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AGM battery for my boat

Aquamot, Victron Energy and Co

Popular AGM batteries for the boat

"What AGM batteries are available for my boat?" - You can easily find the right battery type and model for your boat in the categories. Here you will find almost all manufacturers and models available on the market for maritime applications.

You are not sure which AGM battery is the most suitable? Give us a call! We have a selection of over 20 different AGM batteries from several manufacturers.

Special features of AGM batteries - What do I have to pay attention to?

AGM batteries are available in different sizes and capacities. You will find all variants from 0,5 kWh up to 3 kWh capacity in our shop. The batteries can usually be connected in parallel and series. Upwards there are no limits. Depending on your requirements, you will need about 0.5 kWh of power per tonne per hour in displacement mode and exponentially more in gliding mode. For gliding travel we recommend AGM batteries due to the weight, but not AGM batteries.

The batteries are connected directly to the motor via cable. The closer the batteries are to the engine, the less loss is caused by cable lengths. If you have any questions about cable thickness, we will be happy to help!

The batteries can be connected to the engine much more conveniently and user-friendly using plugs or battery clamps. Of course, you can also purchase the batteries without additional cables and connectors and just connect the cables.

Especially with 12 Volt and 24 Volt rear engines Deep AGM batteries are super suitable and also the capacity is sufficient for small trips or fishing trips. Depending on use we recommend the right size.

victron batteries

Weight of the AGM cells

AGM batteries are a further development of the classic lead-acid batteries in which the acid is bound in a glass fleece. This leads to the fact that the batteries are leak-proof and offer my higher performance. The lead leads to a high weight of the batteries of about 30 kg per kilowatt-hour.

With many sailboats, the additional weight is in any case secondary or serves as a weight in the hull. AGM-batteries are also often well suited for large displacers. For semi-gliders and gliders, however, the weight per kWh is often important and therefore we usually recommend lithium batteries.

Regardless of the battery technology, you should make sure that the weight per package is comfortable to carry.

Ladezyklen einer AGM Batterie

The charging cycles can be very different. The charging cycles are usually indicated by a degree of discharge. (DoD = depth of discharge) The deeper the batteries are discharged, the shorter the charging cycles. At 50% DoD, high-quality AGM batteries last 750 cycles, but conventional AGMs last significantly less. They should not be discharged deeper, as irreversible damage can occur. For most batteries, this results in service life of 5 to 10 years, depending on use.

However, there are also higher quality battery packs available. These cells can be partially discharged to 80% (deep cycle) or 100% (supercycle) and do not suffer any damage. The price differences are not too high, so we recommend at least the deep-cycle technology as used by Aquamot or Victron Energy. The Super-Cycle technology is still very new and so far mainly found at Victron Energy.

Prices, brands and cell technology

The prices depend on various factors. A price per kWh of 220 € to 300 € is reasonable. In individual cases, prices above 300 € per kWh are also possible for the special Super Cycle batteries. Often you can already find suitable AGM batteries in car workshops for less money. We usually recommend batteries from Victron Energy in combination with the chargers. Suitable for the Aquamot E-drive of course the complete system from Aquamot.

Most AGM battery emulators are manufactured based on AGM (Absorbent Glass Mat). This is a design form of lead acid batteries and is often known as VRLA technology. Depending on the type of battery, different connections and components are possible. In general, the batteries are very leak-proof and not susceptible to faults.

AGM battery

AGM batteries for boat engines - Which manufacturers are there?

AGM batteries are not only widely used in boats, but also in cars and caravans and have often completely replaced the classic lead-acid battery. From the automotive sector, many people know the batteries from Varta.

These batteries are also used in the boat sector. We rely on AGM batteries from Aquamot, which are technically equivalent to the well-known batteries from Zenith. As a good alternative we also offer the Deep Cycle and Super Cycle AGM batteries from Victron Energy.

Use of AGM batteries

We always recommend a complete package from one manufacturer to save additional costs and ensure functionality. Some electric motors, however, do not have their batteries, since virtually all batteries can be combined with the motor.

If you use your boat as a rental company or in the industry for commercial purposes, we recommend specially designed batteries from the premium segment. Aentron offers a special certification and is one of the only suppliers here. Often these are installed in combination with herbal products in ships.

The same applies to higher travel times (50+) per year. The lithium cells from Otherwise, Victron Energy is also a manufacturer with very high-quality components. In this case, it is recommended to use the matching battery in addition to the chargers of the market leaders.

Advantages and disadvantages of AGM over lithium

A big advantage is a price per kWh, which at first glance appears to be lower. The acquisition costs are currently still one of the most important issues for the e-propulsion system, as lithium technology is often twice as expensive. Apart from the price, there are no major advantages.

Depending on the technology, the depth of discharge is lower, and therefore less capacity per kg battery can be used effectively. AGM batteries can usually be discharged to 50%. Depending on the technology, AGM batteries are damaged at 50% discharge and should not be deeply discharged. They tend to be more suitable for shorter trips. You should always pay attention to this during use.

Furthermore, an AGM battery weighs three times as much as a lithium-ion battery. Furthermore, AGM batteries usually have only 750 charging cycles and lithium batteries up to 5000 cycles. Therefore, the price difference is relativized quite quickly. If I have to buy two battery packs in the same usage period, an AGM battery is probably not worth it.

An AGM battery can also not be loaded so heavily. Currents should only be one-fifth of the capacity (0.2 C) in order to achieve a halfway good lifetime and driving time. The faster an AGM battery, the less energy (Ah) the battery supplies. The battery is usually specified as C20, i.e. for a discharge over 20 hours. If the battery is discharged in 5 hours, you will then only have about 80% of the specified Ah and if it is discharged in two hours, you will have less than 70%!

The bottom line is that lithium batteries have clear advantages. Our recommendation is long-life lithium batteries, but AGM batteries might be useful or better for occasional use. Talk to us - together we will look at your conditions and find the perfect overall system!

victron energy agm battery

Monitoring and control of the lead-acid battery

A lithium battery is monitored by a battery management system. The BMS provides protection mechanisms and outputs important characteristic values. This is not the case with an AGM battery. As a rule, the key figures can only be read out via a separate display. Fortunately, the battery hardly needs any other protective mechanisms and offers fewer sources of error.

Installation of an AGM battery

Depending on how fit you are in handling batteries, we recommend ready-made solutions or at least individual components. Ready-made systems are usually easy to connect via Plug & Play. However, you can save a few euros if you do the cabling yourself or do not use a protective plug but connect the poles directly to the cable.

Charging is easily possible via a charger and access to shore power with up to 3 kW charging capacity. Marinas, therefore, offer the possibility to charge the supply and drive batteries according to use.

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