Electronics, Lighting, & Gadgets - Total Geekiness

i mounted my battery out in the open, and it gets rained on some but has not seemed to matter, i built a bracket that mounts it in my water bottle holes

Sigh...

OPTRONICS!

http://www.optronicsinc.com/competition.htm

Why reinvent the wheel when these are so cheap? Look at the QH-8CC. They are small, look right at home on bike, handle a 50 lamp, are easy to fashion mounts for, and CHEAP, about $16 per PAIR. You can order directly from Optronics if you can't find them locally. 50W is more than most people want to carry battery for, so replace them with a 20 or 35W. They have slots for ventilation. I don't tape over them, but I do make a little "hood" with tape to keep rain from dripping straight in. This has worked for a couple of years, including some very rainy rides.
FWIW,
Raymond


The housings look really good. It's always a problem for us homebuilders to find a cheap suitable housing. The first two beam shots are good, they show how bright the 35W spot is. The third shot needs something to compare, like a car headlight.

Question for MR16s users. What bulbs and beam angles are you using?

I am currently running a 20W 12 degree spot and a 10W narrow flood (I guess a 24 degree). I find the 10W narrow flood useless and have it really as a back up light. I just placed an order for 3 35W Solux bulbs at 10, 17, and 24 degrees to try out. If I like the Solux bulbs I will need to upgrade the battery to a 10 or 12ah to have enough run time. If I don't like the Solux bulbs that much I will probably end up ordering the Phillips bulbs and keep on using my current 5ah battery.

Do we have anyone carrying large (i.e. 10 or 12ah) batteries?

PS: I have by now recognized that by the time I am done with my lights I will have spent a ton of money and time on my lights. Well as a hobby it is not that expensive...

Btw, forgot to mention that I transformed a Minoura bottle cage clamp into a helmet mount. What you need to do is replace the metal ring that travels inside the clamp with a Velkro strip and use a rubber pad or ring (I use a garden hose rubber ring) between the clamp and helmet to compensate for the helmet surface irregularities. Once you are ready to mount it you close the Velkro and use the clamp's bolt to tighten it firmly. It is rock solid and looks good. I can post pics if this does not make sense in writing.

I have also ordered my second set of Optronics light, now the metal ones. I think the vents on the plastic ones may be an issue under heavy rain and don't want a short at night, under the rain, and 10 miles from home so the plastic ones will be gone and replaced my the metal Optronics this weekend.

jz19 -- I have the chrome metal lights from Optronics (they gave my first bike a kind of retro look) and I love them. Never had a problem with rain in them although you need to make sure the front ring that holds the bulb in is firmly attached. I had mine pop out one night and had to search the side of a busy street to find it.

I also use a similar 10w and a 20w MR-16 combo on my homebuilt light setup. The 10w does not do a whole lot in streetlights, but it is bright enough to be seen. On the dark trail I ride, the 10w is reasonable at 12-13 mph. Faster than that and I switch to the 20w. The 20w is fabulous although it can be annoying to oncoming cyclists so I try to watch for approaching lights and switch down when I see someone else. I find a 5AH both plenty heavy and plenty of juice for 2-1/2 hours or more of riding without recharging.

Question for MR16s users. What bulbs and beam angles are you using?

I am currently running a 20W 12 degree spot and a 10W narrow flood (I guess a 24 degree). I find the 10W narrow flood useless and have it really as a back up light.

Do we have anyone carrying large (i.e. 10 or 12ah) batteries?


I am using a 20w 36 degree flood. it throws out lots of light to be seen by, but is a bit more diffused than I would like. do you think the 12 deg spot is sufficient on its own without more side lighting? I am thinking of doing a 20w philips and will do a 24 degree unless someone convinces me the spot will do the trick.

I have a 6ah sla battery, so don't plan to boost up to the 35w bulbs.

I'll check the spread on my bulbs, but I find the 20w spot easily lights up the whole bike trail and its shoulder area. I think it is more visible to cars from the side because it is so much brighter it can contend with headlights. I'll check to see what degree spread I have on mine and post later tonight.

Question for MR16s users. What bulbs and beam angles are you using?
I use a pair of xenon 10w bulbs of unknown angle -- from http://www.sailboatstuff.com/lt_G4_MR11_MR16.html. They do a good job.

