Power System Components

Just like a house, a lot goes into powering a camper van. The house batteries need to charge to store power so they can discharge to power the living systems.

Here is how all of the components in the RoamRig power upgrade work together so you can worry less and enjoy being on the road more in your Winnebago Revel. Keep reading to see how each component fits into the system.

If you have not already read it, we recommend starting with our Electricity Basics for Everyone blog post before reading this one.

DC-DC Converters take DC voltage/current from one source and change it to a different DC voltage/current for another source. During this conversion, watts are unchanged. If the converter is receiving 10A at 10V, that’s 100w (10A * 10V =100w). If the source needs 20V, then the converter will convert it to 5A (5A * 20V = 100w). 

Back to our line analogy (see this post), the DC-DC Converter receives a straight voltage line at one thickness and height and changes the thickness and height to a different one.

Solar Controllers are a fancy type of DC-DC converter. They take voltage from the solar panels and adjust it to match what the batteries need for optimal charging. 

• In a RoamRig system, the Kisae DMT1250 DC-DC converter is combined with an MPPT solar controller. It controls charging from the stock Mercedes chassis alternator AND the solar panels. Neither the alternator nor the solar panels produce electricity at the voltage that the batteries need to charge, so the DC-DC converter adjusts the voltage to correctly charge the lithium house batteries.
  
  

Inverter/chargers are an even fancier kind of voltage converter that have another trick up their sleeve: they take wavy electricity (AC) and convert it to straight line electricity (DC). This is what happens when you plug your van into shore power and charge your batteries. Shore power is AC power, and the inverter converts it to DC power to charge. 

The inverter charger is bi-directional. It can also use DC power from your batteries and convert it to AC to power things like your induction cooktop, air conditioner, and other items that plug into a household-style outlet. To do this, the inverter must be turned on. Running the inverter consumes a little bit of power to convert DC to AC voltage. We strongly recommend leaving your inverter off unless you actively need AC power so that you do not throw the lost power away.

• RoamRig installs a Kisae BIC1230100 inverter in our power systems. It can supply up to 3000w continuous AC power from your batteries to run appliances. It can also convert AC shore power to DC power to charge batteries at up to 100A at 12.8V DC.

Battery monitors display the real-time status of your electrical system. Monitors estimate the state of charge of your lithium house batteries (read more about that estimate here). They also directly measure the voltage of the batteries and how much current is flowing in/out of the system.

When load is high, you will see a large NEGATIVE number for amps (electricity leaving the batteries). When charging is high, you will see a high POSITIVE number for amps (electricity coming into the batteries). If you remember our lesson about how amps and watts are related, you will also notice that when amps go up, watts go up, and vice versa.

• RoamRig uses the Victron BMV712 in all our power systems to check current flow and voltage into/out of the entire bank of batteries. The monitor calculates a state of charge for the entire battery bank based on these measurements and displays it on the Victron gauge and in the Victron app.
• Some batteries (like Lithionics batteries) have internal monitors that check current flow and voltage into and out of each individual battery. The monitors will calculate a state of charge for each battery based on these measurements and display it in the Lithionics app. 

For Revels with a secondary alternator, RoamRig installs and highly recommends an external regulator. The regulator controls the auxiliary alternator to output a specific voltage for charging your house batteries. Read more about external regulators on our blog.