The German Energy Agency (dena) chose our off-grid India project for one of their best practice projects of innovative smart and sustainable energy technologies made in Germany. We are thankful and looking forward to more projects to come.

For more information about our project with live energy tracker click here



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Our LE300 Lithium Extension Battery can be used for many different applications tough it is mainly known for solar home systems and caravans. Today we want to show you the best practice of LE300 installed into a sailing catamaran.

The beautiful sailing catamaran WINDZANG with sail area of 50 m² and length of 9,30 m got an update for its worn-out energy supply system.

read more in our blog



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In January 19- 27. we are present at the Boat Düsseldorf.

We are very excited to introduce our LE300 Lithium Extension Battery together with SOLARA at hall 11 stand D24. From Monday till Wednesday, our team will be personally at the fair, meeting interesting business partners and customers.

The boat Düsseldorf is the biggest boat and water sports trade fair in the world and a perfect fit for our LE300 Lithium Extension Battery.

We are looking forward to meeting you at this great event.



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We will be at the CMT – The Holiday Exhibition in Stuttgart from 12 - 20 January 2019.
The Holiday Exhibition is the world largest exhibition for caravan, holiday homes and Travel.

Together with HYMER we present the perfect independent power solution for campers and caravans with the HYMER SMART Battery System and BOS LE300 Lithium Extension Battery.

We are looking forward to meeting you at Hall 1, Stand 1C12



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The biggest in our product portfolio, 10kWh capacity system, HS10000 was displayed at EES 2018 in Munich which was held together with Intersolar at The Smarter E. There our HS10000 was displayed at our partner Victron’s booth as well, which garnered a lot of attention.

In terms of PV system installation, it is very common to look at batteries, inverters and chargers as separate components, but HS10000 helps you view them as one product. The heart of the 48 V based HS10000 system is the Master Board, developed and engineered by BOS. It controls not only 10kWh of Lithium ion phosphate batteries but also the 5kVA Victron Multiplus inverter and 2 X 70 A Victron MPPT charge controller. The integrated solution helps to cut down the soft costs and reduces your installation time and hassles as everything is pre-wired and pre-configured.

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6th of September a group of around 20 people from Central America and the Dominican Republic visited our company. The whole event was organized by the Renewables Academy (RENAC) AG in cooperation with the German-Central America/Caribbean Chamber of Commerce (GTCC). Focusing on the topic “Decentralized Energy Supply with Renewable Energy with a focus on Storage Technology in Germany”, we were happy to present our business model and newest product developments.

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HYMER-Smart-Battery-System was awarded with one of the most prestigious award of the German leading automobile magazine AUTO BILD. In the category “best accessory novelty 2018” HYMER-Smart Battery-System won the editorial award of the Golden Auto Bild 2018.The award ceremony was held at the Caravan Salon 2018 in Dusseldorf (-02.09.2018). We congratulate and are thrilled about this special prize.

With the HYMER Smart Battery System you will experience more self-sufficiency, due to state-of-the-art lithium batteries which combines cost effective standard lead acid batteries. Our BOS Lithium Extension Battery LE300 is main component of the system.


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We are at the Caravan Salon 2018 in Düsseldorf, the world's largest trade fair for motorhomes and caravans.

Till 02.09.2018 you will find more self-sufficiency for your caravans thanks to the innovative HYMER Smart Battery System. The system consists of our LE300 Lithium Extension Battery modules and will be connected to the existing lead acid battery. Come and visit the HYMER booth in hall 17, we are looking forward to meeting you.

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We are excited to present you our fully certified LE300 Lithium Extension Battery. It has the CE marking and with its E24 certificate it is even entitled for automobiles.

With our Lithium Extension Battery you can add capacity and improve the efficiency of any 12 V lead acid battery in an easy and cost-effective way. The intelligent technology allows multiple LE modules to be stacked in parallel to meet your specific system specs. No more worries about too low capacity, energy losses and short product lifetimes.

