DC-DC Converter over 48V - Recommendations

[llile]

I'm running a 72v (nominal) battery pack, and I'd like to put a DC-DC converter on it to run some lights and accessories. What have other people used? So far the Google Gods have not smiled upon me.

Ebikes.CA has a real nice DC-DC converter but it only handles 48V input.

I can buy aMean Well power supply but above 48V they are quite expensive and bulky.

What would I like to do with it?

#1 priority - running some lights. After checking into Justin's fabulous but pricey LED cycle illuminators , I am thinking about building my own. (I've built a lot of electronics so this isn't a formidable task. Separate thread will detail it) For the lights I will need about 12V and 350-400 mA.

#2 Priority It would be really keen to have a 5V USB plug that would charge my cell phone. A small 12V-5V DC-DC regulator after the main one would be fantastic.

#3. a nice fat 12V plug for any 12V accessory. This is possibly 500W of power though, might get pretty expensive to convert the juice...

If the batteries were just a little lower voltage, a MEan Well NSD05-48S12 DC-DC converter would do the job, for $12. I already have some of these. This little job is rated at 72 volt max input, but a 24S LiFEPO4 could run over 80V+ briefly. Hmmm..

Have you used a DC-DC converter for a 72V+ battery?

 

[dnmun]

you can try using a wall wart. the 72V lifepo4 pack charges up to almost 90V not 80.

 

[friendly1uk]

The meanwell is only 5w. It wouldn't be a lot of use.
You might not like the idea, but this one is less money delivered and 10x more powerful. However.... 60v max input http://www.ebay.co.uk/itm/DC-DC-Step-Down-Voltage-Power-Regulator-Module-Converter-YDS-505-Adjustable-/281074167765?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item4171536fd5

I'm thinking a little outside my box here, so hopefully your own experience can see if what I'm about to say is possible.

To produce a more reasonable 50vdc for the above device, could you use an lm317 and 2n3055 combination? If the 317 just drives the 2055 it's consumption might be steady enough and low enough to power the 317 from a voltage divider. The output might be all over the shop, but as long as it remains between say 15v and 60v the above device should sort it out.

317 circuit for consideration: http://www.bristolwatch.com/ele/lm317.htm

 

[Doctorbass]

This has been discussed alot of time on E-S...

if you take time and search a bit you will find that we use some regular AC-DC 12V 5A transformer ( switching power supply) availlable from ebay for about 10$ shipped or 5$ at any local PC surplus store.

Few years ago i discovered that these AC input power suppy ALSO accept DC at the input and with voltages as low as 25V sometime! I made some post about that :wink: i'm using this method for all my ebikes projects now. What is great is that they can sometime take any voltages from 25 to 350Vdc at the AC normal 120V input

http://www.ebay.com/bhp/12v-5a-power-supply

Doc

 

[friendly1uk]

As low as 25v ?
I also came up with the idea, but most want 85vac upwards. I expected a dc of more like 100v would be needed, So I only spoke of it to a chap using 120 odd volt.

I have seen it spoke about between then and now, but only that it can be done. I couldn't find anything on the subject.


I guess the op only wants phone charger levels of power, And they are 10 a penny. Trial an error might find something laying about the house

 

[Doctorbass]

As low as 25v ?
I also came up with the idea, but most want 85vac upwards. I expected a dc of more like 100v would be needed, So I only spoke of it to a chap using 120 odd volt.

I have seen it spoke about between then and now, but only that it can be done. I couldn't find anything on the subject.


I guess the op only wants phone charger levels of power, And they are 10 a penny. Trial an error might find something laying about the house

dont be fool by the 85 to 250VAC... if you put DC like 36V at the Ac input it should work

Doc

 

[llile]

Thanks Doc- I'll try a few wall warts I have laying aroundand see if they don't work on dc.

I searched for this on the forum but couldn't find anything under the search terms I happened to use. happens a lot here.

Of course the other method used in electric cars isto use a 12v "cabin battery" separately charged. This could provide a lot more power for 12v accessories, but could result in trouble if the battery for the lights runs out in the middle of a night run.

I'd like the 12v system to be really efficient whichh is why I'm not going to use a &imple linear regulator.

I found an old Mean Well wall wart that makes 9v at 72 vdc, even works down at 40v. Most of the ones out of my junk pile didn't work on dc. 9v will drive 3high power leds quite adequately.

I'll keep looking for one that does 5v. I have some already set up with a usb port, if they work on dc that would be sweet-

 

[el_walto]

You should be able to use almost any old printer/scanner/laptop power supply etc, as long as it's not the old big heavy kind with the transformer.

 

[agniusm]

I have bought some of these in 72V, 36V fashion:
http://www.ebay.com/itm/DC-DC-Conve...436?pt=LH_DefaultDomain_0&hash=item1c2bc439d4

i like them as they are water proof and have nice 20A output.

 

[Ariane]

Thanks Doc- I'll try a few wall warts I have lying around and see if they don't work on dc.

