Power supply for headlights and breaklights.

I'm working on a motorcycle and I would like to tie a headlight and break-light to the battery pack (LiFe/20 cell @ 20aH each) 60 volts all together. I'm wondering if anyone has suggestions on a good DC/DC regulator. I would like to have a 12 volt DC switching power supply (switching for the efficiency). It would have to take a 72 volt supply (battery pack topped out) and supply 12 volts DC at around 10 amps. I say 10 amps to be on the safe side. I don't think a break light and headlight would draw more than 10 amps. I'll probably add a 10 amp fuse just in case. Any help would be appreciated.

im using a very common switching psu from a laptop or cd player. they are a dime a dozen at recycling shops etc, but i think would be cheap bought brand new too.

they are actually for ac/dc but give em 72vdc and they seem to spit out 12vdc all the same.

there are 2 main types of these, the heavy dongles like on a lot of chargers...with the mains plug directly on the case these have a coil so dont work.

you need the generally slightly longer/flatter/larger and usually lighter type. typically 8v,12v,18v 24v dc output, 90w is the most powerful iv seen, but im sure you can get stronger ones, like this-

http://www.ebay.com.au/itm/AC-100V-240V-to-DC-12V-10A-Monitor-Screen-Power-Supply-Converter-Adapter-/161423634612?pt=AU_Laptop_Accessories&hash=item25959930b4

you can also run say 2x 12v lights in series on a 24v version.

led lights now days have huge output for the watts they use.
i have some 6 watt daytime driving lights-
https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=0CFEQtwIwBg&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DpRQA5o2dF_I&ei=zf72VKnMMobZmAXS5oKICA&usg=AFQjCNG9SQVDbhunTvYRm1R_EBvIFs17Kg&sig2=icl0jyYGOhq-RSMdwR65GQ&bvm=bv.87519884,d.dGY


http://www.google.com.au/aclk?sa=L&ai=CyVPdzf72VNmsNsLe8QX1-4KADtHEn5cH-cqj9ZYB4fXS25cCCAQQAiCZqNkeKAVgpcCjgKQByAEHqQIoZYc160WqPqoEJE_QXxew0doMtCRVizi3EU6SYAIFC6fsGkcj_m81O9Zh02i9jIAFkE7ABQWgBiaAB8md8jqIBwGQBwKoB6a-G9gHAeASqY-O6vvKlIhL&sig=AOD64_1Khqm3bpmYZr5k-m5J1Kv9CJbAVw&ctype=5&rct=j&q=&ved=0CCUQww8&adurl=http://rover.ebay.com/rover/1/705-139619-5960-0/2%3Fipn%3Dicep%26icep_id%3D62%26mtid%3D1797%26kwid%3D1%26crlp%3D40593704497_573061%26icep_item_id%3D261756544734%26itemid%3D261756544734%26icep_meta_categ_id%3D131090%26icep_etrs%3DN%26icep_epid%3D-999%26icep_ctlg%3D-999%26icep_cond%3DNew%26targetid%3D75085691617%26rpc%3D0.41%26rpc_upld_id%3D44458%26device%3Dc%26icep_cbt%3Dn%26icep_msku_flag%3Dn%26adtype%3Dpla

stupidly bright for 6watts.

i run 2 super bright led headlights and 2 cob lights and im sure i could run heaps more..

I wouldn't use stuff that is meant for other purpose. Here is one with mounting:
http://www.ebay.com/itm/Golf-Cart-D...665?pt=LH_DefaultDomain_0&hash=item3cc1c2b0b1

JamStrong said:

I'm working on a motorcycle and I would like to tie a headlight and break-light to the battery pack (LiFe/20 cell @ 20aH each) 60 volts all together. I'm wondering if anyone has suggestions on a good DC/DC regulator. I would like to have a 12 volt DC switching power supply (switching for the efficiency). It would have to take a 72 volt supply (battery pack topped out) and supply 12 volts DC at around 10 amps. I say 10 amps to be on the safe side. I don't think a break light and headlight would draw more than 10 amps. I'll probably add a 10 amp fuse just in case. Any help would be appreciated.

Click to expand...

Any of the small, cheap laptop power supplies that dont use a transformer will work. I used to use one intended for a IBM laptop in a golf cart. I put battery power to the AC input, and replaced the output plug with a cigarette lighter. Has worked for years.

oh i forgot to add, these supplies are often know as half-wave rectifier (swithmode)
this means you need to get the polarity right with the input.
doent seem to be a problem if you get it wrong(wont explode) but it will not have any output unless the input wires are round the right way, so trial and error.

i first used a small dc/dc converter, rated to 90v off ebay. it worked for about 5mins then splat.

the ac/dc one has been running for a month or so now, bought for 5 bucks at the recycle shop.

