Battery layout using a Duo Charge
The
Balmar Digital Duo Charge is the key part of my preferred way of doing a high performance battery layout for most applications. In this layout the start and house batteries are kept completely separate. The start battery does the starting only, the house battery does everything else. All of the charge sources lead directly to the house battery, including battery chargers, the alternator, and any wind or solar chargers. The only thing that charges the start battery is the Duo Charge.
Advantages of the Duo Charge system
Maximum efficiency - all the charge goes where it is needed.
Minimum waste - no battery isolators to get hot and waste energy.
Easy to understand - no operator input needed.
Easy to monitor - put a full amp hour meter on the house battery only, just a voltage readout is needed for the start battery
Temperature and voltage sensors always in the right place
Start battery does not get overcharged
Disadvantages of the Duo Charge system
A little more expensive than the other options.
If the Duo Charge fails you are back to the manual system
On big engines with electric air heaters for cold weather starting the Duo Charge will not provide enough power to run the heater and the start battery had better be big enough to do this for the required duty cycle.
How it works
The Duo Charge provides a measured charge to the start battery from the house battery whenever the house battery voltage is 13 volts or above. The measured charge to the start battery is just enough to keep it charged, it can be temperature compensated if needed, and is only done when the main battery is being charged. As the start battery doesnt do much work this arrangement helps it to last a long time while keeping it completely separate, charged up and available for starting.
All of the other charge sources go directly to the house battery which is where the loads are. Its a very simple straightforward easy to understand system. The house battery gets monitored rather carefully, the start battery just needs a check with a voltmeter from time to time to make sure it is OK.