About all the work to do , is there a problem to run the led to hard for like 5mins? I only want to change the momentary mode to like 200% (I know these are stupid numbers but you understand) and the normal 100% to the current momentary mode of 130%.
It
might not damage the LED if it was attached directly to the heatsink, but with that thin metal stalk there, and assuming the light already drives it at something approaching its rated power, 200% would most likely be way too much.
How long could I use it before really damaging the led?
Take current readings and we'll be able to tell you, but don't expect good news.
Can I connect the multimeter on the red and black cable to read the current?
No, that's how you read voltage. Connect black and red with the meter in current mode and you'll short everything.
You need to do the following:
1) unsolder from the LED either of the two wires while leaving the other one connected. In your place I'd unsolder the black one, because if the red one touches the body of the light it'd most likely short out (most light bodies are grounded to negative).
2) put the multimeter in current mode. You need to find the A settings (for Amperes); there are likely two or three settings (may require you to move the cables on the meter), and you might have AC current mode on the meter. You want DC mode, which is represented by a symbol like
this (as opposed to AC current, which has
this symbol and is useless to you right now).
Your meter most likely has a settings for milliamps (probably the "20m" you mentioned) and either one or two settings for higher figures, typically a 1A or 2A setting (possibly a 200mA as well).
You need to place it on the highest setting, which is going to be 1A or 2A, or maybe 10A for particularly versatile meters. Carefully look at the probe connections on the meter - it's likely you have to switch the positive lead to another connection, typically the one that reads "UNFUSED" with a big fat warning sign nearby.
3) turn on the multimeter
4) turn on the light. This being a simple resistored design, you don't have to worry about running drivers unloaded.
5) connect one probe to the wire you unsoldered, the other on the solder tab on the LED itself. Be careful not to bump the lens on the LED: if bumped hard enough it could detach ruining the emitter.
6) as soon as the circuit is completed the emitter should light up, and you should get a reading on the multimeter's display, something like 0.7 or 0.75. Be sure to have a steady connection inbetween the probes and the contacts; if the number on the meter keeps changing, it means you need a better connection (you might need jumper wires).
6) switch the light to low mode; the value should now change to a much lower number.
7) turn everything off, solder the black wire back on the LED.
You now have the current values. Post them here.
🙂
By the way, you
are using NiMH cells in this light, right? You're not running it on alkalines, I hope?
