Anyone used a DC to DC converter to run lights from battery?

[doublestout]

Hi, Just ordered a DC to DC converter from E Bay. The lights that I have with the bike are ok but I want to run my normal lights. I have a single led cree t6 which is a brilliant light. Plan is to replace my 36v front and rear lights with the cree light and a magicshine rear light. My commute is mainly roads - some with no street lights and I need something that works.

Would like to know if antone has tried this and what success they have had.

Current set up is Solar Storm X2 - on helmet and bars. T6 light where my standard 10 lumen light should be on the bridge of the forks. Rear lights RSP 1/2 watt rack light which was much better than the standard 36 v light. In addition 2 x 1 watt lights from planet x. and one on the back of the helmet.

Yeah I know, overkill but drivers can see me!

 

[Alan Quay]

Yup, I have three bikes, all running with DC-DC converters. On my main bike, I keep them on all the time, so they have done about 1300 miles.

You need to ensure that your converters have 50v input capacitors, or they will blow. Also, I keep the load less than 1a at 12v.

The ones I used last time. They are rated at 35v input, but mine are happy to run at 42v. Only a couple of quid delivered.

http://pages.ebay.com/link/?nav=item.view&id=131023752686

I put mine into an Altoids tin, with a small switch on fuse in the feed side.

 

[doublestout]

Thanks Mike.

My cree light is around 8v and as far as I can see for the moment they run at around 1a. Been a long while since I looked at anything like this so having to read up. The converter runs between 1 and 3 amps. No idea what the input capacitors are, but can have a go and see how it gets on.

Thanks for the link and extra information. Saved one of the converters in my watch list in case I need one. Paid around the same price for mine.

Just out of interest what lights fo you use?

 

[Alan Quay]

You only need a fuse if things go wrong ;-)

Believe it or not, I make my own from pipe fittings and domestic LED spotlight bulbs.

They are extremely bright. The latest ones are a bit too bright. They can dazzle from 100 yards in daylight.

Here's the link:

http://www.pedelecs.co.uk/forum/threads/cheap-homemade-led-lights.14152/ URL]

 

[doublestout]

Thanks for sharing. Magicshine rear light is £30 cheapest so think I may experiment.

 

[Alan Quay]

For a rear light, get some self adhesive LED strip, in red from eBay. Cut as many lengths as required, and connect up parallel (if 12v) or series (36v).

 

[patpatbut]

I have this from Paul

http://em3ev.com/store/index.php?route=product/product&path=41&product_id=90

Works well for my cree light (36v > 8.4v)

Pat

 

[cwah]

I've been using this converter on number of led (including magicshine) and never had any issue:
http://www.ebay.co.uk/itm/DC-24V-36V-48V-60V-64V-72V-To-12V-10A-Converter-For-Electric-Storage-Battery-/400589244381?pt=UK_Home_Garden_PowerTools_SM&hash=item5d44fac7dd

 

[doublestout]

Looks like there are plenty of options out there. When first considering this I knew someone would have 'tinkered' however its starting to look like quite a few peope are experimenting.

Plan. on delivery of my converter is to run my cree t6 on 8v and around 1A. That shouldn't be too much of a problem. As nights and mornings are now getting lighter I have time to play around with different ideas. My rack light is an RSP 1/2 watt and is fairly effective (price £5). Works from 2x aa. May end up running 2 of these on the back or make something for myself at a later date which runs at 12v.

Too tempting not to give Mike's home brew LED a try.

 

[tongxinpete]

On my TGA the controller aluminum case & the metal batt frame & whole bike is earthed to 24V batt neg, the lights (12V) use frame earthing to run, & + are tapped off one batt @ 12V. This I think has led to unequal discharges & led to the failure of one batt. I am worried that the common earth system cannot be used for the output of a dc-dc converter? (as the input & output would share the same neg frame earth) I could modify the lights to remove frame earthing, I could also series the at present parallel bulbs (not then needing the converter) but this means if either bulb fails I have no lights. Do I need to isolate the lighting neg from the 24V frame neg to run the converter? At present I have disconnected the lights. It would be quite difficult to isolate the controller case from the mainframe, so i am leaving this part as it is.ie the bike metal will always be 24V neg, I am new to this bike, just renewed the SLA's to get it going.

 

[Alan Quay]

I have run dc-dc converters from a common 0v before, and continue to do so. In fact, just out of principle, I normally tie all the 0v bits together.

I agree that powering 12v stuff from a single battery is not ideal, although I'm not sure how much of a problem it is in practice, especially with a small drain like a few LED's.

