rewiring an emergency light with tubes for LED strips

Hi there,

Maybe can someone could voice some ideas on the best path for this:

I have not one or two but 8 emergency lights, each having an internal lead- gel 6v battery, and two fluorescent tubes. The fixture plugs into 220v AC a nd when power goes out, the batt kicks in and lights the tubes, simple huh? ;-)

My main goal would be keeping the case, the battery, and as much of the cir cuitry as possible, but instead of feeding fluorescent tubes, replace those with LED strips.

I have disassembled the unit and found that the circuit board is just one, that integrates all functions, battery charger, switching from AC to batter y, and doing the tubes startup.

I've also measured the voltage of the wires leading to the batteries, and w hile the battery is 6V, I get 10 volts of charging voltage when the unit is plugged into AC -I guess this is normal-.

The tubes are a pair of 30-cm (11.8 inches) wide, labeled F8T5/D

Now, I know nothing about tubes, except that normal tubes come with a balla st and 'starter'. On this circuit board I see no 'starter' but there's inde ed a small transformer, although I'm not sure if this is related to the con version from battery DC to AC or as a step down to turn the 220vAC into the 10V used for charging.

What would be the best route to do this conversion?.

I thought that ideally, I'd keep the circuit board unmodified, and just add any additional components needed to turn whatever voltage the unit feeds t o the tubes, into the 12V DC expected by LED strips...

Now, anyone has more information on what voltage gets into these "F8T5/D" t ubes? and would the 'starter' effect used by fluorescent tubes fry any circuitry I add at the end of the wires before the tubes, to turn it into 12VDC ?

here, it only says

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"This F8T5 linear fluorescent lamp operates at 8 watts. It has a color temp erature of 6500K, a CRI of 75, and an average life of 7,500 hours. "

...but no words about voltage

yet over here

it reads:

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0

///// "Voltage

57.0 Open Circuit Voltage (rapid start) (MAX) 190.0 V Open Circuit Voltage (after preheating) Max @ Temperature 210.0 @ 10.0 V Open Circuit Voltage (rapid start) Min @ Temperature /////

So basically I'd need an IC that can turn anything from 210v to 57v into 12 VDC ?

Let me know if my reasoning so far is OK or flawed, because I've never work ed with fluorescent lights before and there's too many unknowns in my drawi ng board. :)

Thanks in advance for reading and any leads... FC

Reply to
fcassia
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As always, what you do is critically dependent on your final objective.

If these are used as REAL emergency lights, there are a bunch of regulations you need to comply with. You can't just modify them. Inspectors don't care about the specs. All they care about is that they have the right stickers on 'em.

If you just want a portable light, the LED's aren't significantly more efficient than fluorescent lamps.

And if they're emergency lights, they won't be ON enough to make efficiency an issue.

This has the possibility of being one of those projects you spend a lot of time and money on just to stick them in the closet.

Might be better to define your objective and start from scratch.

6v battery, and two fluorescent tubes. The fixture plugs into 220v AC and when power goes out, the batt kicks in and lights the tubes, simple huh? ;-)

circuitry as possible, but instead of feeding fluorescent tubes, replace those with LED strips.

that integrates all functions, battery charger, switching from AC to battery, and doing the tubes startup.

while the battery is 6V, I get 10 volts of charging voltage when the unit is plugged into AC -I guess this is normal-.

and 'starter'. On this circuit board I see no 'starter' but there's indeed a small transformer, although I'm not sure if this is related to the conversion from battery DC to AC or as a step down to turn the 220vAC into the 10V used for charging.

any additional components needed to turn whatever voltage the unit feeds to the tubes, into the 12V DC expected by LED strips...

tubes?

add at the end of the wires before the tubes, to turn it into 12VDC ?

temperature of 6500K, a CRI of 75, and an average life of 7,500 hours."

formatting link

?

replace the 6V with 12V batteries and build a charger.

with fluorescent lights before and there's too many unknowns in my drawing board. :)

Reply to
mike

First, thanks for reading me and replying Mike!

ons

These are inside my home. Down here at least there's no rules or regulation s (or inspections for that matter) about what one installs in your own home .

Yes I can. ;)

There are no inspectors. :)

I want to get a light that can withstand a 2-hours long power cut like happ ens often in mid summer amid a heat wave, instead of the paltry 15-20 minut es I get from flourescent tubes. Given that leds can use 3-4 watts vs 2 tub es x 8 watts each = 16W, I' d say that the increase in time will be signi ficant with regards to how long the lights will last in case of outage.

What's even better, I already have the 12V LED strips and the old fluoresce nt fixtures and batteries, so in my view what's left is some clever design (voltage regulator?) and some soldering vs buying completely new LED based fixtures.