Thanks guys for the advice. I'll do a little more homework on what was posted.

By the way... I've found a few components that may do the trick. I was looking at switching power supplies and came across this:

http://www.mouser.com/ProductDetail/Texas-Instruments/LM2679SX-12-NOPB/?qs=sGAEpiMZZMsMIqGZiACxIYreuZyZ6HSrONXMRKVqR78%3d

The circuit would be dead simple and cheap. 2 of these in parallel would supply the 10 amps. I would just have to get the first part of the circuit to regulate the 72 volts to below 40 volts (using another switching power IC). the secondary circuit would include these bad boys. Can't ask for more with a 95% efficiency.

By the way, my profession is designing circuit boards. So making this from scratch isn't too much of a headache.

Shameless plug: I use JetPCB.com (not associated with them but they do a great job).

One last thing; I'm using a kelly controller. Does anyone know what current the 12V optional supply can handle. I know it's wishful thinking, but maybe... just maybe I can tie my lights too it? :/

interesting idea.
let us know if it works. would be a nice compact solution.

just getting say, 90v down to 12v is the trick..

JamStrong said:

Thanks guys for the advice. I'll do a little more homework on what was posted.

By the way... I've found a few components that may do the trick. I was looking at switching power supplies and came across this:

http://www.mouser.com/ProductDetail/Texas-Instruments/LM2679SX-12-NOPB/?qs=sGAEpiMZZMsMIqGZiACxIYreuZyZ6HSrONXMRKVqR78%3d

The circuit would be dead simple and cheap. 2 of these in parallel would supply the 10 amps. I would just have to get the first part of the circuit to regulate the 72 volts to below 40 volts (using another switching power IC). the secondary circuit would include these bad boys. Can't ask for more with a 95% efficiency.

By the way, my profession is designing circuit boards. So making this from scratch isn't too much of a headache.

Shameless plug: I use JetPCB.com (not associated with them but they do a great job).

One last thing; I'm using a kelly controller. Does anyone know what current the 12V optional supply can handle. I know it's wishful thinking, but maybe... just maybe I can tie my lights too it? :/

Click to expand...

lol, I use a similar one in my electric push scooter to run 12v LED head and tail lights... This is what I bought.. notice its two of them. http://www.amazon.com/gp/product/B009HPB1OI/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

works really well, very accurate voltage hold... but I wouldnt try to draw too much amperage through it. It says 3A max, but gets warm at 2amps. With the .75 amp draw of my LEDs, i can feel the chip warm without the heatsink, but it stays room temp with it. Based on all that, even with a totally different chip, I would be suspicious of a 5amp draw in the same package.

This is what I have been using for 8-9 months now. No problems, very inexpensive:

DC 24V/36V/48V/60V/64V/72V To 12V 10A Converter For Electric Storage Battery Car

Click to expand...

http://www.ebay.com/itm/DC-24V-36V-48V-60V-64V-72V-To-12V-10A-Converter-For-Electric-Storage-Battery-Car-/331045796298?pt=LH_DefaultDomain_0&hash=item4d13ddf9ca

JamStrong said:

Thanks guys for the advice. I'll do a little more homework on what was posted.

By the way... I've found a few components that may do the trick. I was looking at switching power supplies and came across this:

http://www.mouser.com/ProductDetail/Texas-Instruments/LM2679SX-12-NOPB/?qs=sGAEpiMZZMsMIqGZiACxIYreuZyZ6HSrONXMRKVqR78%3d

The circuit would be dead simple and cheap. 2 of these in parallel would supply the 10 amps. I would just have to get the first part of the circuit to regulate the 72 volts to below 40 volts (using another switching power IC). the secondary circuit would include these bad boys. Can't ask for more with a 95% efficiency.

By the way, my profession is designing circuit boards. So making this from scratch isn't too much of a headache.

Shameless plug: I use JetPCB.com (not associated with them but they do a great job).

One last thing; I'm using a kelly controller. Does anyone know what current the 12V optional supply can handle. I know it's wishful thinking, but maybe... just maybe I can tie my lights too it? :/

Click to expand...

Please excuse my newb-ness if this is a bad idea but would it be possible to wire two of these switching regulators in series on the input, and then parallel on the output? So then let's say your battery pack is at 80V, the regulators will each see 40V at the input, and then you can get 12V 10A at the output?