Foil Drive • Gen2.5 • FD401
Foil Drive FM+ 650 Battery
648Wh of battery capacity for Assist MAX+ and Fusion.
The FM+ 650 is a 43.2V battery built for Foil Drive's Gen2.5 systems. It fits the Assist MAX+ directly. For the longer Fusion unit, pair it with the separately available FM+ Battery Adaptor. That gives Fusion riders a lighter battery option than the Fusion 860 and lets riders with both systems share one FM+ 650 battery.
The sealed, one-piece battery includes an integrated nose cone and an intelligent battery management system that reports charge information to the V3 Controller and Foil Drive App. This battery is not compatible with the Gen2 Assist MAX.
- 648Wh • 15Ah
- 43.2V Gen2.5
- 3.95 kg / 8.7 lb
- Direct Fit for MAX+
- Fusion: Adaptor Required
Why Choose the FM+ 650?
One Battery, Two Systems
Use the FM+ 650 in Assist MAX+ as supplied, or add the FD330 FM+ Battery Adaptor to fit it into a Fusion unit.
648Wh Capacity
Designed for longer surf sessions, assisted upwind access, wake riding and flatwater starts, with 15Ah of rated capacity.
Battery Data at a Glance
The built-in battery management system shares charge level, status and health information with the V3 Controller and Foil Drive App.
Integrated Nose Cone
The molded battery and nose cone form a single unit for a clean fit and water flow around the installed battery.
What’s Included — and What You Still Need
- One Foil Drive FM+ 650 Battery (FD401)
- FM+ 650 Battery Carry Case
Battery only. The Foil Drive system, 43V charger, Fusion FM+ Battery Adaptor and Battery Caddy are not included. You need a compatible 43V Foil Drive charger to recharge the battery.
Using Fusion? The FM+ 650 needs the FM+ Battery Adaptor to fit the longer Fusion unit. Check whether your Fusion kit already includes the adaptor before ordering one separately. The battery also works with the Foil Drive Battery Caddy when paired with the FM+ adaptor.
Key Specifications
| Specification | FM+ 650 Battery |
|---|---|
| Rated capacity | 648Wh / 15Ah |
| Nominal voltage | 43.2V (50.4V maximum) |
| Battery weight | 3.95 kg / 8.70 lb |
| Battery dimensions | 460 × 125 × 55 mm |
| Length installed in MAX+ | 540 mm (overall installed dimensions: 540 × 125 × 55 mm) |
| Length installed in Fusion | 658 mm with FM+ adaptor (overall installed dimensions: 658 × 125 × 55 mm) |
| Typical charge time | About 85 minutes with a compatible 43V charger; actual time varies |
| Foil Drive SKU / GTIN | FD401 / 9361123003493 |
Capacity versus name: “650” is the battery model name. Foil Drive lists its rated capacity as 648Wh.
Foil Drive’s Indicative Runtime
These figures come from Foil Drive’s FD401 test scenarios. They describe a complete setup and riding conditions, not a guaranteed session length for every rider.
| Activity | Intermediate rider | Advanced rider |
|---|---|---|
| E-foiling | About 31 minutes | About 52 minutes |
| Surf foiling | About 40–50 minutes | About 55–70 minutes |
Test conditions: Foil Drive used an 80 kg rider, 800 cm² wing and 5'0" / 40 L board. The e-foil estimate used flat water at about 70% throttle. The surf estimate used 3 ft swell and wind below 5 knots. Results change with rider weight, skill, foil and board size, motor use and conditions.
Compatibility and Battery Care
- Assist MAX+: The FM+ 650 fits directly; no battery adaptor is needed.
- Foil Drive Fusion: Requires the FM+ Battery Adaptor (FD330) to fit the shorter battery in the longer unit.
- Foil Drive Battery Caddy: Use the FM+ Battery Adaptor when fitting the FM+ 650 to the caddy.
- Charging: Use a compatible Foil Drive 43V charger. The charger is sold separately from this replacement battery.
- Gen2 Assist MAX: Not compatible. A battery adaptor does not make this Gen2.5 battery work with a Gen2 MAX unit.
- Storage: Follow the battery and charger manuals; Foil Drive recommends storing the battery at 30–60% state of charge.
Frequently Asked Questions
Is the FM+ 650 compatible with my Assist MAX+?
Yes. The FM+ 650 fits Assist MAX+ directly. It is not compatible with the older Gen2 Assist MAX.
Can I use it in Foil Drive Fusion?
Yes, with the FM+ Battery Adaptor (FD330). Check your Fusion kit first; you may already have the adaptor.
Does the battery come with a charger or adaptor?
No. Foil Drive lists the FM+ 650 Battery and its carry case in the package. The 43V charger and Fusion adaptor are separate.
Why does the battery say 650 if it is rated at 648Wh?
FM+ 650 is the model name. Its manufacturer-listed capacity is 648Wh.
How long will it run?
Foil Drive’s indicative figures range from about 31–52 minutes for e-foiling and 40–70 minutes for surf foiling in its stated test setups. Your riding time will vary with conditions and how much you use the motor.
Need Help Checking Your Setup?
Tell us whether you ride a MAX+ or Fusion and which charger and battery adaptor you already have. We can help check the parts before you order. Email Windance or call 1-800-574-4020.