I have a 13.2 volt "Classic" water bottle Niterider NIMH battery with a flood HID headlamp. Both are about 3 years old. The battery has been charged over 300 times. Last night, with a fully charged battery, the HID light would go on but would never get up to full brightness. It stayed on at half brightness for three hours and I thought that maybe the battery was going bad. Afterwards, I tested the battery on a volt meter after charging it and it puts out 15volts with no load. I assume the battery must be okay but how can you tell for sure? My reasoning is that if there were a bad cell in it, it wouldn't produce that much voltage. As for the light, I'm not sure how HID bulbs act when they are going bad. It's not like an incandescent bulb that just dies when the filament breaks. Any advice on this would be much appreciated.

If I could just find a 13.2 volt, 4 amp hour Li-ion battery, that would be way lighter and give way better runtime than the $160 ripoff NIMH battery. Niterider is really proprietary with their products and will never offer any advice to owners tweaking or modifying their lighting systems. They will just tell you to send it in to them and they will never offer any technical advice on such matters. Does anyone out there have a home-made lighting system? I wish I could fix my light without coughing up the megabucks for the proprietary $160 battery, $100 bulb or $85 charger. I'm sure those parts are not worth anywhere near that much, it's just they can charge owners that much because they've got you by the cohones.

There is no indication that your battery is bad. Once in a while the circuitry in some Nightrider HID lights go bad. It has happened to me. They fixed it for free. It sounds as if you may have a simlar problem (just a guess).

1) Call them and ask if it sounds like you need a new bulb. If they say no, get a retuned goods authorization number. (Don't email) This gives them a way to tie your light to the explantion you give over the phone. They don't care if you have a receipt or not, they just fix it.

2) Send them your light. If it is a problem that was Nightriders fault they will fix it for free. If it's something you did they will tell you and you can decide to have them fix it or not, it's up to you.

3) There are no "deals" on HID bulbs. It costs more to get something from the manufaturer than the Nightrider factory. You are stuck with that. You may ruin the light if you try and run a headlight made for NImH with Li-Ion.

Batteries can produce their nominal voltage but if they are defective and have a lot of internal resistance, they will not produce their rated current at that voltage.

Niterider won't fix the light for free. They charge $40 labor just for looking at it and a new ballast is $48. I'm thinking of just getting a new Trail Tech MR11 instead.

HID bulbs wear out every time you start one up. it could just be an old bulb

also the outer bulb can crack, and the inner part can be fine, so what happens is
the heat from the plasma starts to degrade the outer relective layer. when the
bulb is intact, the outer bulb has a rare gas that prevents the reflective layer
from vaporising. so what may be happening is the bulb is vaporising and degrading
it's reflective layer, getting dimmer

happened to mine after a crash. bulb would light, but after a few rides, it got dim fast.
closer inspection showed the reflective layer eroding from the edge, and getting worse
as the days went by

It depends on what is wrong with the light. I got two different Nightrider lights repaired for free and shipped back for free. If the problem was caused by something that was Nightriders fault they will.