I use a pair of xenon 10w bulbs of unknown angle -- from http://www.sailboatstuff.com/lt_G4_MR11_MR16.html. They do a good job.

DCCommuter, how do they compare to halogen bulbs?

DCCommuter, how do they compare to halogen bulbs?
It's hard to say because I don't have any 10W halogens. One is less bright than a 20W halogen, but not by much. Two together are brighter than a 20W halogen. Some of that may be due to the fact that the reflector area is doubled with two bulbs.

Awesome! WOW!


Btw, forgot to mention that I transformed a Minoura bottle cage clamp into a helmet mount. What you need to do is replace the metal ring that travels inside the clamp with a Velkro strip and use a rubber pad or ring (I use a garden hose rubber ring) between the clamp and helmet to compensate for the helmet surface irregularities. Once you are ready to mount it you close the Velkro and use the clamp's bolt to tighten it firmly. It is rock solid and looks good. I can post pics if this does not make sense in writing.

Just a review on the battery I bought for my geek light. It is model CHUN-100DC02 from that great battery store BatterySpace.com.

I purchased a Laptop NiMH Universal External Battery 12V 4500mAh and Universal Smart fast charger from BatterySpace.com. It is made of 10 c-cells matched pieces. It is quite large and heavy and weighs about 1.5 pounds. It is small when compared to a SLA battery of equal voltage and amperage.
The battery comes double PVC shrink wrapped for water resistance in a nice neat package. The cord coming out of the battery is quite long and should accommodate most applications although it is thin.
.
It comes with a set of detachable universal connectors with 5 plugs that will fit to most DC rated devices. These connectors look well made.
One multi voltage smart NiMH /Li-Ion battery charger is included for safely charging. Auto cut off switches the charger to trickle charge power when battery fully charged. Just plug it in and leave it. It is not clear from the instructions what charging level I am supposed to use. The sheet of printed instructions that came with the unit are poor. Also, there are no instructions printed on the charger itself. It would be nice if the key instructions and a code explaining what the colors of the LED mean were printed on the back of the charger. I have seen this on other models and it is very helpful.
My other observation and suggestion for charger is the fabrication of the connector and the end of the cord. This connector is used to connect the battery to the charger and to connect the battery to the connectors supplied in the kit the connector is made up of two pins that stick out from the end of a plastic rubber like wire about an eighth of an inch These pins are exposed and are of slightly different thickness. The difference in diameter makes it easier to insert into the female connector that is on the battery. exposed connector. The small nature of the pins and the diameter of the connecter make it a little difficult to use. The exposed pins are thin and split down the middle making it easy to break them off. Also, the cord if thin. The point where the cord enters the charger is well supported by a plastic nub. Heavy rubber would be better as the plastic could break if the charger is dropped.

The power cord is beefy and the connection to the charger is snug but not too tight. The cord coming from the charger to the battery is long enough for most applications. There is an inline fuse. The plastic fuse holder is made of hard plastic and although it is not something that is opened often, these types of fuse holders are know to fail; that is the little nubs that hold the two ends together snap off. The kit comes with three extra fuses..
The battery did not come fully charged from Batteryspace.com. It took about 2 hours to charge it.

I am using this battery for my homemade for Halogen bike headlight. The burning time is about 4hrs.

Question for MR16s users. What bulbs and beam angles are you using?

I originally thought tight beams were the way to go, 8-12 degree. They do throw a lot of light out front. I found, though, that the edge of the road was completely dark. I always like to be able to see a few feet off the road in case I need to bail. I am now using 24 degree which I like much better. When I need to replace I will probably try 36. With 35W or 35W equivalent lamps there is plenty of light out front.

Right now I am only using a 5 AH battery, but I plan to set up a 12 or so at some point in order to feel comfortable that I can run a 35 or even 50W Solux lamp for well over 2 hours.

Do we have anyone carrying large (i.e. 10 or 12ah) batteries?

PS: I have by now recognized that by the time I am done with my lights I will have spent a ton of money and time on my lights. Well as a hobby it is not that expensive...I just built a 10AH 13.2v battery-pack for my HID project. Ended up about $70 for 11 of these nimh D-cells:

http://lib.store.yahoo.net/lib/zbattery/nmh9500t.jpg (http://www.zbattery.com/zbattery/nmh9500t.html)

Wired them up in series in two rows:

http://www.gururacing.com/cycling/bigbatterypack.jpg (http://www.zbattery.com/zbattery/nmh9500t.html)

Just about 8" long, so I can stuff it into a 24-oz water-bottle if I wanted. However, I think I'm just going to wrap it in heat-shrink tubing and zip-tie it under my downtube near the BB.

