The essentials in 30 seconds
- The voltage is dictated by the motor. Garmin Force Current: 12 or 24 V; Force Pro, Force Kraken and Lowrance Ghost X: 24 or 36 V.
- Check the continuous current the battery can supply: 60 A for a Force Pro or a Kraken, 40 A for a Force Current. Rebelcell EDGE models are rated for 100 A.
- Range is calculated: capacity in Ah divided by the motor current at the speed used, read from the Garmin chart. An order of magnitude, not a measurement.
- One charger per chemistry: 14.6 V for a LiFePO4 12 V, 29.2 V for a 24 V, 12.6 V for Li-ion AV.
- Above 100 Wh, a lithium battery travels as dangerous goods: transport on quotation, confirmed after order. No Skysat installation is documented; all data comes from datasheets.
Table of contents
- First, the voltage: the motor decides
- Single battery or multiple in series?
- Continuous current, the overlooked spec
- Capacity and range: the method and its limits
- Chemistry and charger: one profile per battery
- Protection, cables, and battery switch
- Transport and winter storage
- Limits and pitfalls
- Our verdict by motor
First, the voltage: the motor decides
Selecting an electric motor battery follows this order: voltage, current, capacity, charger. Voltage is non-negotiable; it is specified in the motor’s manual.
| Motor | Accepted voltage | Published input range | Continuous current | Required protection |
|---|---|---|---|---|
| Garmin Force Current | 12 or 24 V | 10 to 32 V DC | 40 A | 40 A fuse or circuit breaker |
| Garmin Force Pro and Force Kraken | 24 or 36 V | 20 to 45 V DC | 60 A | 60 A circuit breaker, rated for 42 V DC or higher |
| Lowrance Ghost X | 24 or 36 V | not published | not published | 50 A circuit breaker (series Ghost manual, 2020) |
Garmin manuals and series Ghost installation manual, listed at the end of the article.
A LiFePO4 “12 V” battery operates at 12.8 V nominal and charges at 14.6 V. A “24 V” battery operates at 25.6 V and charges at 29.2 V. The Rebelcell 36V70, Li-ion, shows 37 V nominal and 42 V when charging. These values fall within Garmin’s published ranges. This is a numerical comparison, not a manufacturer’s homologation of the motor.
Never use a starter battery. Rebelcell states in the EDGE manuals: do not use them to start a combustion engine. Conversely, Lowrance recommends deep-cycle marine batteries for its Ghost series.
Single battery or multiple batteries in series?
With lead-acid batteries, Minn Kota’s published rule is simple: one 12 V battery per 12 V segment. Two in series for 24 V, three for 36 V.
With lithium, only the battery’s datasheet applies. Rebelcell allows two EDGE 12 V batteries in series (24 V) and four in parallel for its EDGE models. For the 24V75 EDGE, two in series give 48 V, not 36 V.
Three EDGE 12 V batteries in series to make 36 V? No. A 36 V motor requires a native 36 V battery, such as the Rebelcell 36V70, or a setup explicitly approved in writing by the manufacturer.
Direct current, the overlooked characteristic
A lithium battery contains a BMS, the electronics that protect it. Rebelcell states for its EDGE models: above 100 A continuous, the battery shuts down, and so does the motor.
The continuous current rating of the battery must exceed that of the motor. Force Pro or Kraken motors require 60 A; Force Current requires 40 A. The Rebelcell 12V18 AV and Rebelcell 12V30 AV, limited to 20 A, are sounder batteries.
| Battery | Chemistry | Nominal voltage | Capacity | Energy | Continuous discharge | Weight |
|---|---|---|---|---|---|---|
| Rebelcell 12V75 EDGE | LiFePO4 | 12.8 V | 75 Ah | 960 Wh | 100 A (200 A for less than 5 s) | 6.9 kg |
| Rebelcell 12V105 EDGE | LiFePO4 | 12.8 V | 105 Ah | 1.34 kWh | 100 A | 9 kg |
| Rebelcell 12V210 EDGE | LiFePO4 | 12.8 V | 210 Ah | 2.69 kWh | 200 A (400 A for less than 5 s) | 18.2 kg |
| ROYPOW 24 V 50 Ah | LiFePO4 | 25.6 V | 50 Ah | 1.28 kWh | 80 A (120 A for 10 s) | 14 kg |
| Rebelcell 24V75 EDGE | LiFePO4 | 25.6 V | 75 Ah | 1.92 kWh | 100 A (200 A for less than 5 s) | 13.5 kg |
| Rebelcell 36V70 (not in Skysat catalogue) | Li-ion | 37 V | 70 Ah | 2.69 kWh | 100 A (120 A for 10 s) | 15 kg |
Notices and pages from Rebelcell, ROYPOW brochure, and Skysat datasheets, consulted on September 30, 2026. None of these values are Skysat measurements.
Capacity and range: method and limitations
Rebelcell provides the formula in its knowledge base: required capacity in Ah = motor current in A × desired hours. The current comes from the motor manufacturer’s chart, not its maximum power.
Garmin publishes this chart for the Kraken and the Pro. At 25.6 V, the motor draws 3.1 A at speed 5, 10.8 A at speed 10, and 27.3 A at speed 15. At full speed (20): 58.9 A. At 38.4 V: 1.9 A, 7.5 A, 19.7 A, and 55.9 A. The Force Current draws 32.8 A at 25.6 V and 33.9 A at 12.8 V at full speed.
| Battery and motor | Speed 10 | Speed 15 | Speed 20 |
|---|---|---|---|
| Rebelcell 24V75 EDGE (75 Ah) with Force Pro or Kraken at 24 V | 6.9 h | 2.7 h | 1.3 h |
| ROYPOW 24 V 50 Ah with Force Pro or Kraken at 24 V | 4.6 h | 1.8 h | 0.8 h |
| Rebelcell 12V75 EDGE (75 Ah) with Force Current at 12 V | not published | not published | 2.2 h |
| Rebelcell 36V70 (70 Ah) with Force Pro or Kraken at 36 V | 9.3 h | 3.6 h | 1.3 h |
Skysat calculation: Ah ÷ A, full battery, no reserve, using Garmin currents measured in calm water ±5 A. This is not a measurement on the water; Garmin does not publish range figures.
