ovrrdrive

After reading the forums for a few weeks I decided it was time to have a go at a DIY light.

I'm a little broke atm and saving for a real roadbike, so I wanted to go as cheaply as possible. In considering battery options, I was originally thinking lead acid like in a $20 motorcycle or lawn mower battery, but then I started looking around the house instead at what I had here.

First I considered 2 6V lantern batteries but nixed that because I couldn't recharge them. Next was a 7.2V LI battery that I have a good charger for, but that wasn't really bright enough with the 12V light I had.

Then I looked at my rechargeable drill. 14.4V, with a quick charger. I checked it on the poles and it was putting out 15.59V so it seemed like a perfect - no buck - solution for me. The only problem is hooking to it without making a permanent connection like soldering. I settled on some insulated alligator clips for now until I can figure out a better solution. I may end up looking for the same drill on ebay and cutting the entire bottom off and mounting it to the bike. This would allow me to solder all the connections and very quickly ans easily remove and reattach the battery to the bike. If runtime is acceptable (will find out in the morning) I'll consider doing that but if its dead in 10 minutes I'll just buy me another battery solution.

As for the MR16, I found a 1.5" PVC inline coupler that it fit almost perfectly in. I ground the inside lip a little to make the light fit flush, and then set it in with a few drops of hot glue, then sealed the entire seam with quick set epoxy. I mounted it to the bike by bending down the front reflector holder and removing the reflector, and mounting it with a few bolts and washers. To lock the nuts on I just slightly bent the bolts over. This way if I need to I can still remove them and just put it back with new ones.

The battery is temporarily just stuck on where it fit snugly, and strapped on with a velcro strap I found in the garage.

Light is simply amazing. I can't wait to get out there in the morning and see what it will do. For the time being, I'm leaving all of the other lights on the bike in case the battery runs out or something blows up, but hopefully eventually I can remove them. Time will tell...

All in all, I spent $5 on the bulb at Lowes and maybe another $5 on connectors and what not. I did try to find a way to dim it a little with no success. A rheostat from Radio Shack worked great, but being rated at only 3 watts it started smoking in under 30 seconds. I'm going to try a dimmer switch from a camper supply store when I get a chance. I'll update the thread as I make progress.

Here's the pics...

First, a flash pic of the garage door for reference:



Next, the $13 Schwinn 3 LED light I bought that's actually pretty bright:



And the $15 Bell Xenon light. This is what I have been riding with. Sucks doesn't it?



And now with the MR16 turned on...



The battery pack...



And pics of the PVC coupler with the bulb in it:




I'm going to keep working on the enclosure and seal up the back and paint it all. I just got it to here and threw it on the bike to test the light output. I'll probably put the battery in a tailbag or something eventually if I don't find another more secure way to mount it. Like I said, I'll find out how this all does in the morning and I'm sure I'll be making adjustments.

Ideas? Comments? Suggestions?

sknhgy 

I like the simplicity of your light. Please, keep up the effort. Let's see what you come up with.

Chris_F

Looks like you have the light enclosed in PVC. If that overheats and melts you can always go with a metal pipe. I'm sure they have plenty at the hardware store. Like the cordless drill battery idea. Very cool. I don't know how efficient a dimmer would be though. Wouldn't you just end up dumping extra energy in to the dimmer? I don't know how the professionally designed lights do their dimming. PWM electronics perhaps?

ovrrdrive

I think you're right about that and that was one of my concerns... I think that's why the rheostat got so hot, because it was absorbing the energy instead of the bulb getting it. I'll have to do some more research.

ovrrdrive

Light this morning was absolutely amazing. I saw more rabbits than I think I've ever seen, and instead of waiting until I was right on top of them to run they ran into the weeds well in front of me. There is a definite safety factor with brighter light on the bike. Me likey.

My drill is a few years old, and one battery has gotten really weak. For purposes of testing, I of course used the weaker battery.

Light was bright for about 20 minutes then dimmed suddenly so I turned the light off. It was a bit colder than I expected it to be though so I was on my way home anyway. I'm going to charge the good battery and use it tomorrow morning and hopefully I can get a few days out of it before it will need charging back up. To give you an idea of the condition of the battery I used this morning, I put it on the charger when i got back home and before I got out of the shower it was done. It charged back up in less than 20 minutes.

