Thread: DC/DC chargers, How do they work and do you really need one.

Originally Posted by Old Farang

https://enerdrive.com.au/2014/09/11/dc-to-dc-converters-explained/

It is not surprising that confusion arises! Exactly WTF are they trying to say here:

Hence a step-up dc-dc converter will reduce the input current level to a lower value at the output in the same proportion that it raises the value of the input voltage

Hence a step-up dc-dc converter will reduce the input current level to a lower value at the output in the same proportion that it raises the value of the input voltage.

Hence a step-up dc-dc converter will reduce the input current level to a lower value at the output in the same proportion that it raises the value of the input voltage.

Yes, it sounds daft, but it is not really as daft as it sounds. The DC-DC converter doesn't MAKE any electricity, it CONVERTS it. Therefore the ELECTRICAL POWER at the output will be the same as the ELECTRICAL POWER at the input, less a small percentage for losses. Power is made up of VOLTAGE multiplied by CURRENT. There will be power (voltage and current) at the input, and power (voltage and current) at the output. The converter in effect converts one lot of power (voltage x current) into a different lot of (equal) power (voltage x current) but the RATIO of voltage to current changes between input and output. Thus the output typically will have MORE voltage but LESS current at the output than on the input. The power is the same.

This allows for compensation for voltage dropped between the alternator and the DC-DC converter, and it also allows for tailoring of the output voltage to suit different battery chemistries.

The current spec for the DC-DC converter is simply a measure of how powerful the converter is, but it has the side benefit of LIMITING the amount of current taken from the alternator, thus helping to prevent premature alternator failure.

The current spec for the DC-DC converter is simply a measure of how powerful the converter is, but it has the side benefit of LIMITING the amount of current taken from the alternator, thus helping to prevent premature alternator failure.

Really? Hmm, I'm sure drivesafe will have something to add to that!

I am more than well aware of what it is designed to do. My post refers to writing gibberish about something that can be explained in simple term without confusion.

Originally Posted by Old Farang

Really? Hmm, I'm sure drivesafe will have something to add to that!

Nop, his B/S knows no bounds, and I’ll not waste everybody’s time addressing it.

I totally agree with your post. Their “statement” is more confusing than helpful!

Originally Posted by Old Farang

Really? Hmm, I'm sure drivesafe will have something to add to that!

I am more than well aware of what it is designed to do. My post refers to writing gibberish about something that can be explained in simple term without confusion.

Sorry Old Farang, when you wrote "It is not surprising that confusion arises! Exactly WTF are they trying to say here:" I thought you were asking a question.

Originally Posted by Silenceisgolden

The current spec for the DC-DC converter is simply a measure of how powerful the converter is, but it has the side benefit of LIMITING the amount of current taken from the alternator, thus helping to prevent premature alternator failure.

And therefore taking a lot longer to charge a battery in a low state of charge,than using a VSR.

In a modern vehicle,such as a D4 with a 180Amp alternator,it would take a hell of a lot of current to overload the alternator.Even so the alternator will limit the current.If it did happen,this would only occur for a short time,so the chance of damaging the alternator is more than likely negligible.

The main cause of failure of alternators is heat,dirt,mud and water,and failure of the diodes,over time.

Originally Posted by scarry

And therefore taking a lot longer to charge a battery in a low state of charge,than using a VSR.



The main cause of failure of alternators is heat,dirt,mud and water,and failure of the diodes,over time.

Absolutely correct!

Errr... Scarry, what causes the diodes to fail?

Originally Posted by Silenceisgolden

Absolutely correct!

Errr... Scarry, what causes the diodes to fail?

Wear and tare

Originally Posted by scarry

Wear and tare

Hint - google "causes of diode failure in alternators".