On the water, wind and current cause the GPS anchor to work intermittently: keep a reserve. Read the charge state in the Rebelcell app; the motor gauge is set for lead-acid by default.
Chemistry and charger: one profile per battery
The Rebelcell EDGE and ROYPOW are LiFePO4: charge at 14.6 V on 12 V, 29.2 V on 24 V. The Rebelcell AV and 36V70 are Li-ion: charge at 12.6 V and 42 V. Chargers are not interchangeable.
EDGE batteries charge between 0 and 45 °C and have no internal heating. The IP66 housing withstands water jets but not immersion: Rebelcell requires strapping the battery above the bilge water level.
| Battery | Charger | Published charge time | Maximum charge current |
|---|---|---|---|
| Rebelcell 12V75 EDGE | 14.6 V / 20 A or 14.6 V / 35 A | 4 to 5 h; 3 to 4 h | 35 A |
| Rebelcell 12V105 and 12V210 EDGE | the same | 6 to 7 h and 11 to 12 h (20 A); 4 to 5 h and 7 to 8 h (35 A) | 50 A; 100 A |
| Rebelcell 24V75 EDGE | 29.2 V / 20 A | 5 to 6 h | 35 A |
| Rebelcell 12V18 AV | 12.6 V / 6 A | not published | 6 A |
| ROYPOW 24 V 50 Ah | charger approved by ROYPOW; reference to be validated before commissioning | not published | not published |
Rebelcell EDGE 12 V manual, Rebelcell pages, Skysat datasheets. Charging from the dock is possible. Rebelcell accepts alternator charging via a DC-DC charger, and solar charging via a controller between panel and battery.
Protection, wiring and battery switch
- Garmin: 60 A continuous circuit breaker, rated for 42 V DC or higher, on the Force Pro and the Kraken. On the Force Current: 40 A. None supplied. The Blue Sea 285 series 60 A and the 285 40 A are rated for 48 V, IP67, spark-proof (SAE J1171).
- Wire gauge: Garmin mandates 16 mm² up to 3 m extension, 25 mm² up to 4.6 m, and 35 mm² up to 9.1 m. The Ghost manual calls for 8.5 to 13.5 mm².
- Rebelcell: a fuse between battery and equipment, M8 terminals tightened with a wrench, cables of sufficient cross-section, never use crocodile clips.
- Battery switch: a switch like the Blue Sea e-Series isolates the shore power bank and during winter lay-up, whereas Rebelcell requires everything to be disconnected.
Transport and winter lay-up
All batteries in this guide exceed 100 Wh: dangerous goods, class 9, UN3480, per Rebelcell. Our carriers only accept shipments of batteries up to 100 Wh in standard delivery. Delivery is therefore on quotation, with costs confirmed after order; pickup in Carnac depends on physical stock.
For winter, Rebelcell instructs to charge the EDGE to 70%, disconnect everything, and store it dry between 0 and 45 °C. Check the charge every three months in the app; recharge if below 50%, never below 0 °C.
Limits and pitfalls
- Calculations, not measurements. Neither Garmin nor Rebelcell publish any quantified autonomy figures for these engine-battery pairs.
- “Compatible with almost all 24 V motors” is a Rebelcell claim, not a Garmin certification. No plug-and-play harness exists.
- The BMS cuts power without warning beyond its limits, including in temperature conditions. Keep a paddle or the outboard motor as backup to return.
- Skysat has not yet installed any of these batteries on a fishing vessel. All information comes from the cited manuals.
Our verdict by engine
- Force Current 12 V (kayak, dinghy): the Rebelcell 12V75 EDGE, 100 A continuous for 40 A required. The 12V105 EDGE for longer days. 14.6 V charger.
- Force Current 24 V, or Force Pro and Kraken 24 V : the Rebelcell 24V75 EDGE, 100 A continuous. Charger 29.2 V / 20 A. The ROYPOW 24 V 50 Ah (80 A) suits short bursts.
- Force Pro, Kraken or Ghost X 36 V : a native 36 V battery. The Rebelcell 36V70 (70 Ah, 100 A) is available from the manufacturer, not yet at Skysat: contact us for a quotation.
- The depth sounder : a separate 12 V circuit, for example an 12V18 AV, as recommended in our guides. It is then independent of the propulsion BMS.
Sources
- Garmin: Force Kraken manual (v7, 11/2025), Force Kraken installation guide (v10, 01/2026), Force Pro manual (v3, 08/2026), Force Current manual (v3, 07/2026).
- Lowrance: page Ghost X 47"; installation manual for the Ghost series (988-12451-005, 2020) on the Skysat product page.
- Rebelcell: EDGE 12V75/105/210 manual (2025), pages for 24V75 EDGE and 36V70, knowledge base on trolling motor battery selection.
- ROYPOW: B2450A brochure (2025) on the Skysat product page. Blue Sea Systems: Skysat product pages for the 285 series circuit breakers. Minn Kota: Motor Selection Guide (2020).
Disclosure: Skysat sells Garmin, Lowrance, Rebelcell, ROYPOW, Blue Sea Systems and Minn Kota products. This article is neither sponsored nor reviewed by the brands mentioned.
