battery pack

[Greg Howald]

We get a lot of power outages here, especially during the winter months. So I made a battery pack for one of my LED microscopes using an 18650 battery and charger. I was afraid that 4.2 volts would be too high for the LED bulb so I placed at 35 watt halogen bulb in series line with the battery pack to reduce the voltage. It works well and I won't be interupted again because of power outages. When I plug it in to AC voltage it will still charges the battery. I thought it was a good idea and wanted to share this info.
The LED light looks about right so far as intensity is concerned.
Greg

[MicroBob]

Hi Greg,
very good idea! For bright field LED use there is not much power needed anyway.

Many of these 18650 lithium ion batteries on the market are fakes: Capacities of 5x the possible maximum but inside only a little battery connected with wires to the poles . Easy check: A proper 18650 weighs about 50g.

Bob

[Chris Dee]

I can imagine the frustration of an outage after preping wet slides for a session. Good idea Greg.

[Greg Howald]

Last night I added a 0-1500 ohm potentiometer which gives excellent control over lighting intensity.
Greg