Small-scale electrification has ceased to be the domain of experimenters and has become the standard for those who enjoy quiet fishing and relaxing on the water. tractor-batteryUnlike starter models, which give off power with a short, powerful pulse, boat batteries must provide a stable discharge for many hours.
Choosing the right energy storage device is not just a plug box, it’s a complex engineering challenge. The wrong container or type of chemistry can lead to you getting stuck in the middle of a pond or losing a significant amount of money on frequent equipment replacement. In this article, we’ll look at all the nuances of selecting, operating and maintaining power supplies for your home. electric motors.
The current market offers many solutions, but not all of them are suitable for use in high humidity and vibration. Understanding the principles of operation of different types of batteries will allow you to avoid common mistakes when equipping your boat.
Differences between traction batteries and starter batteries
Many beginners make the mistake of putting a conventional car battery on an electric motor, thinking that the main thing is voltage. This misconception can cost you batteries in one season. Starter batteries (SLI — Starting, Lighting, Ignition) are designed to give a huge current in seconds to start the internal combustion engine, and then instantly restore the charge from the generator. Their internal structure of the plates is thin and porous, which allows you to reach a large area of contact with the electrolyte, but makes them vulnerable to deep discharge.
Traction batteries Deep Cycles are a very different design, and the lead plates are thicker, often in tubes or lattices with alloying elements like calcium or antimony, which allows them to withstand hundreds of discharge cycles of up to 80 percent and subsequent charge without significant loss of capacity, and if a deep discharge starter battery can lose up to 20 percent of its capacity after the first cycle, then the traction battery is designed to do just that.
Using the starter battery in traction mode will lead to rapid showering of the active mass of the plates and the device failure. Moreover, the real energy output of the starter battery in long-term discharge of low currents will be significantly lower than the declared capacity of the C20. For a boat with an electric motor, it is critical to use specialized solutions such as: GEL, AGM Or lithium assemblies.
⚠️ Attention: Never discharge a typical car battery below 70% of its rated capacity, causing irreversible chemical sulfation processes in the plates, and it will be almost impossible to restore it.
When you choose, look for the labels. Manufacturers often specify the type of destination right on the case. Deep Cycle Also important is the number of cycles that the manufacturer guarantees at a certain depth of discharge (DOD). For lead-acid batteries, 300-500 cycles at 50% discharge are considered normal, while lithium analogues withstand more than 2000 cycles.
Types of batteries for electric motors
There are several major technologies in the world today, each with its own advantages and disadvantages, and understanding the differences between them will help you choose the best option for your budget and style of riding, with lead-acid technology with absorbed electrolyte and the latest lithium-iron-phosphate solutions remaining the main players in the market.
Technology AGM (Absorbent Glass Mat) means that the electrolyte is bound, soaking fiberglass mats between the plates, and they're completely sealed, maintenance-free, and can operate in any position other than inverted, and they have low internal resistance, which allows them to give off high currents, but deep discharge is not desirable, although it's better tolerated than liquid counterparts.
Gel batteries (GELThey are even more resistant to deep discharges and vibrations than AGM, but require very precise charging parameters. Exceeding the charge voltage by even 0.1 Volts can lead to gas formation and swelling of the body, after which the battery becomes unusable, but the service life of quality gel models can be up to 10-12 years.
Lithium-iron-phosphate batteries (LiFePO4They are much lighter than lead analogues (by 3-4 times), have no memory effect and can discharge to almost zero without harm to chemistry. BMS Battery Management System is a protection board that controls the balancing of cells, temperature and currents, and despite the high initial cost, their resource pays off in several seasons of active operation.
- 🔋 AGM: The optimal ratio of price and quality, are not afraid of shaking, charged with conventional chargers.
- 💧 GEL: Maximum deep discharge resistance, but require special chargers with precise voltage settings.
- ⚡ LiFePO4: Minimum weight, maximum energy efficiency (100% capacity vs 50% lead), long service life.
- 🚫 Liquid (WET): Cheap, but require maintenance, emit gases when charging and do not tolerate the inclinations of the boat hull.
Calculation of capacity and time of autonomous operation
The correct calculation of capacity is the key to not having to row with oars. The basic unit of measurement is the Ampere watch (Ah). However, just looking at the number on the label is not enough. You need to take into account the voltage of the system (12, 24 or 36 Volts) and the current consumed by the motor. The consumption of the electric motor is nonlinear: at low speeds it can be 5-10 Amps, and at maximum speeds it can reach 40-50 Amps or more.
The golden rule is that you can't use more than 50 percent of your rated capacity for lead-acid batteries. So if you have a 100-Ah battery, you only have 50-Ah. If the motor consumes an average of 25 Amps, it only lasts 2 hours. For lithium batteries, it's 80-90%, which makes them almost twice as efficient at the same value.
Consider an example of a 36 lb PVC boat that uses an average cruising speed of around 15-20 Amps at 12 Volts. If you plan to fish for 6 hours, you need a power reserve of 20 A * 6 h = 120 Ah. For a lead battery, that means buying a 240 Ah model, which is very high and heavy. A 120-140 Ah lithium battery will cover that need.
Always round the design capacity upwards by 20-30%, with cold water, wind and current increasing the boat's resistance to movement, which causes the motor to consume more power.
