Modifying a 50W Halogen spot light

[jasonck08]

@ electromage thanks for pointing out those batteries. But, I'm in Taiwan and shipping rates would be more than the cost of 12 batteries. They wanted $22.20 for 12 AA's, and $25 for shipping!!! A USPS Flat rate global Priority Mail envelope is only $11 regardless of weight.

@ Mr Happy the reason for the 55W bulb is I wanted to overdrive the bulb and for it to be brighter than the stock 6V 55W bulb. Putting a 12v 20W bulb in a big spotlight seems a little silly, unless I could overdrive it a lot. Could anyone recommend a 20-35W 12v bulb that I could overdrive very well???

 

[Mr Happy]

Sorry, I missed that it was a spotlight.

They tend to put lead-acid (SLA) batteries in those spotlights because they need a big power supply for the powerful bulb. Such big bulbs are really not compatible with AA size batteries. Even if you get the right NiMH batteries to supply the current needed the run time would be really short and recharging would be complicated.

However, you could try to return the light to its original working form by finding a replacement 6 V SLA battery perhaps?

 

[jasonck08]

I charged up 16AA's and connected them all to my 12v bulb. The fully charged AA's were putting out 22v. When connected to the 50W bulb, the voltage remained around 13.2v, so it was slightly overdriving the bulb. I did not do any resistance mods to the battery holders. They are very cheap things. 2x8xAA holder that I bought for 50 cents each.

 

[Patriot]

It sounds like you finally made it work.

What are you going to use the light for now? I was curious because I don't imagine the run-time will be very long.

 

[jasonck08]

Well with the cells and the amount of load and resistance, I figured all of them added up together is about 25-30 watt hours worth of power. So a slightly overdriven 50W bulb would be sucking about 55-60W's. So thats still at least 20-30 minutes of run time...

The spot light originally was about 10 minutes of run time, and not nearly as bright. I will shine the spot light from the 12th floor and light up the city. It's more of a fun light than practical. I have an SSC with over an hour of run time @ 120 lumens and 16 brightness settings. So thats my practical light.

Also, the spotlight needs a new switch. And the battery compartment is aluminum and has four screw holes securing the plastic back side that holds the rubber in. I might just get some thumb screws so I can remove the batteries without tools.

 

[TorchBoy]

Interesting project - if at first you don't succeed, add more power! Did you end up with 16 identical cells? Eneloops would be good because they have a low internal resistance and will give you a slightly higher voltage under load than many other NiMH cells will.

BTW, current is measured in mA or A while capacity is in mAh or Ah. SilverFox has measured Eneloops up to 10 A, and they held up quite well.

I have a 100 W, 6 V spotlight which will draw almost 17 amps when the battery is fresh. Eventually the switch died and when I took the poor melted thing out I found it had a rating of only 5 amps. I replaced it with a good toggle automotive switch. It was even an illuminated switch, but I had to change that little bulb (to LED) since it was for 12 V.

 

[Flashanator]

hey TorchBoy, I use 8amp switches on some home made lights I have drawing 11amps. Do you think mine will melt if I run it too long?


And what about lights like 15MCP using 130w H4 which draw 11amp? Do they use 8amp switch too?

thx.

 

[TorchBoy]

It should be able to cope with a little overcurrent - the 5 amp pushbutton switch certainly did, and for a surprising amount of time.

Sorry, I have no idea what other spotlights might use for switches.

Something I've thought for a while is the 15 Mcp figure sounds quite weird. My 100 W spotlight is a claimed 2 Mcp. I can't believe the spot is 5+ times more focused to make an intensity that much greater. On the other hand, all the figures for 25 W (500 kcp), 55 W (1 Mcp) and 100 W (2 Mcp) spotlights around here are quite consistent. It's just the 130 W spotlights that have the incredibly inflated figures.

 

[tamas970]

Sorry for reviving an old thread. I am planning to convert an old dive light, that used 10 F-size NiMH cells to produce 12V to lithium.
The problem is, that with the normal 3.6-3.7V I end up either at ~10.8-11.1V (minus the resistance of the system...) or at 14.8V.

The question is, does a socket g6.35 halogen bulb survive 14.8V at all? Somewhat reduced lifetime is not an issue, these things are cheap.

LED conversion is also planned for the light but I'd like to try it as halogen, provided the nice warm color temperature and high cri of the
bulbs.

 

[broadgage]

Sorry for reviving an old thread. I am planning to convert an old dive light, that used 10 F-size NiMH cells to produce 12V to lithium.
The problem is, that with the normal 3.6-3.7V I end up either at ~10.8-11.1V (minus the resistance of the system...) or at 14.8V.

The question is, does a socket g6.35 halogen bulb survive 14.8V at all? Somewhat reduced lifetime is not an issue, these things are cheap.

LED conversion is also planned for the light but I'd like to try it as halogen, provided the nice warm color temperature and high cri of the
bulbs.

What was the originally intended purpose of the 12 volt bulb used in your light ? If it was intended for vehicle use then it will be designed for about 13.5 to 14 volts and will be fine slightly overdriven at 14.8 volts, life will be reduced but as you point out bulbs are cheap.
If however the bulb was intended for decorative or display lighting, line powered via suitable transformer, then it will be designed for a true 12 volts and 14.8 volts might be a bit much.
If the lamp is a small projector lamp designed for high output at the expense of lifetime then 14.8 volts will probably kill it.

 

[tamas970]

I haven't done the bulb shopping yet, however it will most likely be an Osram 64623HLX G6.35 piece. The osram datasheet says it has a nominal 2000h lifespan, however doesn't mention anything about overvoltage (which eventually happens with NiMH too). I just got an old I am considering all options.

The main objective is to get a high CRI (90+) light for video, powered by high energy density batteries. If I don't find a LED alternative, I'll check around durable bulbs.

What was the originally intended purpose of the 12 volt bulb used in your light ? If it was intended for vehicle use then it will be designed for about 13.5 to 14 volts and will be fine slightly overdriven at 14.8 volts, life will be reduced but as you point out bulbs are cheap.
If however the bulb was intended for decorative or display lighting, line powered via suitable transformer, then it will be designed for a true 12 volts and 14.8 volts might be a bit much.
If the lamp is a small projector lamp designed for high output at the expense of lifetime then 14.8 volts will probably kill it.