Do you all run fuses on your homemade setups? I'd like to not run a fuse just because it'd make my wiring organization more difficult. Plus I'd have to change fuses if I wanted to switch back and forth between different bulbs. Do you guys think runnin' w/o a fuse is a big deal?

No fuses on mine but each circuits has a separate toggle switch.

Just use an in-line fuse. No need to change fuses, they're just for short-circuits, so a 5-amp fuse will be fine.

I just built a 10AH 13.2v battery-pack for my HID project. Ended up about $70 for 11 of these nimh D-cells:

http://lib.store.yahoo.net/lib/zbattery/nmh9500t.jpg (http://www.zbattery.com/zbattery/nmh9500t.html)

Wired them up in series in two rows:

http://www.gururacing.com/cycling/bigbatterypack.jpg (http://www.zbattery.com/zbattery/nmh9500t.html)

Just about 8" long, so I can stuff it into a 24-oz water-bottle if I wanted. However, I think I'm just going to wrap it in heat-shrink tubing and zip-tie it under my downtube near the BB.

Nice setup Dannol. Don't know what your roads are like but, because of the weight, you may need to double wrap 'em. Also the diagram looks like its missing a negative lead on row2 (leftmost cell)

Do you all run fuses on your homemade setups? I'd like to not run a fuse just because it'd make my wiring organization more difficult. Plus I'd have to change fuses if I wanted to switch back and forth between different bulbs. Do you guys think runnin' w/o a fuse is a big deal?

I do. It only costs $3 to add one and you only need to solder one additional connection so it is really not a big deal to add one. I have run a 10amp one with anything between 10W and 70W without problems so don't think that you need to change fuses after changing bulbs.

I do. It only costs $3 to add one and you only need to solder one additional connection so it is really not a big deal to add one. I have run a 10amp one with anything between 10W and 70W without problems so don't think that you need to change fuses after changing bulbs.


When choosing a fuse...if I go with the 5amp mini glass (5x20mm) fuse....what rating do I want since we're running 12VDC; 125VAC or 250VAC?

Nice setup Dannol. Don't know what your roads are like but, because of the weight, you may need to double wrap 'em. Also the diagram looks like its missing a negative lead on row2 (leftmost cell)Yeah, I was thinking about throwing in an old section of inner tube inside the shrink-wrap so that there's some padding between the battery and frame. Maybe some foam might work too. Or I might just strap a bottle-cage under my downtube in that location so that I can remove the battery easily... we'll see...

I think the battery's wired correctly. The left-most cell on 2nd row connects its +positive end to the -negative of the cell above. Then its -negative end goes to the +positive terminal of the cell to its right. All the cells are in series with the only free terminals being at the end of the series..

ok... i've been reading this thread for awhile now and i decided to make my own lighting system. i'm almost done and i've got some questions.

1st: i've gone through two different lenses(they both melted due to testing without a fan) and i'm on my third lense... the third being actual glass. it seems to be working great.... but, i would like to drill a couple of tiny holes in it for ventilation.. is this possible? side note: it will be rare that i actually ride in the rain. sprinkle, yes.. but no heavy rain.

2nd: i've used the same bulb(MR11 12v 20w without the lense cover) through all of the testing... after the first lense melting, i noticed that the base of the bulb that is supposed to be white, is half gone. now, at this point the white substance is almost completely gone AND the very tip of the bulb is turning a black/purple color. side note: the tip of the actual bulb is not touching the glass. Does the white substance relate to the life of the bulb or is there another factor/problem i'm missing??

