Everything You Need To Know About DC/DC Chargers

Victron Energy have the Orion-tr smart range that are DC to DC adaptive 3-stage battery chargers, with built-in Bluetooth connectivity. They are available with galvanic isolation or without (non-isolated).

What is the difference between isolated and non-isolated?

In an isolated converter, the input and output stage have separate grounds. The isolated version has a separate, galvanically isolated input and output (typically achieved by using a transformer) . See diagram below.

 

Whereas in a non-isolated converter, current is able to flow directly between the two sides as they share a common Negative connection ( In an Automotive application,  this connection is frequently referred to as the Earth, Chassis or Grounding connection). See Diagram below.

 

In some cases, it is necessary to route signals across the isolation boundary. This is particularly necessary with regulated devices where a feedback signal is required. To preserve the isolation, these signals must also be isolated.

What do I need for my application?

In most applications though, a non-isolated unit will do the job. It is also more cost effective than the isolated version. Some applications require isolation for safety reasons, along with many factors.

Pros of Non-isolated Chargers

• Cost savings in general
• Possibility of smaller size
• Quite often higher efficiency

Pros of Isolated chargers

• Safety compliance
• Breaking of ground loops
• Floating output and level shifting
• Electrolysis mitigation

 

What about a DC DC charger with a combined MPPT?

Victron energy do not have a combined unit like this, and for a few reasons..

Victron have a great range of MPPTs to choose from, here are some pros listed on keeping the two units separate.

1.Pro Redundancy - The likely hood of both units going faulty or suffering from an incident causing failure is cut in half. If for some reason you ever need to do a warranty claim or a repair on the combined unit, you will have to go without a DC charger & the MPPT until the problem is resolved.

2.A Faster Charge - For example:

A single 40 Amp integrated unit with built in MPPT is limited 40 Amps (Slower Charge)

30Amp DC/DC Charger &  30amp MPPT(separate) = 60amps (Faster charge).

3.Limited configuration

Most integrated DC/DC Chargers with a MPPT have a low solar input voltage limit of say 45 Volts. This limits the configuration options and greatly limits the solar panel range that is compatible. Also, this means there is a higher possibility of over voltage failure.

In conclusion, in most applications it is far better to use a separate DC/DC charger & Solar MPPT charger rather than a combined all in one unit.