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Dual Battery Systems

Dual Battery Systems are an essential part of many peoples’ set up, as they give a dedicated power source for items such as fridges, lights, compressors and inverters without risking the starting battery. However, gone are the days of a simple solenoid system to isolate and charge the secondary battery. With the introduction of smart charging alternators, AGM and Lithium batteries and the addition of solar dual battery systems have become far more complex and require expert advice to get right. The TJM 4×4 Megastore team understands modern charging systems and can help guide you into getting the most out of your dual battery system. 


Here at TJM 4×4 Megastores we work with you to understand your needs and your desired outcomes and work with you to develop a solution that will meet your expectations. 

Dual Battery Isolation Systems

There are a number of options when it comes to Isolators for your dual battery system. One key factor to selecting is the type of vehicle you have but also equally important is how you are going to use the system.

  • TJM 4×4 Equipped 25amp and 45amp DC/DC
  • TJM 4×4 Equipped IBS
  • TJM 4×4 Equipped DCDC DBS
  • Enerdrive DC DC 40+ Amp
  • Redarc DC DC

Battery Options

There are three main options when it comes to the battery you select for your dual battery system. These options are lead acid deep cycle (Good), AGM (Better) or Lithium (Best).


Lead acid deep cycle batteries are suitable for under bonnet or in an open tray or tub. They cannot be fitted inside a cab or canopy due to the gases that are discharged while the battery is being charged. These batteries are the cheapest option however are susceptible to reduced lifespan if not run through full discharge and recharge cycles on each use.


AGM batteries are the most popular option when fitting dual battery systems. They are suitable for under bonnet, in cab or canopy mount as they do not discharge any hazardous gases when being charged. AGM batteries are generally more durable for partial cycle use (part discharge than recharge).


Lithium batteries offer a number of significant advantages such as reduced weight and increased capacity over the other options. They cannot however be fitted under the bonnet of the vehicle due to heat restrictions. They are the most durable when it comes to partial cycle use.