Looking for a 48v-12v converter.

[my t30]

Hi guys. Another beautiful day of 40 deg weather in Ontario.

So upgrading my Dads off-grid 12v system to 48v and I cant seem to find any name brand 48-12v converters. I've found a few Chinese brands but no reviews and not much specs on them either. Anyone use anything that they would recommend? I was thinking in the range of 50A 12v output or thereabouts.

Thanks in advance.
Philip

[mike90045]

Try these in a search engine
600w dc-dc converter 48v-12v
or
48v to 12v converter golf cart

These will give some other ideas than from china.    Vicor makes some good stuff, if you can find modules on ebay thats good.

[my t30]

Thanks Mike. I looked at some of the Vicor stuff and it looks promising. Found this one, (http://www.digikey.com/product-detail/en/IB050Q096T70N1-00/1102-1047-ND/2776211). A little pricey, but all the specs look good. A little too good actually. The input voltage, output voltage , high efficiency, low standby current all seem a little to good to be true. I feel like I'm missing an obvious reason why I cant use it.

I also found some 20A and 60A golf cart converters on ebay. Unknown brand, but I emailed them asking about no-load draw(kind of a big thing in my case).
http://www.ebay.com/itm/WaterProof-48V-to-12V-20A-240W-DC-DC-Step-DOWN-Power-Converter-Regulator-/301226037668?
http://www.ebay.com/itm/GOLF-cart-DC-Converter-Electric-Car-Voltage-Reduce-48V-volt-to-12V-60-Amp-EZGO/111399010089?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D33024%26meid%3D0eb531e0734c45c29c4676999db07e23%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D301226037668

No idea why the second link is so long.  I'm still interested in hearing what anyone else uses on their 48v systems. Thanks so much to anyone who takes the time to read this. Sorry for stealing 30 seconds of your life. 

Philip

[mike90045]

vicor makes top of the line stuff, and I would be confident of their data sheets, heatsinking is critical for it.

[tecnodave]

my t30,

Samlex makes some converters that are 48-12 volt both common neutral ( buck-converter) and fully isolated (DC-DC inverter) . I'm using their SD-30 18-32 volt to 13.6 volt buck converter and the
IDC-360-12 20-35 volt to 13.6 volt  fully isolated converter on my 24 volt system. I use the IDC-360 for communications gear as it isolates the hum,noise, and trash from inverters, controllers, etc, far better than the more common buck converters

td

[my t30]

Thanks technodave. Somehow I could not find 48v ones on the Samlex website before. Looking into them now.

[my t30]

So after a lot of looking around, I am going to give ViCor a try, this one specifically(http://cdn.vicorpower.com/documents/datasheets/vibrick/ds_IB050E120T32N1-00.pdf). I'm going to run 2 of them in parallel for load sharing and redundancy, and have a small heatsink and fan blowing across them . I cant find any kind of sockets for them so it looks like I'll just be soldering them unless someone else has a better idea.

Of course being the moron that I am sometimes, the first thing i did was drag a live 48v wire across the surface of the board while testing it and blew a few tiny components off of it. I'll give a shot at fixing it but doubt i'll even be able to solder something that small. Chalk it up to the cost of research i guess.

If anyone can think of any problems with this setup i would love to hear them. I will update this thread in a few weeks to let you guys know how it works out.
Thanks again to mike for recommending ViCor.

[Vic]

Hi Phillip,

I have not used any voltage converters in this type application.

The only major issue that presents itself from the Data Sheet that you linked,  might be the Max Vin seems to be speced at 60 V.  Generally,  this would be too low for Flooded batteries,  and possibly also for some AGM batteries.

For Flooded batteries,  the range of temperature compensation on cool/cold batteries,  and for EQing them could/would often be expected to exceed this spec,  IMO.

Possibly you could insert a few rectifier diode-drops in the Vin lead to the converter ...  perhaps.

FWIW,   Good Luck,   Vic

[my t30]

What is the recommended charging voltage for batteries? The batteries I am going to be using are 8 Crown cr-330's in series . The datasheet voltage is a little confusing to me, but from what i can see the cells need to be charged at 2.37v per cell(56.88v overall). Temp com is 3mV/C, So at -30C that would be 57.055. I realize i would probably have to turn the converter off while equalizing. But equalizing is more of a monthly thing, I think?

This is what i got from the datasheet, but i could be mis-reading/understanding it.