All in all I'd say it is a success. Even if the best light I ever got out of it was the 20 minutes it would be worth it but I'm certain the better battery will work better. Plus, it opens up a whole new source for light batteries. I bet you can get good quality 14V drills for a steal...

I'll update tomorrow on the other battery's performance.

edit. And btw, with ambient temps around 43F heat wasn't an issue with the PVC. It may have been with the battery though, I'm not sure what temp they like to be at. Temp was an issue with the duration of the ride though...

Juha

Safety factor? What kind of rabbits are we talking about here, thuggish pack-hunting carnivores?!

J/K. Nice light. One additional plus in your setup is, there is a good selection of 12V MR bulbs with a myriad of wattage, beam angle and beam color combinations available. They're not too pricey either. If need be, it will be easy to fine-tune your light.

--J

ccd rider

"You know how that rabbit feels
Going under your speeding wheels"

- Neil Peart

fordfasterr

Sure does, you can buy the battery packs separately for even less $$.

Looks great and Good luck !

zagnut

I posted an inquiry here about using tool batteries and received no replies. I did learn on my own though, that many (not all) can be opened up and you can see the pack inside. I purchased a couple of Lowes Task Force 12 v that they were closing out for $3.50 each but after opening them up, I found that the NiCads were only rated at 2300mah (IIRC). Most of those tool batteries have regular phillips head or sometimes allen head screws holding them together. I also wonder why most tool chargers are fast chargers i.e. under 2 hrs and most under 1 hr. Does that effect performance? or is it just the type of battery that they use?

Zagnut

ovrrdrive

That's exactly what I've seen in a quick search of Amazon and Ebay. Most of them are nicad and in the 1200-2200 mah range. There are a few good nimh 3300 ma batteries out there from companies liek Makita but they are running around $100 which is way too high. The one I'm using is nicad but I couldn't find a rating on it. If it can get me through an entire ride without needing recharging it will work for me for a while, but I see an $85 5k mah water bottle battery in my near future anyway.

This was more an experiment and to get a light right now from what I had laying around the house so I could see better. I definitely don't see it as a permanent solution...

Btw, It makes sense that they use the quick chargers for drills so you don't have to wait as long between charges. If it's your maoney maker ideally you need a charger that charges the spare battery as fast as you drain the one in the drill so you don't have to wait. From what I understand the quick charger isn't as good for the battery and doesn't charge it up as fully as a trickle charge does.


Man, you guys don't cut any slack around here do you.

cyccommute 

Heed ye the words of Tim the Enchanter

"Follow. But. Follow only if ye be men of valour, for the entrance to this cave is guarded by a creature so foul, so cruel that no man yet has fought with it and lived. Bones of full fifty men lie strewn about its lair. So, brave knights, if you do doubt your courage or your strength, come no further, for death awaits you all with nasty, big, pointy teeth."

cyccommute 

How about $18 3.3 Ah batteries? Two of them in parallel produce 6.6 Ah...theoretically Two in series produce 3.3 Ah at 14.4V. Get 'em here.

fatbat

If you've got a good charger for the 7.2V battery, then two 7.2V batteries in series=14.4V. might be easier to work with than drill batteries.

Chris_F

Why not just wire a dozen or so standard NiMh batteries up in series? A dozen or so AA size would cost around $50 or so, right? And hold maybe 24,000 mAh. Step down to AAAs and it'll cost about $25 for 8,500 mAh. DigiKey sells 'em with solderable end tabs if you're not inclined to get a spring loaded holder, and they sell 'em in packs (like the ones linked in cyccomute's post). Digikey also sells Lithium batteries that'll put out 6 volts for about $6 with 1400 mAh, two would be 12V at 2800 mAh.

