Do you think it's using a DC-DC converter inside or is the light really running at that high voltage? Seems like a great way to reduce wiring, by tapping the CA!Wiring the Power
These bike lights need to tap into your electric bicycle battery pack for power. Since most ebike systems don't have a convenient access point for running auxiliary devices from the main battery, a small amount of custom wiring is required to hook the light into the system. We suggest any one of the following techniques:
Anderson Powerpole Tap: Use a small screwdriver to remove the pins from the Anderson powerpole battery connector on your motor controller. Then solder thin wire leads to both the positive and negative leads pins, and press them back into the housing. You'll now have a tidy tap point into the motor controller power bus which can be connected to the bike light.
Inline Powerpole Splicer: Another approach is to make a device similar to the Cycle Analyst shunt which is terminated with Anderson powerpoles on either side. This then plugs in between the battery and the motor controller, and unlike option (A) it can be easily removed from the system if necessary.
Cycle Analyst Tap: If your system already has a Cycle Analyst, then there is already the full battery power available at the handlebars and you can tap into this rather than running an additional wire down the bike. This approach will require opening the Cycle Analyst box, drilling a hole in the casing to feed the wire out, and soldering the wire to the battery power leads which you'll find connected to the pads labelled V+ and G.
Battery Charge Port: One possible location to access power from the battery pack without additional wiring is through the charging port for the battery. If you attach a 3-pin male XLR connector to the leads of the bike light, then this can plug into the charge connector on the battery pack for powering the lights up while you are riding.
There are certainly other possible ways of accessing the battery voltage, such as a tap inside the motor controller, wiring an additional auxiliary power line directly to the terminals of the battery pack, or partially stripping the insulation off the battery leads and splicing in this way. Just note that in any case, the light is supplied with bare wires on the end, and you'll need to do a bit of work to hook it up.
No doubt, just thought it interesting... and wondered:nicobie wrote:I think Justin was talking about taping the full battery voltage at the CA plug.
Great idea! A resistor!deswong wrote:In your case I would use an appropriate resistor to drop the voltage from 80/90v to say 40v, then use one of these DC to DC converters to then further drop it down to what you require.
Cool! A DC-DC power supply? Or an AC adapter? What would happen if I plugged an AC cell phone charger into the battery pack supply? When hooked up to AC, it only outputs ~350mah @ 5V(?) tho...docnjoj wrote:I use a 2 stage D/C converter. I use a laptop power supply to lower the voltage to around 19V...
Hey Grinder,grindz145 wrote:Pulling a tap off of one of the cells isn't a terrible setup with a balancing charger.
Lets see... 80V in, 40V out -> 40V drop. DC-DC drops 40V to 12V... call it 4:1 LED draws 1 amp, DC-DC in is 0.25A P=I*I*R = 0.25*0.25*1000 = 60 watts. Bring mashmallows!GCinDC wrote:I've got a spare 1k 5W. I'll see what that does to 80V..
Awesome news. Is there any way to tell the difference?texaspyro wrote:I would try a switching type wall wart (not a transformer type) or laptop supply. 120V in to 12V out They usually run just fine on DC in.
A DC-DC converter converts power in to power out (minus a gratuity to the friction gods). If you need 12V at 1A (12 watts) out, you need 12 watts in. 12W/40V is about .30 amps in. Actual conversion efficiency may be 80-90%, so figure .35A inGCinDC wrote:LOL. Well, now that it's winter, maybe I can kill two birds with one stone and make handlebar grip-warmers...
I love the math. Thank you. But I lost you at "DC-DC in is 0.25A". How do you figure? I get that it's not gonna work, but am still curious how you figure .25A if the light pulls 1A (actually 1.5A on high)... <scratches head>
I tried an old Iomega Zip Drive power supply that was 12V 1A out. When I connected the DC power (~60V) to the AC plug pins it let the magic smoke out. Any advise on how to avoid this result? I think if I had tapped it past the bridge rectifier, it may have been ok. Problem is, how do I figure out which component is the BR? Thanks!texaspyro wrote: I would try a switching type wall wart (not a transformer type) or laptop supply. 120V in to 12V out They usually run just fine on DC in. Most will run on the lower input voltage, particularly if you use one rated for more output current than you will be drawing.
Not really Greg, I imagine that's because of some other configuration issue with the pack, or just dumb luck. The current going through the pack is the same so they really aught to be the same given equal impedance. It's possible that the top and bottom connections are a little worse so you end up with a bit more voltage drop.GCinDC wrote:Hey Grinder,grindz145 wrote:Pulling a tap off of one of the cells isn't a terrible setup with a balancing charger.
Yes, I'd feel less hesitant about this, except that I'll be moving off the balance charger soon, to (blindly) bulk charge @ 83.6V (ping + laptop).
So am wary of tapping part of the pack now, since i won't get to see how far out of balance they'll get...
This is OT now, but your comment re capacity/impedance reminds me - and since you're a battery guy - is it typical for a pack's end cells to wear harder than middle cells?
If anything, the bridge rectifier will provide some protection against reverse voltage on the input. It won't prevent the circuit from working. The Zip zupply may have been transformer based, not a switcher. I seem to remember that mine was.number1cruncher wrote:I tried an old Iomega Zip Drive power supply that was 12V 1A out. When I connected the DC power (~60V) to the AC plug pins it let the magic smoke out. Any advise on how to avoid this result? I think if I had tapped it past the bridge rectifier, it may have been ok. Problem is, how do I figure out which component is the BR? Thanks!
I doubt it, but it is possible that if the rectifier was not rated for the current draw it took at the lower input voltage, it could've smoked that.number1cruncher wrote:I tried an old Iomega Zip Drive power supply that was 12V 1A out. When I connected the DC power (~60V) to the AC plug pins it let the magic smoke out. Any advise on how to avoid this result? I think if I had tapped it past the bridge rectifier, it may have been ok.
Most BRs have little tilde symbols ~ on the two AC pins, and a + and - on the DC pins. You'd wire the DC input to those two pins, just as they're marked, if you want to bypass it. It might not be a BR, though, might be separate diodes, usually a cluster of four, sometimes only a half-wave as just a pair of diodes.Problem is, how do I figure out which component is the BR? Thanks!