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Improve the performance of your lead acid battery by combining it with innovative lithium batteries (LiFePO4)


BOS Lithium Extension Battery is a fully scalable solution to enhance performance and add capacity to lead acid batteries in solar and any other kind of energy storage systems. They can be used with new or existing 12 V lead acid batteries. Just stack them in parallel to meet your specific system specs.

Product Description Application Product Features Technical Specs


LE300 6er klein





Our Lithium Extension Battery is a fully scalable solution to enhance performance and add capacity to lead acid batteries in solar and any other kind of energy storage systems. It comes in a robust housing and can be used with new or existing 12 V lead acid batteries. The intelligent technology allows multiple LE modules to be stacked in parallel to meet your specific system specs.

Like in all BOS AG Hybrid battery systems, the lithium battery takes most of the charging cycles while the lead acid battery provides inexpensive backup capacity. The lead acid battery is charged with higher priority, while the lithium battery takes all surplus energy. This process helps to increase the lead acid battery lifetime.

The integrated battery management system recognizes the lead acid battery voltage and automatically starts to support the lead acid battery. Lithium battery powers most of the loads, while lead acid is kept at floating point most of the time. However, bigger loads are supported by lead acid and the lithium battery simultaneously, which results smaller currents for each battery, reducing the strain on both the batteries.


 LE zertifizierung


ees AWARD2016 Logo finalist EN Pfade



Example areas where you can use our Lithium Extension Batteries


LeadAcid Backup

BOS Icon Caravan

BOS Icon Sailing

BOS Icon Telecommunication Tower

BOS Icon Solar Home Systems

Lead Acid Back-Up
Telecommunication Tower
Solar Home Systems




Lithium for cycling. Lead acid for basic load.

In pure lead acid systems, batteries often fail within one to three years, as batteries get damaged by continuous operation at low state of charge. Pure lithium systems perform way better and show longer lifetimes but are very expensive. Initial investment costs for hybrid systems are close to the costs of pure lead acid systems and approx. 50% lower than pure lithium systems. As costs per stored kWh are around 60% lower in hybrid systems than in lead acid systems, the hybrid system becomes the most cost effective option already in the first three years.


Longer battery lifetime

The lead acid battery is not strained by deep charging cycles, as the lithium battery is used for running daily cycles. During its long hours at full state of charge the lead acid battery is floated. Compared to pure lead acid systems both effects positively impact the lead acid battery lifetime. By preventing harmful sulphation, the lifetime can be increased to more than 10 years. This lowers the operating cost of energy storage significantly and has a positive impact on the environment. The lithium battery offers enough charging cycles for more than 10 years of daily use. The lithium battery furthermore recharges the lead acid battery in case that it didn't get fully charged during the day, a case which frequently happens in solar applications.





LE300 E24 Certification


Robust housing for automobile

An elegant design and robust housing keeps the state of the art lithium batteries safe. Thanks to an optimised sizing and variable fixing possibilities the modules fits even in small corners. Each module is E24 certified which allowes them to be installed in automobiles as well.


Easy to scale up

LE modules can be easily staged together to meet your individually specific system specs. Up to 24 (7.8kWh Lithium capacity) LEs can be stacked together.


LE300 6er

LE300 Charging  

Retrofitt or extend your present lead acid battery

BOS Lithium Extension Batteries can be connected to any new or existing 12 V lead acid battery. No additional charge controller or additional changes are needed.


Low temperature resistance

All LE modules have an integrated heater, so the lithium batteries are protected against cold temperatures and perform without any energy losses.

  Cold hot LE300

PlugandPlay LE300


Plug and play

With the plug and play system, LEs are easy to install. They simply need to be connected with plus (+) and minus (-) poles straight to the lead acid battery.


Increased system performance

Immediately after installing the LE, the complete system performance improves. The Smart Battery management system optimises all charging and discharging cycles in a best way which reduces the storage costs.






LE300 Technical Data Table ver01

made in germany logo 2 2

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