Why do you need a DC-DC charger for RV

If you have researched the dual-battery system for your camper van, motorhome or caravan, chances you have come across a DC-DC charger. They are the important part of any dual battery system. Before you are making decision to use them, you need to know what do they do and how to use them.


What is the DC-DC charger?

DC-DC charger is the intelligent method of on-board charging in safe, fast and regulated way. It takes power from alternator while the vehicle is running and optimizes the charging to get most effective power for the house battery.

Alternator provides a relative stable voltage and current for start battery and house battery. Unlike the start battery, the deep-cycle designed house battery (auxiliary battery) needs a multi-stage charging profile so that it can be fully charged. The DC-DC charger converts the voltage from alternator to a higher voltage with the optimal current so that the charging can be correctly operated.

 PD series DC DC MPPT charger 50amp

DC-DC charger will monitor the voltage of start battery. As soon as the vehicle is on, the voltage on start battery will increase and the DC-DC charger will start to charge the house battery. When the vehicle is off, alternator stop works, the voltage on start battery will drop and it will disconnect start battery and house battery. In this situation the DC-DC charger acts the isolator for start battery and house battery for not draining the start battery.


Why cannot the isolator play well?

Battery isolator can not work effectively, because more and more vehicles have the smart alternator for concerning about fuel consumption and emissions. Therefore, the charging voltage will be dropped regularly which will be lower than isolator’s cut-off point. At this moment even the vehicle is on, the house battery charging will be stopped.


Additionally, the isolator cannot provide the multi-stage charging. The alternator only gives a stable voltage onto the house battery which is only able to charge the battery to 80%.


What makes Popsail DC-DC charger be outstanding

MPPT solar charge controller combined

There are 30Amp and 50Amp two models, With MPPT Solar Charge Controller Combined, they give another charging solution to your house battery which does not need run your vehicle. For example, if your camper van is parked in the camping land for a couple of days, without mains charging and alternator charging the house battery power will be run out quickly. But with our DC-DC charger the house battery can be charged. In this way you can keep batteries charged even when you are not driving and engaging your alternator.


“Fuel Saving” Design

Most DC-DC charger only uses alternator charger without solar charge circuit. You can also find a few DC-DC + MPPT charger on the market. But most of them use alternator charging as the first priority, when the vehicle stops then the charger turns to solar to charge the battery. This means your alternator will always take charge of charging both start battery and house battery. The fuel consumption will get increased if your battery has almost seen bottom.

Popsail PD DC-DC charger always use the solar to charge the batteries. When the charge power value gets lower than its 50% rated power and then DC-DC charger turns to alternator charging. It does not always take power from alternator to reduce the output duties from alternator.


How to choose a DC-DC charger

PD DC-DC charger is compatible most common deep cycle batteries and Lithium batteries.

If you are going to use it for your lithium batteries check the battery input current firstly.


Once you have determined the type of your batteries, you need to select the suitable model for your batteries.

For the lead-acid batteries (such as AGM, GEL), their charge current is 0.2C~0.5C (20%~50%) of the battery capacity. For example: 100Ah battery need an 20A charger at least.

For this PD DC-DC charger:

PD30(30A DC-DC charger): <150Ah Lead acid batteries

PD50(50A DC-DC charger): <250Ah Lead acid batteries


For Lithium batteries, generally it requires 0.3C~0.5C (30%~50%) current rate of the battery capacity.

PD30(30A DC-DC charger): <100Ah Lithium batteries

PD50(50A DC-DC charger): <160Ah Lead acid batteries


Abundant power supply is essential for your outdoor living, this PD DC-DC charger now provides you the option of the good power supplement. Make your battery charging be easier than ever.

>> Calculate The Voltage Drop