And it's also important to consider the Peckert effect, which says that when you run high discharge currents, the effective capacity of the lead battery decreases. If you walk at high speeds often, the actual operating time will be less than the estimated. Lithium batteries are almost immune to this effect.
| Motor type (thrust) | Medium current (A) | Capacity of AKB (Ach) | Working hours (AGM) | Working hours (LiFePO4) |
|---|---|---|---|---|
| 30-35 lb | 12-15 A | 100 AH | 3.3 - 4 hours | 6 - 7 hours |
| 45-50 lb | 20-25 A | 100 AH | 2 hours | 3.5 - 4 hours |
| 55-60 lb | 30-35 AA | 100 AH | 1.4 hours | 2.5 hours |
| 80+ lb (24B) | 20-25 A | 100 AH | 2 hours | 3.5 - 4 hours |
Connection schemes and chargers
Charging quality directly affects battery life. Use of an inappropriate charger (ROM) is the most common cause of premature death of expensive batteries. Lead batteries require a three-stage charge cycle: primary charge, absorption and floating mode. For gel and AGM batteries, the absorption voltage should not exceed 14.4-14.7 Volts, otherwise irreversible gas formation will begin.
Lithium batteries require chargers with profile LiFePO4Charging with a lead charger may not “open” the battery completely or, in the worst case, trigger the BMS protection, after which some cheap models can lock and require a complicated unlocking procedure. Modern “smart” chargers often have a mode switch or automatically determine the type of battery connected.
When building a system with multiple batteries (for example, for a 24 or 36 Volt motor), it is critical to use batteries of the same model, one year of release and preferably from the same batch. Sequential connection (increased voltage) requires a perfect balance of capacity. If one battery in a bunch is weaker, it will discharge faster and go into deep discharge, which will disable the entire chain.
☑️ Checking before getting on the water
Use only copper cables to connect with the load current section. For currents up to 50 Amps, a cross section of at least 16 mm2 (6 AWG is recommended, and for high-power motors 25 mm2 (4 AWG) and thicker. Long thin wires lead to voltage drops and heating, which reduces the efficiency of the motor.
⚠️ Attention: When connecting batteries in series, never connect the charger to only one battery in the chain, either charge the entire assembly with a special high-voltage RAM, or disconnect the batteries and charge each separately.
Rules of operation and storage in winter
Lead acid batteries are extremely sensitive to temperature. In the cold, the electrolyte can freeze, especially if the battery is discharged. In the charged state, the freezing point of the electrolyte is about -50 ° C, but in the discharged state (density 1.10 g / cm3), the water in the electrolyte turns into ice already at -7 ° C. As it expands, the ice destroys the plates and the body, making the battery unfit for repair.
Lithium batteries are also afraid of extreme temperatures, but for another reason. charger This results in lithium metallization on the anode and internal short circuit. Many modern models have built-in heating or charge protection in the cold, but it is better to store them in heat. The optimal storage temperature for all types of batteries is from +10 °C to +20 °C.
Before winter storage, the lead battery must be fully charged, a training cycle is recommended every 1-2 months, or simply recharge the battery to compensate for self-discharge. Lithium batteries can be stored at a charge of 50-70%, they have extremely low self-discharge current and can lie for several months without additional attention.
Can I store the battery on the concrete floor?
Modern plastic enclosures (PP, ABS) are well insulated, and the old myth that the battery sits through concrete is related to wooden cases and glass jars from the last century, but it is not recommended to put batteries directly on the cold floor because of the temperature difference, it is better to use a wooden stand or a shelf.
When you canned a boat for the winter, be sure to disconnect the terminals. Even the electric motor or installed additional appliances (navigator, sonar) can consume current in standby mode, slowly killing the battery over several months of downtime.
Common mistakes in selection and service
One of the most common mistakes is to save on wires and terminals. When buying an expensive lithium battery, users often leave old, oxidized wires as a nail cross section, which negates all the benefits of a new battery by causing voltage drawdowns and heating contacts. Always use tinted copper tips and tightly clamp them.
Another mistake is sealing. In a boat, especially an inflatable one, the risk of water getting into the boat is high. Battery terminals are susceptible to corrosion due to salt air and spray. It is recommended to treat contacts with a special lubricant for terminals or use protective caps. It is also worth checking the reliability of the battery itself: vibration on the wave can wipe even a thick cable on the edge of a runduk.
Remember, for lithium batteries, it is critical to keep the BMS from going to zero when stored. If the BMS goes into deep protection, some models will require a voltage connection to push, and cheap Chinese builds may simply lock up forever.You should also avoid mixing batteries from different manufacturers or with different residual resources in the same system. Even if the voltages on the voltmeter coincide, their internal resistance may differ, which will lead to uneven operation and accelerated wear of the entire system.
The battery life is 80% dependent on the correct charging and storage conditions, not just the manufacturer’s brand.
FAQ: Frequently asked questions
Can a traction battery be charged with a conventional car charger?
Only if it's a modern automatic RAM with a mode for AGM/GEL and the ability to select voltages. Old transformer charges boil the electrolyte, which is harmful for sealed batteries. LiFePO4 needs a special RAM with a lithium profile.
Which battery is better for a PVC boat: AGM or Lithium?
If the budget is limited, take a high-quality AGM. If weight (for carrying in a backpack) and long service life are important, LiFePO4 is definitely important. Lithium pays off in 3-4 seasons of active fishing.
Why is the electric motor weaker at the end of the fishing trip?
The battery is likely to come to the discharge threshold. In lead batteries, the voltage drops gradually, and the motor loses power. In lithium, the voltage is stable until the very end, and then the protection is abruptly turned off.
Do I need to maintain traction batteries?
Airtight AGM, GEL and Lithium are maintenance-free. Liquid (WET) require regular checks of electrolyte levels and density, as well as a dose of distilled water.
Is it dangerous to carry a lithium battery in a boat?
LiFePO4 is considered one of the safest and most stable chemicals, and it doesn't burn or explode even when you're mechanically damaged, unlike lithium cobalt batteries in phones, but it's still important to protect yourself from water coming in and plugs closing.