3rd: the testing i've done has been in my workshop at 65- 80 degrees and i'll be riding in 35-70 degrees. and a wind factor will come into play while riding. should i not worry about the light bulb/lense overheating b/c i'm only testing it at a stand still?

light unit info: i'm using a mag light, yes... the big one. I cut 2 inches off the end and connected it to the bulky bulb end. that way, i can have access to it in three ways(1.the end screws off(where the batteries would normally slide in), 2.i can simply un-attach it from the bulb holding body, and 3. I can simply unscrew the bulb end) it's actually pretty cool. i'll have to take pictures of it.

battery system: i'm using a 5AH battery from radio shack.

options: i'm thinking about getting an MR16 bulb with the lense cover and trying it out for fit. the lense opening on the mag light is very close to 2 inches. so, i could try that if the MR16 runs cooler.... I have no idea.


any help would certainly be appreciated,

thanks,
Rich :D

Wheels4, why don't you just buy the MR11 bulbs with the lens on them?

http://www.buylighting.com/subcat.asp?catid=185

I have been reading the posts here and didn't believe that there were that many others who build bike lights. I use 12volt halogen bulbs for the front and a Whelen LED visor squad car light on the rear. The rear light is amber/red. People at work tell me they can see me over a mile away with no problems and they sometimes think its a squad car or wrecker. Some have even said, that if you ever get hit, I will testify in court that the person must have been blind not to see you. I run this with my 14.4 volt dewalt cordless drill battery.

jbone, i would... but, that would leave a gap in the opening for rain. i'm still in the testing phase... so, i'm going to try an MR16 to see if it will fit.

thanks for the website though.

Rich

Wheels4,

A MagLight head is PERFECTLY sized for an MR16 bulb. I am working with a covered bulb (GE edison 20W, 15o beam angle, also available as 40o), so as not to have a melted plastic cover; it is necessary to have a bit of spacer between the front screw-on ring and the bulb to prevent rattling.

How have you mounted the light?

austex, if you pm me your email addy... i'll email you pics of it with details. it's hard to explain without the pics.

but, i can tell you it is mounted with a quick release and that part of it works great.

Longtime rider, but new to these forums, and what a great thread! I've learned a lot already Could you guys critique my planned build?

I'm currently running a TurboCat S25headlight (10W+15W MR11s at 6V) plus the usual assortment of blinkies, LED headlamps, etc., but would like to upgrade to a homebrew system. Having entirely rewired my previous home, I'm quite comfortable working with electrical stuff, though I still definitely want to keep the system as simple as possible while still getting the functionality I'm looking for. After reading the Starlight 78 page, I'm thinking of putting together a 12V system with the following components:

- 20W MR16 high beam (which would be on most of the time), using the Optronics holders. In a living room test, an el-cheapo GE 20W MR16 (that doesn't seem that well made) noticeably outshines my current 25W system, and I expect the Philips energy saver 20W to be substantially brighter.
- Two Night-Sun Xenon strobes, amber front and red rear. 12V version, since they go through batteries pretty fast.
- Luxeon III low beam. Still working on how to make this work, but I have a Princeton Apex headlamp using the same emitter and I'm impressed with the output for situations where I don't need a ton of light.
- NiMH Battery pack in the 4000-4500 mAh range. Although it would be tempting to over-volt to bump up the output of the high beam, I'm thinking of sticking with 12V because a lot of the12V-ready LED products I've seen look like they wouldn't be able to handle the extra voltage.

Looks like with everything on, this system should draw just a hair over 2 amps from the battery, for a theoretical burn time of nearly 2 hours, though I realize actual burn time may be a bit less. My evening commute is only an hour, but I've heard NiMH batteries don't like being drained much harder than that, and if I push them harder I might not end up running my lights optimally. So it seems like a good idea to have a little "extra" battery capacity.

Also, here's an interesting question. After reading about people hooking up horns, cellphone chargers and other 12V car-like accessories to their light batteries, I got to thinking about cars' electrical systems, which hook the negative terminal of the battery to the frame, requiring only 1 wire to be run to each (grounded) component.

So why not do the same thing on a bike? It would be really elegant to run a single wire to each component, with each item's other pole firmly grounded to the bike frame. Anyone tried this? Since my front lights would be attached to the handlebar, I'd be running about 2A of current through my expensive King headset. Would that damage it? Or would I be risking accelerated corrosion by running current through my (steel) frame?

Thoughts?

- Dan

I have been using my frame as ground for over 6 months and it seems to work fine. I really like the simplicity of just running the positive lead where you need it. After having a over-complicated setup last year, I have moved to the other end and tried to make mine as simple as possible. My power switch is located on my underseat bag which holds my battery, so I only have one wire running to my front light and one to my rear light setup. So far, it has not let me down. I have an aluminum frame, steel fork, aluminum seatpost and rear rack, and the ground seems to work fine through all of these components.

