Circuit for DC to DC Convertor. 1

[mooimooi]

Hi
I need to convert a DC 200V supply to 24VDC,10 to 15 Amps for battery charging purposes in a boat. Is there any commercially available converters available?
WOuld appreciate also if anyone can provide me a schematic to build one.
Thanks in advance..

 

[felixc]

You may want to consider a regular AC switcher. The first thing that these switchers do, is to rectify the AC into a DC then convert it to the required DC voltage. Using a DC at their inputs will do the same effect. The DC will just flow through the diodes up to the DC filters. The issue then becomes to find an AC-DC switcher that does work over the full range of 120 to 220VAC, as your DC source fits right in between these two. Check at places like Condor or PowerOne if their switchers operate over the whole range, or if they auto-switch between the two ranges. You need one that does operate within the full input range. That would make a reliable power supply, inexpensive, without the need to build one. Building a high-power switcher, quantity one is a hasardous task that can do a lot of damage and harm.

 

[lcsjk]

A 120 VAC switching power supply steps up the voltage to either 170 volts or 340 volts based on its topology. A 220 vac input PS rectifies the input to a voltage between 280 volts and 310 volts. So if you want to use a commercial power supply, you will need a unit with only one input capacitor. Some charge one capacitor on the positive half cycle and the other on the negative half cycle.

If you want to build your own, you might want to consider a DC-DC converter such as those made by VICOR and their competitors. Some can work directly off the 200 VDC.

Actually, it might be easier and lower cost to get a surplus power supply from Marlin P Jones or some other surplus company providing you have 120 or 220 volts AC available.

 

[Warpdrive]

Mooimooi, et. al.

I've worked boats most of my life. On a boat, alternating current is considered a luxury. As the sea is a harsh mistress, you may want a more robust charger.

Lots of companies make off-the-shelf DC-DC converters of the type previously mentioned, as well as AC switchers. The advantage of the AC switcher is being able to seamlessly use either. I usually do business with these producers:

http://www.vicor.com

http://www.astrodyne.com

IMPORTANT --
Keep in mind these types of supplies do not have any "gas gauge" or automatic cutoff circuits to prevent battery overcharge. They are primarily meant to service electronics needing DC or DC motors. I assume you're using lead-acid deep cycle batteries. If they are mounted aboard your boat where an acid leak from overcharge could "liquidate" the craft, I highly recommend you have an automatic cutoff with a charge gauge. This will cost a little more up front for the monitor circuit and control transistors, but is worth the investment in terms of the boat's seaworthiness (read:"insurance premium&quot, resale value -- and your peace of mind.

While this application can be quickly met using ordinary car battery chargers, a sealed, solid state approach will fit a boat better.

Enjoy.

Warpdrive

 

[peebee]

Maybe a separate 120-volt inverter & 120vac/24vdc battery charger would give you more flexibility.

Where are you getting 200vdc from anyway? Just curious.

 

[mooimooi]

To all.
I thank all of you for your contribution. I must say that I have gained very useful information from your excellent feedback.
Thanks and Joy to you.