibly safe and reliable, is not as lightweight as it could be for people like me who were chasing the latest and greatest and understand the limitations from a safety perspective. This is not a bad thing and is typical for most mass-produced products. Over the course of a year and a half, I discovered that the enclosure is one of the harder and more time consuming things about making eFoil batteries. Most people ended up using electrical junction boxes or not using waterproof enclosures at all. Helium is our answer to this.

It depends mostly on two things: which cells you choose, and whether you build the pack yourself or pay a battery builder to do it. Here is a rough breakdown for a 14S4P pack (56 cells), the most popular size:

• Helium Enclosure: $390
• Cells: about $2 to $15 each, so $112 to $840 for 56 cells
• Cell structure parts (cell holder grid and connections like copper or nickel strip): about $75
• BMS (Daly Active 150A): about $80
• Amphenol connectors: about $40
• Switch and pressure relief valve: about $15
• Silicone and dielectric grease: about $15
• Internal wiring, connectors and miscellaneous parts: about $65

Build it yourself: about $795 to $1,525 in parts, not counting tools.

Pay a battery builder: add their labor to the parts cost. Ask them for a quote. Our post Want a Built Battery if the Helium Kit Is Out of Stock? explains how it works and what to tell the builder.

Prices as of November 2026. Cell prices change often.

Built with the right cells, it can be longer lasting, lighter and more powerful.

If you are an aggressive rider, you will know that after about 60%, the power starts to sag under higher loads. With newer cells and proper construction techniques, an aftermarket battery can hold a higher power level for longer. In some testing I have done, instead of starting to lose power around 60%, it started losing power around 35%.

Redesigning and certifying an entirely new commercial battery is an incredibly expensive and time consuming process.

I expect Fliteboard to need a new battery in the near future. The cell they currently use, the Molicel P42A, is now about five generations old. Supply is becoming an issue and the cost is going up, because factories would rather make current generation cells than an outdated one. Many other battery makers have run into this, and Fliteboard’s battery manufacturer is likely no exception.

Riders who like building things and want the highest level of performance. These are DIY projects for people who understand lithium-ion batteries and how they work.

If you want something that is plug and play, buy a Flitecell from Fliteboard instead. That is the right choice for most riders.

Yes. eFoil batteries store a lot of energy, and a mistake can damage equipment, start a fire or cause injury. Only take this on if you are confident working with lithium-ion batteries, or have a qualified technician do the work. You are responsible for safe assembly, charging, storage and use. See our Battery Safety page for the basics.

Fliteboard Series 2 and newer. The Helium Enclosure has the same physical dimensions as the Flitecell Sport battery from Fliteboard.

We like 21700 size cells for their power to weight ratio. Our first choice is the Tenpower 60XG. We also like the Great Power 60Q and the Reliance RS60. For colder climates, we like the Reliance RS50. If cost is no issue, the Linkdata 70P is also a good choice, though its cycle life is not as good as the other cells we recommend. We recommend staying away from the EVE 50PL.

18650 cells also fit, but in our experience 21700 cells are usually the better choice for performance.

These are our recommendations from experience. Always buy cells from a reputable supplier.

The Flitebox can pull up to 120 amps before a cutout occurs. Your cells and BMS need to be able to handle at least 120 amps.

We like the Daly Active 150A BMS because of its form factor and features. You can buy it from the DALYBMS Official Store on AliExpress (opens in a new tab). Choose the 150A, 7S-17S option. The page may open on a different option, so select it before you add it to your cart.

We don’t sell third-party parts and can’t guarantee them. Check that every part suits your build.

The stock Flitecell uses a magnet inside the lid that triggers a reed switch inside the battery. For simplicity’s sake, I chose to stay away from that design. Helium uses the key function on the Daly BMS instead, with a latching push button or toggle switch (not a momentary button) on the front of the battery. We recommend this waterproof metal push button switch (opens in a new tab). Choose NO LED, Self-locking (1NO) and 12mm (1NO). Self-reset is momentary and will not work. Another option is this 12mm mini push button switch (PBS-33B) (opens in a new tab). Choose a color marked Self Locking, such as Black Locking.

The internal dimensions are listed in the Helium Enclosure product description.

Yes. Read How to Assemble the Helium Enclosure. Other documents are on our Documents page.

In the current Fliteboard firmware there is no known block or restriction on using a third-party battery. Firmware is controlled by Fliteboard, and a future update could change this.

When a new firmware update comes out, do not install it right away. Wait until we confirm here that the update does not block third-party batteries.

Not perfectly while you are riding. The board estimates the percentage from a mix of battery voltage and current, so with an aftermarket battery the reading can drift while you ride.

For an accurate reading, stop for a few seconds and let the battery rest. The percentage will update to the correct number.

The low voltage ramp down (where the gear levels slowly decrease at the end of the charge) still works like normal, as this is a purely voltage driven value.

Yes. We are developing The Bridge, a device that makes an aftermarket battery look exactly like a stock battery to the Flitebox, so the percentage reads accurately at all times. I have a working prototype and am looking for beta testers who currently use a Daly BMS in an aftermarket battery. If that is you, email charlie@posterduckcustoms.com.

A breakout system for the electronics in the board and a semi solid state battery. Check back here for updates.

We support right to repair and riders working on their own gear. How Fliteboard treats modified boards and batteries under its warranty is up to Fliteboard, so check their terms before you start.

Damage that happens while you are working on your board or battery is your responsibility, not Posterduck Customs’.

Custom items are made to order and usually take about 2 weeks to build before they ship. Ready-made parts usually ship sooner. You will get an email with tracking as soon as your order ships.

All sales are final because our products are made to order. Please ask us any questions before you buy. Every order is covered by our limited warranty.

We repair or replace items that arrive damaged, defective or not what you ordered, and items that fail from a defect in our materials or workmanship during normal use. Coverage is 90 days from delivery for most products and 30 days for electronic components.

It does not cover normal wear, crashes or impacts, misuse, incorrect installation, or water damage from improper sealing or care. See our Returns, Refunds and Warranty page for full details.

Email charlie@posterduckcustoms.com within the warranty period with your order number, a description of the problem and photos or a short video. If we need the item back, you pay to ship it to us, unless your order arrived damaged or we sent the wrong item, in which case we cover shipping.

Anywhere in the United States. If you are outside the US, email charlie@posterduckcustoms.com and we will see what we can do.

Shipping is based on the total weight of your order and is shown at checkout before you pay. We ship USPS or UPS from Lakeville, Minnesota.

Email us within 7 days of delivery with your order number and photos of the item and packaging. We will make it right and cover any shipping needed to do so.

Credit and debit cards, Apple Pay, Google Pay, or a direct payment from your US bank account.