forgot to charge my light and it dropped to low power mode 10minutes in to the morning commute, not too bad as it was getting light but I’ll be knackered for ride home. Can I charge my lights with a standard dc power supply (same V/A as the charger) without damaging them? Just wanting to charge them to half full, couple of hours or so, no need for a full charge so the lack of cut out/trickle charge shouldn’t matter.

http://batteryuniversity.com/learn/article/charging_with_a_power_supply

Yeah I had a read of that before posting. Sounds doable, just not sure how much damage could be done. That looks like it’s mainly talking about basic batteries, dunno how battery packs used for MTB lights and similar, differ – if at all.

Done it with a rechargeable LED work light we desperately needed for a job and couldn’t place its dedicated charger, just kept a serious eye on it as it charged ,with constant regular back of the hand temperature checks to make sure it wasn’t getting hot. Back of your hand is more sensitive to heat than the palm or fingers

If the voltage matches then you can do it (although that seems unlikely, all my dedicated chargers are an odd voltage). There may be some cleverness in the charger that shuts it off when they are full. If the cell is protected then they should do the same so normally belt and braces. If you have neither of these features then you risk overcharging the cells which will lead to an explosion and/or fire. You could give them a fixed time just don’t forget. We had this in the lab a few years back from one of our electronics consultants. Filled the whole room with smoke and left a nice imprint on the lab bench.

Cheers for responses, usually takes >4hrs to charge fully so figured a 2hr charge should be safe but still be enough to see me home.

Check the power supply is the correct polarity.
Most of them are standard, but there are a few bike light batteries the wrong way round (eg Lumicycle).

Keep an eye on while its charging – if it gets abnormally hot then turn it off. Your supply might not be current limited which could be interesting 🙂

What light or battery pack is it? Cheap Chinese import you’ll be no worse of that using the provided charger.
Not sure where hope/exposure/lupine/Gemini etc put the “smarts” but given exposures charge off of a USB cable must be in the light.