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


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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

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