Alright, I'm pretty new to this stuff, but am looking for a cheap way to get started. I already have built my lighting system which basically includes a couple of 20w halogen bulbs. Would this battery be good enough to power my lights for a 2 hour/day commute?

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2142

Alright, I'm pretty new to this stuff, but am looking for a cheap way to get started. I already have built my lighting system which basically includes a couple of 20w halogen bulbs. Would this battery be good enough to power my lights for a 2 hour/day commute?

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2142
I would advise you to get a 5 AH SLA battery and recharge it when you get to work. It will support your 40W very well for an hour, but won't last 2 hours. If you want 2 hours straight run-time without recharging, you'll need at least a 7AH SLA battery.

The formula is basically this:

Watts = Volts X Amps or Amps = Watts / Volts

So for every hour ("Amp/hr") of battery power you need, divide the total watts you are using (40 watts) by the voltage (12.)

40 / 12 = 3.33 or 3.3 Amp/hr. So you would need at least a 3.3 AH battery for each hour of run-time you want.

BUT--

There is a problem. The smaller the battery, the less it can carry higher wattages. For example, a battery that supports 20W for an hour might not support 40W for half an hour; it might run for 20 - 25 minutes. So you have to use "overkill" when selecting an SLA battery for your needs.

40W / 12V = 3.3 AH
2 hours X 3.3 AH = 6.6 AH
"Overkill factor" -- minimum of 7 AH (or even more.)

Remember that SLA batteries, while cheap and reliable, don't like to be completely drained. It shortens their life. ALSO--always buy a fuse for safety reasons, even a 12V battery can start a fire. You can get details from your local battery store.

William, if you don't like the idea of such a large battery, and you must have 2 consecutive hours of run-time, you can put separate switches on each of your 20W lights. That way, you can use 20W most of the time, and use the second 20W as a "high-beam" for special needs. Even with a larger battery, two switches will allow you to conserve power as you need to.

Littlebigman, thanks for that formula... i needed it. i'm right on track.

20w with 5ah battery will give me my 2hr run time with no problems. heck, i might even add another 10w light just because i can. then i can switch between them like you suggested.

thanks again.

Remember that SLA batteries, while cheap and reliable, don't like to be completely drained. It shortens their life. ALSO--always buy a fuse for safety reasons, even a 12V battery can start a fire. You can get details from your local battery store.
Thanks for the information. I would be able to charge the battery at work, so I'd really only need about an hour (or less if I switch the lights seperately, as you mentioned) of 40W runtime. I'm sure there are better ways to make this work, but right now I'm really only looking for a cheap way for me to get setup. Once I get my feet wet and know a little more about what I'm doing, I would plan on buying different (more expensive and better) batteries.

Can this type (SLA) of battery be 'overcharged'? The last thing I want to have to worry about while I'm charging at work is whether or not I left it on the charger too long.

Thanks for all your help.
;)

Ok, so it looks as though SLA batteries can be overcharged. This can easily be solved by using a common timer...but how do you know how charged the battery really is? How can I tell how long to even set the timer for?

Yeah, I was thinking about throwing in an old section of inner tube inside the shrink-wrap so that there's some padding between the battery and frame. Maybe some foam might work too. Or I might just strap a bottle-cage under my downtube in that location so that I can remove the battery easily... we'll see...

I think the battery's wired correctly. The left-most cell on 2nd row connects its +positive end to the -negative of the cell above. Then its -negative end goes to the +positive terminal of the cell to its right. All the cells are in series with the only free terminals being at the end of the series..
How do you recharge this system? How often do you recharge it?

First off, thanks to some of the folks in this thread for so much great info and advice. This is one of the things that makes the Internet great.

I accidently bought a MR16 20w without the front glass. Can I run that on my bike in wet weather? Do you have any suggestions on a cover. I am using the Optronics driving lights housings.


Thanks

Kevin

Oh, and what can I do with the 55w bulbs that came with those lights? :)

Littlebigman, thanks for that formula... i needed it. i'm right on track.

20w with 5ah battery will give me my 2hr run time with no problems. heck, i might even add another 10w light just because i can. then i can switch between them like you suggested.

thanks again.