Thanks so much, Philip

[Vic]

Hi Phillip,

Those CR-330s are Flooded batteries.

Am sure that you are using data from this Data Sheet:
http://www.solar-electric.com/lib/wind-sun/Crown-CR-330-specs.pdf

The recommended charge parameters are for Grid charging,  and in Electric Vehicle applications,  at that.

You are correct about the recommended Absorb voltage (Vabs) from that data.

However, to me,   for Flooded batteries that run 1.275 SG electrolyte,  this is simply too low,  for charging from Renewable Energy (RE) sources,  like Solar,  in off-grid applications.

Assuming that the application is off grid,  with Solar as the primary charge source,   your Vabs could easily approach 59 volts,  before temperature compensation at 3 millivolts per degree C,  per 2 V Cell  --  Crown's recommended compensation.

Cold batteries could easily see  Vabs above 60 volts  with the recommended compensation of --0.72 volts per degree C for all 24 Cells in series.

One of the good reasons that you may need a fairly high Vabs for these batteries,  is that Solar days are fairly short,  and if one is trying to fully-charge batteries within 3 - 5 hours,  the voltage often needs to be increased,  somewhat above recommended settings to accomplish this.  In the Far North  the good sun days can short,  as you know,  in Winter,  at least.

Many sites will only have an average of  3 - 4 hours of intense sun,  which is where most power production occurs,  depending on shading and local conditions,  etc.  The Summer conditions there may have considerably more sun,  at  a good site.

FWIW,   Vic

[zoneblue]

If you decide to parallel them, be sure to calibrate the output voltages, otherwise they might fight, or least one will dominate.

[my t30]

If you decide to parallel them, be sure to calibrate the output voltages, otherwise they might fight, or least one will dominate.

From the data-sheet i was under the impression that nothing was needed to parallel them, other than the wires kept the same length all-round. Page 11 on the datasheet. But I could be wrong. How would iI go about calibrating the voltages as there is no adjustment on them?

[my t30]

Hi Phillip,

Those CR-330s are Flooded batteries.

Am sure that you are using data from this Data Sheet:
http://www.solar-electric.com/lib/wind-sun/Crown-CR-330-specs.pdf

The recommended charge parameters are for Grid charging,  and in Electric Vehicle applications,  at that.

You are correct about the recommended Absorb voltage (Vabs) from that data.

However, to me,   for Flooded batteries that run 1.275 SG electrolyte,  this is simply too low,  for charging from Renewable Energy (RE) sources,  like Solar,  in off-grid applications.

Assuming that the application is off grid,  with Solar as the primary charge source,   your Vabs could easily approach 59 volts,  before temperature compensation at 3 millivolts per degree C,  per 2 V Cell  --  Crown's recommended compensation.

Cold batteries could easily see  Vabs above 60 volts  with the recommended compensation of --0.72 volts per degree C for all 24 Cells in series.

One of the good reasons that you may need a fairly high Vabs for these batteries,  is that Solar days are fairly short,  and if one is trying to fully-charge batteries within 3 - 5 hours,  the voltage often needs to be increased,  somewhat above recommended settings to accomplish this.  In the Far North  the good sun days can short,  as you know,  in Winter,  at least.

Many sites will only have an average of  3 - 4 hours of intense sun,  which is where most power production occurs,  depending on shading and local conditions,  etc.  The Summer conditions there may have considerably more sun,  at  a good site.

FWIW,   Vic

Ya sorry I was going to post the datasheet. Thanks for looking it up. What would you say the recommended charging parameters be for off grid solar? Also are you sure its 0.72V/C and not .072V/C. Seems a little much to me.
And yes this is for off grid with solar as primary and generator as backup.

[mike90045]

If you decide to parallel them, be sure to calibrate the output voltages, otherwise they might fight, or least one will dominate.

Exactly, or sometimes there is a jumper from board to board to share the same setting resistor.  read the manual carefully.

[my t30]

If you decide to parallel them, be sure to calibrate the output voltages, otherwise they might fight, or least one will dominate.

Exactly, or sometimes there is a jumper from board to board to share the same setting resistor.  read the manual carefully.

Unless I missed something I have read it and the only thing I have to do to parallel them is keep the I/O traced the same length until joined.
But I am thinking of going next size up and just using a single one. I will have some other converter as a backup anyway.
Thanks everyone who read and posted.
Philip