Converting 20W, 230V LED tube light to run on 12V battery

I have a 65Ah sealed lead acid battery, which I charge with my 180W monocrystalline PERC solar panel using a Pulse Width Modulation (PWM) charge controller. As part of making the whole radio room run on solar energy, I have a 1150W inverter which can run my pedestal fan and LED tube lights on 230V AC. Then I thought that if I can bypass the inverter by using 12V LED tube light, that might save some energy loss due to conversion. I had posted about the internal structure of a 20W, 230V AC LED tube light earlier.

The LED strip inside the tube light contains a total 87 LEDs. There is a driver unit along with it. If one LED needs 3V, the 87 LEDs in series would need 261 VDC output from the driver circuit. Just to check it out, I connected mains power to the AC input of the LED driver unit. The input AC voltage was around 216V.

Output of the driver unit was seen to be around 120V. That would mean only about 1.38V per LED, if all the LEDs were connected in series. That was rather odd as most white LEDs need 3V for illumination. There could be some error of measurement in my old digital multimeter or the output may not be a true DC. Still the AC input measured by the same digital multimeter seems to in the reasonable limit for a 230V rated mains supply in this region.

Inset on the right side with blue border shows three copper strips between each LEDs after scraping off the insulation with the sharp edge of a small pair of scissors. The broader central strip connects the LEDs in series, while the narrower strips on either side are the positive and negative supply lines coming from the driver unit.

In the pink bordered inset on the left side, middle of the central strip can be seen as cut with a sharp screw driver to disconnect the connections between every 4th and 5th LEDs in the series.

Video clip shows checking of continuity between two sides of the cut central strip. Aim is to have no continuity between the two sides of the strip. It takes a little bit of meticulous work with the screwdriver tip to cut the strip, without damaging the positive and negative lines on either side. Occasionally they do get damaged when the screwdriver slips. Now the LEDs are in groups of 4 so that 3 x 4 = 12 will be the voltage needed for them to glow when connected to the battery.

Here is a demo of a group of 4 LEDs being lit up using a 12V battery. A green heat shrink piece has been placed over the LEDs to protect my eyes being damaged by looking directly at the bright light from a short distance.

Now comes the tedious job of connecting 21 sets of 4 LEDs each together to 12V battery. Not sure whether the thin positive and negative strips will take the higher current at lower voltage for long duration without heating up. That would be 20W/12V = 1.67A. While working at higher voltage, like the 261 VDC which I had calculated initially, the current need be only 20W/261V = 0.077A.