Unless you have a commute well over an hour replace I would suggest that you make that second bulb a 35W Solux. I like my Solux bulb, very nice white light.

I accidently bought a MR16 20w without the front glass. Can I run that on my bike in wet weather? Do you have any suggestions on a cover. I am using the Optronics driving lights housings.

:)

I would not try it. Just go and buy one with the lense. The Optronics housings work fine under the rain. I tested the black plastic one by leaving them under the rain for 90 minutes without problems. The metal ones should work fine too.

jz, my commute is one way... 22.5miles. it takes me between 1hr30min's and 1hr50min's. if i move up to a 7AH battery, i could go with more watts in the bulbs... but, for now i'll stick with the 20 and maybe add a 10watt in the mix.

thanks for the suggestion though.

by the way.... does anyone know what an H3 bulb is as far as wattage?? i've got some little driving lights that i was going to put on my mini-dune buggy but i'm not putting them on there.

thanks.

by the way.... does anyone know what an H3 bulb is as far as wattage?? i've got some little driving lights that i was going to put on my mini-dune buggy but i'm not putting them on there.



H3 comes in a variety of wattages, but it's mostly used for things like fog lights that are far more powerful than typical bike lights --55 and 100 are common wattages. I seem to recall seeing a 27-watt version, but that's the lowest.

How do you recharge this system? How often do you recharge it?I've got a 10w MR-11 light right now. Don't have a regular commute or anything, so I've been using for afternoon rides where I get caught up after sunset. Probably about 1-1.5 hours a day. I have put a female DC socket (http://www.radioshack.com/product/index.jsp?productId=2102490&cp=2032058&f=Taxonomy%2FRSK%2F2032058&categoryId=2032058&kwCatId=2032058&kw=dc+plug&parentPage=search) at the end of a 12" lead on the battery and a matching plug (http://www.radioshack.com/product/index.jsp?productId=2103614&cp=&kw=dc+plug&parentPage=search) on the light. I put the same plug on my 12v smart/trickle motorcycle-battery charger. So I just unplug the light from the battery and plug in the motorcycle-charter. This way I can also use the AC/DC brick 12v transformers that's common as well. Recharge about once a week overnight, about 8-hours on the smart-charger. :)

FREE to a good home

I have 3 [Gone] 12V markers Gone!

Ho Ho ho!

The formula is basically this:

Watts = Volts X Amps or Amps = Watts / Volts

So for every hour ("Amp/hr") of battery power you need, divide the total watts you are using (40 watts) by the voltage (12.)

40 / 12 = 3.33 or 3.3 Amp/hr. So you would need at least a 3.3 AH battery for each hour of run-time you want.

BUT--

There is a problem. The smaller the battery, the less it can carry higher wattages. For example, a battery that supports 20W for an hour might not support 40W for half an hour; it might run for 20 - 25 minutes. So you have to use "overkill" when selecting an SLA battery for your needs.

40W / 12V = 3.3 AH
2 hours X 3.3 AH = 6.6 AH
"Overkill factor" -- minimum of 7 AH (or even more.)

Remember that SLA batteries, while cheap and reliable, don't like to be completely drained. It shortens their life. ALSO--always buy a fuse for safety reasons, even a 12V battery can start a fire. You can get details from your local battery store.



ok, with this in mind... i decided to add another 10W bulb. now i've got a bouble lighting system, 30W total and i can use them together or seperate. the best part is the fact that i can use both for 75% of the time and then just the 20W(which is plenty) for 25% of the time AND still have the over kill factor of .45( 4.55 needed from a 5AH battery). that's some good stuff.... :D :D

after posting, i decided to go downstairs and take a pic.....(it's obvious i'm procrastinating with my studies)

the first pic is what i started with... the second two pics are what i have now. funny thing is, i haven't even ridden with the lights yet. i'm looking forward to it though.

Ok, so it looks as though SLA batteries can be overcharged. This can easily be solved by using a common timer...but how do you know how charged the battery really is? How can I tell how long to even set the timer for?
If you have a "smart charger," that is, a charger that knows when the battery is charged and will cut down to a "trickle charge" from full charge, you can leave it plugged in overnight, or all day. A good smart charger will have indicator lights that signal when the battery is charged and is now in "trickle charge" mode.