I did toy with the idea of swapping my 12v stuff from one battery to the other (or the other, when I had SLA's I ran at 36v) but that would require you to have a seperate 0v line on the 12v circuit, and is a recipe for disaster.

 

[103Alex1]

One of these tapped off your battery +ve before the controller, common grounded to 0V. Output up to 3A at stepped down voltage, so can run easily 2 x 1-LED Cree T6 front lights and a 3W rear light. Step it down from 36V to 9V to match battery packs normally used with magicshine clones for similat performance, though I reckon they have constant current chips on the light driver boards in any event.

Has a built-in heatsink and can easily be housed in a plastic project box without problems. Dead easy. Just google one with free shipping - LM2596HV

http://www.ebay.com/itm/4-5-60V-to-1-30V-LM2596HV-DC-DC-Voltage-Regulator-Power-/231061855323?pt=LH_DefaultDomain_0&hash=item35cc5c1c5b

 

[twinkle]

Personally , I would use a Radio control electric plane 3 s 1800 mah lipo and its correct charger rather than link to the main battery , This would give a 12 v ( 11.1 v ) supply and would power the lights for quite a while .
A 2s pack is 7.8 volts , The main reason for using a separate battery is that any additional lights will drain the all important Go juice from the main battery reducing the range , some of these power supplies use a lot more current as they are not designed to be efficient . Having played with add on lights on and off (pun included ) for twenty or more years , well before e-bikes I have found it to be an easier option .( obviously the safety requirements on charging should be met ).
Being a car driver as well as a bikie , Dazzling motorist by pooly adjusted or badly designed lights is not a good idea and Its NOT a case of being seen, it is down right stupid , you might have been seen but that poor motorist could hit another cyclist as his /her eyes readjust after the incident ..
********* FOOD FOR THOUGHT .*********

Just another option and only my tu pennyworth .

regards emma

 

[103Alex1]

Hmmm ... the current drawn by a single CREE+rear light at a main 36V battery is tiny (less than 0.5A) and the effect on range / 'juice' over even 3 hours of night riding is likely to be negligible.

You won't dazzle motorists if your lights are properly adjusted.

 

[Alan Quay]

Hmmm ... the current drawn by a single CREE+rear light at a main 36V battery is tiny (less than 0.5A) and the effect on range / 'juice' over even 3 hours of night riding is likely to be negligable.

Agreed. Modern dc-dc connverters are 80 to 90% efficient. LEDs are also extremely efficient.

On my setup, I reckon I'm drawing about 400ma on the 36v side. That means I could switch my lights on now, and they still be running as the England/Ireland game finishes on Saturday afternoon. Or to put it another way, 4% on a 2 hour ride.

 

[ace.paul]

Hi guys on my BATRIBIKE SPRINT i have a Solar Storm 5000 LM
brilliant bit of kit, great for blinding these impatient car drivers that despite the speed your going still cut you up.

My rear light is a Poundland rear light with two 1 Watt Luxen LED's in them - could have fitted 3 but involved getting up to get a Dremal

The back light is powered by a small old mobile phone battery, i keep meaning to sort it out and make 1 battery power both lights.

DC-DC converters can't quite see the point on a electric cycle, powering a 19V laptop from a car battery yes, but seperate battery is just as easy.

I have several old laptop batterys i used to make a battery back up for the solar storm, but that was as far as it got.

 

[103Alex1]

DC-DC converters can't quite see the point on a electric cycle, powering a 19V laptop from a car battery yes, but seperate battery is just as easy.

Saves charging the light battery and taking on/off bike (or forgetting to take it - something you can't do with the bike battery !). I'd much rather get on my e-bike and switch my lights on than faff about with multiple batteries. It's one thing I wish I'd done with the Kalkhoff rather than still strapping on light battery packs, but never got round to it. Nights getting lighter now though, and can't be bothered to muck about with the bike battery wiring as it's internally frame-routed and a step-through - so going to wind up looking clearly like a "mod".

 

[twinkle]

Hmmm ... the current drawn by a single CREE+rear light at a main 36V battery is tiny (less than 0.5A) and the effect on range / 'juice' over even 3 hours of night riding is likely to be negligible.

You won't dazzle motorists if your lights are properly adjusted.

Even with 504 WH of Lithium capacity I still have to row the trike home some days , that extra 1/2 an amp would be the last straw that breaks the camels back , Just because it works for you does not mean it works for others .


You HIT THE NAIL right on the head there " properly adjusted "
I wonder just how many bikers ACTUALLY set their lights ups corrctly and then prop the bike up and LOOK at the lights just to check thet they dont dazzle motorists

AGAIN food for thought

regards emma

2 ,3 4 5 and 6 wheel road user . !!!!!!!!!!!