Originally Posted by MWPdx
So I picked up that pond light the other day. I kinda played around w/ it a little with just the stock (mr11) bulb and a 12v sla battery that I have on my bike already for my horns. First off, I LOVE the color of light that this puts out (way better than the bluish white like most leds I've had, IMHO). It seems way floody and not as super bright as it looks in the diy pics on here and other forums.
I know that the mr16 bulb (at least the spot one) will be less floody but is there another reason to get a different bulb?
Also how much of a difference is made just by over volting it?? It'd be nice if it was brighter and to have a non SLA battery (I keep worrying that I'm gonna mess this one up) but at $70-100 for the battery/charger setup, I wanna be sure it's worth it.
The beauty of halogen is that you can get reflectors in all kinds of beam angles. From 7 degrees to 60 degrees
. In the hardware store, they are usually listed as a spot light (12 degrees) or a narrow (sometimes) flood light (24 degrees) or a floodlight (35 degrees). For riding purposes, I find that the 12 degree works well if you want a tight beam...like on a helmet...and the 24 degree works well as a flood (one on the handlebar). Anything wider is usually just wasted light.
One note: I did purchase the 7 degree light and tried it. It was an extremely focused beam but the reflector is longer than the other reflectors and it didn't fit in the mount correctly.
As for batteries and overvolting, you can see about a 2 fold increase in light output by increasing the voltage by 20%. That's going from 12V to 14.4V. There is a 90% reduction in bulb life, however. That may sound like a lot but considering that the MR16 bulbs usually have lives on the order of 5000 hours, you still end up with 500 hours of life. That's still a bunch
To give you some indication, I have been using overvolted halogen for almost 20 years. In that time, I've had only one bulb blow out on me. I usually ride 50 to 60 days when I need lights per year and about half of those require lights on both ends of my commute. That's roughly 90 usages per year. And the bulbs are cheap
For batteries, use RC car batteries. Relatively cheap and readily available. Look here
for details and links. I have found some very cheap RC batteries on Ebay. They are Chinese batteries and they claim 6800 mHr which would translate to a 4 hour run time on a 20W bulb. I don't know if they are any good but they are cheap.
I would suggest that you not go below about 3000 mHr on the capacity rating, however. Halogens are energy hogs.