I forgot to mention another option to cut back on the size of your battery (or increase your run-time, if desired.) There are "energy saver" bulbs available (I use one) that allow you to get more light per watt, much like those bulbs you see for your home that draw 14 watts but put out the equivalent of 60 watts of light. Mine supposedly draws 20W but puts out ~ 35W.

In addition, the focus of the beam can make a lower wattage light seem brighter. You sacrifice some peripheral visibility, but as long as you can see what's in front of you, that's what's important. On the other hand, too wide a beam sacrifices precious visibility where you need it most.

I just about drain my battery on the way to work (one hour,) then I spend the next 7 hours recharging. I will probably go with a 5 AH eventually (like I used to have) because I like having "spare" battery power in case I need it unexpectedly.

There are "energy saver" bulbs available (I use one) that allow you to get more light per watt, much like those bulbs you see for your home that draw 14 watts but put out the equivalent of 60 watts of light. Mine supposedly draws 20W but puts out ~ 35W.

Some of those energy savers are just overvoltaged. If you run overvoltage, the filament is hotter, and you get more light per watt burned. Tradeoff is shorter bulb life. Energy saver 12v bulbs are probably just made as 10v bulbs.

MR16 bulbs seem pretty durable. I have a ride that goes over 4 miles of bumpy gravel twice a day, and I used the same bulb for a year (still have it, but my primary is now an HID). So the "shorter life" may still last a year, and if you get significantly more light, it's worth it.

Some of those energy savers are just overvoltaged. If you run overvoltage, the filament is hotter, and you get more light per watt burned. Tradeoff is shorter bulb life. Energy saver 12v bulbs are probably just made as 10v bulbs.

MR16 bulbs seem pretty durable. I have a ride that goes over 4 miles of bumpy gravel twice a day, and I used the same bulb for a year (still have it, but my primary is now an HID). So the "shorter life" may still last a year, and if you get significantly more light, it's worth it.
ItsJustMe, check this bulb out--5,000 hrs.

http://www.bulbs.com/products/product.asp?page=products&class=840

Some of those energy savers are just overvoltaged.
Are there any "Energy Saver" MR16s other than the Philips?

I've got a 10w MR-11 light right now. Don't have a regular commute or anything, so I've been using for afternoon rides where I get caught up after sunset. Probably about 1-1.5 hours a day. I have put a female DC socket (http://www.radioshack.com/product/index.jsp?productId=2102490&cp=2032058&f=Taxonomy%2FRSK%2F2032058&categoryId=2032058&kwCatId=2032058&kw=dc+plug&parentPage=search) at the end of a 12" lead on the battery and a matching plug (http://www.radioshack.com/product/index.jsp?productId=2103614&cp=&kw=dc+plug&parentPage=search) on the light. I put the same plug on my 12v smart/trickle motorcycle-battery charger. So I just unplug the light from the battery and plug in the motorcycle-charter. This way I can also use the AC/DC brick 12v transformers that's common as well. Recharge about once a week overnight, about 8-hours on the smart-charger. :)
I like your setup here and think I'm going to try to build something comparible for my power source. I think I'm going to go with a 5ah setup, so I'll probably buy these: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1158

They're cheap and I think they'll provide plenty of power for my commute if I charge every day at work. A question I have is why you built your power brick to supply 13.2V instead of a flat 12V. Is there something I'm missing here? Should I buy 11 of these batteries so that I can get 13.2V or can I get by with 10? Also, what smart charger do you recommend for this type of setup (assuming I go with the C batteries instead of your D's).

Thanks everyone for all of the great information. I'm learning a ton (and having a great time). :D

Another question for the regulars here:

Any reason (other than price) not to go with Li-ion over NiMH? BatterySpace has a sweet deal on a prebuilt 11.1V 7200mAh water bottle battery, 100 bucks including the charger:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2217
http://www.batteryspace.com/ProductImages/bike-battery/BK-Li-1440-1.jpg

It's a little more capacity than I "need", but it's only 20 bucks more than I'd spend on the NiMH battery I "need" plus charger. Plus it has lots more capacity, weighs less, and is less work than making a water bottle battery out of cells or packs myself. Any "gotchas" I should be aware of with Li-ion? Should I add an extra inline fuse between this thing and my lights just to be on the safe side?