Before electronic dual battery management systems (which are by far the best devices to isolate multi battery systems) there were only two choices for battery charging and isolation; manual/solenoid or diode. 

Manual Isolators

Manual Isolators are a device that switches the connection of a battery on and off. They have a very simple manual switch operation.

Solenoid Isolators

Solenoid Isolators are like an automatic switch. When power is fed into the switching terminal of the solenoid, the solenoid is switched on, allowing the power to flow between batteries. This allows you to start from both batteries and winch from both batteries. The batteries are charged together in parallel when the solenoid is switched on. When the solenoid is switched off only the main battery will charge.

Diode Isolators

The Diode Isolator completely isolates each battery circuit from the other so when one battery is used (even if it is dead) and other, will remain fully charged.

Electronic Isolators

In the mid 1980's Piranha introduced the first electronic isolator (DBE100S now obsolete) that revolutionised the way dual battery systems worked. Electronic battery management systems now work on the same basic principals as this revoluntionary product. 

Electronic Isolators ensure that the main starting battery is charged before connecting the auxiliary battery. It does this by monitoring the voltage in the main battery. When the voltage in the main battery reaches a predetermined threshold, the isolator switches to charge the auxiliary battery. It will also disconnect the auxiliary battery from charging if the main battery voltage drops below that of another predetermined threshold. Thus this system ensures that the main starting battery is always given charge priority and therefore the risk of having a flat main battery is greatly reduced.  

   DBE180S

Piranha's DBE 180S Electronic Isolator is a 180 amp unit with full spike/surge protection and solar input to charge the auxilary battery. With a plastic/nylon case, sealed relays and special coatings to resist corrosion and water damage, this is the toughest isolator Piranha (or anyone) has ever built! 2 Year warranty with a 5 year option if fitted as part of a complete kit by a Piranha Technician.

Features

One way flow-Only allows power to flow in one direction, charging the main battery first, then the aux battery.

Electronic current limiting-No more fuses or bi-metal circuit breakers. Intelligent current limiting circuit isolates auxiliary battery if accidentally overloaded.

Easy to install- Includes everything you will need to install with full cable kit, earth strap, heat shrink, brass terminals and all hardware.

Less joints- Less joints means less potential problems, ie.voltage leaks, incorrect earthing etc.

Fitted to any vehicle- Diesel, petrol, EFI, turbo with either internally or externally sensed voltage regulator.

Battery choice- Allows the use of dissimilar batteries ie.size, type, age or design.

No interference- With existing vehicle or boat wiring. No effect on vehicle warranty or original wiring.

Spike & surge protection- For EFI, petrol and diesel vehicles as well as protection for UHF/CB, phones and GPS.

150/180 amp capacity, different amperage units to suit the job.

Plug in options- The DBE180S isolation system is a state of the art piece of equipment offering two unique 'plug in' features:

Monitor Plug- A battery monitor option. Output to an LED monitor inside the vehicle, simply select which battery you want to know the status of and the monitor will tell you.

Solar Input Plug- Direct input from solar panel (max 50w) with the LED monitor on the DBE180 telling you if charging from solar, alternator or both.

Warranty- 2 year unlimited km warranty or 5 year unlimited km warranty when purchased with full fitting kit (isolator, battery, battery cradle) and fitted by an authorised Piranha installer.