I was thinking of purchasing security lights the ones that are solar powered but I don't know if there are powerful enough or if they can be modded with a better LED. Has anyone purchased one or seen them in action?
I'm modifying one at the minute with 3xXML-U2 and a DX driver. Will run on 13v @3A though. The solar cells on the rechargeable ones aren't generally very high output so you might struggle to get enough charge into your batteries to power anything too bright
Usually the solar cells aren't good enough, they're low output and cheap, that's why the lights are generally rubbish. You could measure the output of the cell and try to build a charging circuit for a load of 18650's or similar. For something really bright you'd want 3/4s, then however many parallel for runtime.
You guys know that there are security lights with good l.e.d.s right? They just won't be solar powered. Home Depot carries 1700 lumen 2 head security lights for under $100. They probably use Cree XM-L l.e.d.s. If you want solar powered, I suggest modding those instead of trying to mod low output solar ones. With low output ones, you might have issues with heatsinking.
I've used and installed most of the available solar security(motion sensor) LED lights. They are lacking in quality. Some need waterproofing. Others don't work when cold out. If they are triggered too often, the battery will live a short life. I had no problem working around these issues.
My favorite are the Maxsa 80 and Maxsa 100. Sunforce, HeathZenith, Concept, Flipo, Coleman, Solar Goes Green,... are pretty good too. Lowes and Homedepot have a couple worth looking into. 200-400lm for a minute or two is typically all that I need to prevent tripping across the yard, making the key find the lock, letting the dog out, taking out the garbage, or illuminating the creepy neighbors walking by. Their sole purpose is a few minutes of light when needed, where there is no other power, and when you don't want to hire an electrician. Most have enough battery capacity for 30-60minutes if you have a busy night. But, don't expect the battery to tolerate that much usage regularly. If you understand their capability, you won't have a problem.
I don't see the point of upgrading their LEDs since these are cheap generic solar security motion lights. You are very limited to their battery size and solar panel capability. And some still use bunches of 5mm LEDs instead of a single Cree... You can squeeze of few more lumen but its not worth the effort. But, if an LED burns out, get that Nichia or Cree in there!
When they do fail, the 1st thing to do is test the battery. The cheap imported battery will fail on its own even if it wasn't mounted in a solar trickle charged situation.
The other common failure is soaked electronics. This is when you exercise the warranty or your modding/repairing skills. Make sure you break out the caulking gun or a tube of clear RTV, aquarium sealant.... and waterproof it prior to installation. Keeping the light under an eave sure helps here.