Most interesting I think are the sealed Lead Acid Panisonic batteries they sell (page 2120 of their current catalogue). They come in 12 volt versions with spade lugs weighing from 1.3 pounds (4"x2"x2") at 1,300 mAh at $25 to a 5.5 lb 6x3x4 inch battery at 7,200 mAh at $28. They get bigger and badder but that's probably the limit on a bike I'd think (unless you want a 26 pound 33,000mAh monster. Down side is you'd have to trickle charge 'em as they won't like a fast charge very much. I use one of these on my home burgler alarm and it trickle charges continually off the house power.

ovrrdrive

12 AA's would yield 24,000 mah?

Are you sure about that?

The biggest regular sized pack I saw on the pages was about 7200 mah and they wanted several hundred bucks for it. And I think that pack used C size or D size cells.

I think my plan is just going to be to use the drill batteries for a few more weeks and then just buy a water bottle 5000 mAh battery and charger. It's only $85 and should power the light for a few days between charges for my entire ride. Eventually I'm probably going the LED route anyway and this would power that for a week or more.

https://www.batteryspace.com/index.as...OD&ProdID=2462


The sweet spot on the price there appears to be the Roomba batteries at $35 for 14.4V nimh 3300 mAh but it doesnt have a charger. By the time I get a charger and plugs, I can just get the one in the bottle with a higher output and a neater package.

Chris_F

No. DigiKey's spec sheet is listing a capacity of 1500-2200 mAh per AA battery (depending on how much you want to spend). I'd assume this adds when used in a pack so 12x2000 or so is 24,000. Or is my math off? (that would be embarrassing).

I can't vouch for the accuracy of DigiKey's spec sheet.

Now that I think about it, they don't add if wired in series (to get the voltage), do they? DOH!

ovrrdrive

Yeah, I think that's it. If you series them you get higher voltage but the same Mah. If you parallel them you get same voltage but higher mAh. You could take two seperate groups of 12 batteries wired to produce 14.4V and parallel it with another battery wired to produce 14.4V you get 14.4V with the combined mAh.

Chris_F

Not only was I wrong there, but the lead acid batteries I mentioned... I'm not so sure they'd appreciate the vibration. They're sealed so they won't leak at least. Car batteries are lead acid so maybe they'd be okay. Perhaps worth a try (cheap amp-hrs for the money) but I'd have a backup handy just in case.

ovrrdrive

Another dilemma for using the drill battery surfaced this morning...

Using the good battery, I made it through the entire ride this morning without going dead which is good. However, now since the battery I'm using is a nicad I can't recharge it until its dead, and I don't know how much juice is left in it. I'm pretty sure I can't make it through another ride without a recharge, and I don't want to partially charge it.

I guess when I get home I'll put a fan on it and turn it on to see how long it lasts.

I'll probably pony up and get a real battery pack this weekend I guess.

cyccommute 

NiCd doesn't need to be 'dead' to recharge. You just need to have a cell voltage of around 1V per cell. You can do a partial recharge just don't do it all the time. Here's all you need to know about the care and feeding of batteries

ccd rider

"Where is it, behind the rabbit?"

"It IS the rabbit!!!"

cyccommute 

Sir Robin: You tit! I soiled my armor I was so scared!

ovrrdrive

You guys are off the chain...

The light ran for another 12 minutes before going pretty dim. I'll just have to make another lap in the morning to drain it all the way out.

Cyclaholic

The vibration on a bike are not a problem for sealed lead acid batteries, I've been using them for years. The up side is that they're relatively cheap, the down side is that they're heavy for their capacity compared to other technologies.

I used to run a 20w MR16 on a 7.2Ah, 12V SLA that weighed about 6 pounds. I used to run it pretty hard, about 90% DOD. I got about 600 cycles before it dropped about 30% of its capacity, which was better than the manufacturer's specs.

I'm now running my triple XR-E LED's on a 3.2Ah SLA that weighs 3 pounds. It lives a much easier life, rarely discharging deeper than about 50%. One big difference is that the LED's draw about 600ma where the MR16 used to draw around 1900ma.

Bikehead

You can use 1 1/2" Conduit ends, and one 1 1/2"
chafe ring,for the light. You can get full plans at
www.bike-recumbent.com. I made one and it has
done a good job, the last 6 months. Still trying
to figure a way to fashion a part to hold the bulb.
Would hate for it to pop out.
It's made of metal, and won't melt. But it's gets
hot enough, to burn you after a half hour run time.