Lille you miss the point many people use AC power switching power supply and we feed them with DC instead of plug in them in AC outlet. Like Doc explains at about 36 Volt DC this AC switching power supply output 12 Volt DC at the exit and you can put 100 Volt DC at the enter if needed then perfect for your project.

Good day!
Black Arrow

 

[Bison_69]

Hi Llile,

The Doc idea is so far the best and inexpensive way to go....

But in case you prefer to spend on a very high precision DC-DC converter here is a company which sell at Digikey, Mouser and so on...

Low Amp.
http://www.cui.com/product/power/dc-dc-converters/isolated-chassis-mount/vyc30w-t-series

From 10 to 600W
http://www.cui.com/catalog/power/dc-dc-converters/isolated-chassis-mount

Here is also a 12Vdc plug-in waterprrof USB connector to supply external devices
http://www.prodctodc.com/dc-12v-to-...erter-car-power-supply-buck-module-p-137.html

 

[llile]

Thanks Doc- I'll try a few wall warts I have lying around and see if they don't work on dc.

Lille you miss the point many people use AC power switching power supply and we feed them with DC instead of plug in them in AC outlet. Like Doc explains at about 36 Volt DC this AC switching power supply output 12 Volt DC at the exit and you can put 100 Volt DC at the enter if needed then perfect for your project.

Good day!
Black Arrow

Yep, that's what I tried. Out of 5-6 wall wart AC-DC powersupplies in my junk box, I found one that worked OK on DC. Although my batts are nominally 72 volt, it worked OK all the way down to 30-40 volts. It is only a 9V power supply at 2 amps, but I can run my lights (LED light build separate thread). I'll keep combing for a junk AC-DC power supply that runs on DC for some 12V juice.

 

[friendly1uk]

Just looking at the 60v reg I got (link above). The capacitors across the supply are 50v. Thus, the lump might take 60v, but the module as bought is for 50v not 60v.

 

[Bor_Ed]

I just ordered http://www.zenid.com/converter.htm and the thingy is still in the mail.
I rather buy from 'stores' than ebay and the price wasn't that bad including shipping to Finland.

 

[cal3thousand]

I just ordered http://www.zenid.com/converter.htm and the thingy is still in the mail.
I rather buy from 'stores' than ebay and the price wasn't that bad including shipping to Finland.

You can buy a DC-DC that DoctorBass recommends at a 'store'. He just put up eBay since it is cheap and accessible to most.

 

[Rambo Ruckus]

doc, youyre talking about this style power supoply? and you just hook it up to +- 111v or so, around 30s, then it will produce out the output 12v dc?? im just curious on the style, because I can get these types for free at my town recycling center.

 

[izeman]

only way to know if it works is to TRY IT OUT. some work, some don't. but @100v almost all of them should work. it may be difficult to find a ps to give full current when fed with 12s lipo (44v nominal). some work, some don't, and some are not ablle to provide full current as printed on the case.
btw: what to you mean by "style"? how would you want to know what it looks like in the inside from looking at the case?

 

[Rambo Ruckus]

I meant as opposed to the psu looking converters. these I have laying around and at a local recycling center they have them. was just curious.

 

[Rambo Ruckus]

as opposed to this "style" I mean.

 

[Raphael303]

For those wondering the same thing. DC DC converters, if you don't want to (ab)use AC/DC converters that can put up with a 72V battery, something 20s Lithium ion 18650 or more are available, but rather expensive.

Here some types that I found in the 60-80 euro range:

Traco TEN 20-7212WIR (43V-160V, 20W, 1.67A, 12V)
Traco TEN 8-7212WI (43V-160W, 8W, 0.66A, 12V)
Murata RUW15SL12HC (16-160V, 15W, 1.25A, 12V)
Murata RUW15SL12C (16-160V, 15W, 1.25A, 12V) (bit cheaper than the above)
XP POWER RDC20110S12 (55V-176V, 20W, 1.65A, 12V)
XP POWER RDC2072S15 (36V-140V, 20W, 1.33A, 15V)

You can find them in various places, depending your location, like farnell, mouser, distrelec, reichelt, digikey etc. There are plenty more in the series of each, however they are even more expensive.

If you do not want to spend this much I guess your only option is the "ab"use mentioned above.

 

[ridethelightning]

doc, youyre talking about this style power supoply? and you just hook it up to +- 111v or so, around 30s, then it will produce out the output 12v dc?? im just curious on the style, because I can get these types for free at my town recycling center.

yep thats what i use, itl work.
must get the input polarity right, trial and error is ok. rtl

 

[alsmith]

doc, youyre talking about this style power supoply? and you just hook it up to +- 111v or so, around 30s, then it will produce out the output 12v dc?? im just curious on the style, because I can get these types for free at my town recycling center.

yep thats what i use, itl work.
must get the input polarity right, trial and error is ok. rtl

The first ebay one I tried didn't have input protection and wasn't marked- I got sick of waiting for an answer so guessed- wrongly.

 

[DasDouble]

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