# Want to Convert Existing Emergency Lamp Into Solar.

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Hi Guys,

I have worked on a small project of Solar & successfully executed it. (Will post in detail later).

But now, I need your help to make my new project.

I have an emergency lamp. Which is having:-

1. a 6v 4.5ah sealed lead acid battery.

2. An electronic charger (in built) instead of a conventional 6-0-6 or 9-0-9 transformer.

3. An electronic ballast with auto power on when the current goes off.

4. 18 watt T8 fluorescent tube.

Now,

First of all, please suggest me for following:

1. Replacement of 18 watt T8 fluorescent tube with SMD LED.

1.1 What should be the number of SMD (Ex.5724 SMD LED, Bright white)

1.2 How should be they connected in order to make it a 9 to 10 watt system (max). instead of 18w.

1.3 Please let me know any register is required.

1.4 I don't want to use any IC in this. It should be very simple.

2. I will be using 6V 4.5 AH SLA battery.

3. I want to eliminate the electronic circuit & want to charge the battery through solar.

4. What voltage & current I should note while buying the solar panel.

5. Number of blocking diode to be used.

Attaching sample pictures of SMD board I am using in my previous project. But that is 12v system.

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## 5 Discussions

For 6v operation you should use 2 led in series( most of white led have 3.3v forward voltage) and also connect a 10 ohm resistance in series with two LEDs to limit the current max. 20mA

You have to step down 12v DC from solar to 6V. Or you can use 12v battery instead. 2nd thing is that LED voltage is 3v. You can connect 2 led in series for 6v operation or 4 leds for 12v operation. Resistors should be used to avoid over current. You can calculate resistance value by R=V/I formula, where i is current consumed by led in amp and V is the voltage drop across the resistor. Your solar panel should not be very powerful than battery typically C/10. Your battery is 6.4Ah so max. Charging current will be 6.4/10= 0.640 amp. You can use 1 amp current for charging but it will heat up the battery.