I hate throwing away perfectly working kit.

Well it depends. there seems to be a market for this type of conversion... here for instance I found someone selling replacement 'tubes' that use leds inside but which are direct replacements for F8T5 tubes... but in the link ed videos they bypass the ballast, which is a separate board... in the boar d I have everything is in a single board (charger etc).

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So maybe I thought if there's some clever multi-purpose voltage regulator I could use to turn whatever the unit feeds to the tubes (including voltage spike for tubes warm up) into 12VDC ... I was thinking that maybe some read y-made module used for charging batteries, RC toys or something?

Just thinking aloud... but thanks for your reply and ideas. Comments are we lcome. :)

FC

Reply to
Fernando Cassia

6v battery, and two fluorescent tubes. The fixture plugs into 220v AC and when power goes out, the batt kicks in and lights the tubes, simple huh? ;-)

circuitry as possible, but instead of feeding fluorescent tubes, replace those with LED strips.

that integrates all functions, battery charger, switching from AC to battery, and doing the tubes startup.

while the battery is 6V, I get 10 volts of charging voltage when the unit is plugged into AC -I guess this is normal-.

and 'starter'. On this circuit board I see no 'starter' but there's indeed a small transformer, although I'm not sure if this is related to the conversion from battery DC to AC or as a step down to turn the 220vAC into the 10V used for charging.

any additional components needed to turn whatever voltage the unit feeds to the tubes, into the 12V DC expected by LED strips...

tubes?

add at the end of the wires before the tubes, to turn it into 12VDC ?

temperature of 6500K, a CRI of 75, and an average life of 7,500 hours."

formatting link

?

with fluorescent lights before and there's too many unknowns in my drawing board. :)

Can you not just take the output of the battery to drive the LED's ?? You would need to intercept that output into the flouro driver cct.

Reply to
Rheilly Phoull

(or inspections for that matter) about what one installs in your own home.

often in mid summer amid a heat wave, instead of the paltry 15-20 minutes I get from flourescent tubes. Given that leds can use 3-4 watts vs 2 tubes x 8 watts each = 16W, I' d say that the increase in time will be significant with regards to how long the lights will last in case of outage.

fixtures and batteries, so in my view what's left is some clever design (voltage regulator?) and some soldering vs buying completely new LED based fixtures.

here for instance I found someone selling replacement 'tubes' that use leds inside but which are direct replacements for F8T5 tubes... but in the linked videos they bypass the ballast, which is a separate board... in the board I have everything is in a single board (charger etc).

could use to turn whatever the unit feeds to the tubes (including voltage spike for tubes warm up) into 12VDC ... I was thinking that maybe some ready-made module used for charging batteries, RC toys or something?

welcome. :)

Ok, if you're intent on using what you have, what do you have? Are the led strips just leds or do they have any regulation capability? What is the minimum/maximum voltage for the nominally 12V led strips. Current vs voltage?

I'd disconnect all the fluorescent stuff and build a current-mode boost converter that runs off the 6V and supplies 12V to the leds. Exactly how depends on exactly what's in the led strips. Leave the charger alone.

IF you can cut the strips in half and parallel them as 6V, you may be able to add a resistor to limit the current at the maximum battery voltage and be good enough.

Or you might be able to rewind the transformer and use the existing high voltage supply to get 12V.

There are solar powered outdoor lights. Local dollar store has them for a buck. They turn on when the sun goes away, so just replace the solar cell with charge current. They don't put out a lot of light, but will keep you from stumbling over stuff. Use a lantern at point of use. Or just turn on the fluorescent components when needed. The chip is QX5252. problem is that it's designed for one or 2 1.2V rechargeable cells and 1-2 leds. Depending on who made the light, the chips are removable or bonded directly to the board and covered with a blob of epoxy.

Are we having fun yet?

Reply to
mike

d-gel 6v battery, and two fluorescent tubes. The fixture plugs into 220v AC and when power goes out, the batt kicks in and lights the tubes, simple hu h? ;-)

ircuitry as possible, but instead of feeding fluorescent tubes, replace tho se with LED strips.

, that integrates all functions, battery charger, switching from AC to batt ery, and doing the tubes startup.

while the battery is 6V, I get 10 volts of charging voltage when the unit is plugged into AC -I guess this is normal-.

last and 'starter'. On this circuit board I see no 'starter' but there's in deed a small transformer, although I'm not sure if this is related to the c onversion from battery DC to AC or as a step down to turn the 220vAC into t he 10V used for charging.

dd any additional components needed to turn whatever voltage the unit feeds to the tubes, into the 12V DC expected by LED strips...

tubes?

y I add at the end of the wires before the tubes, to turn it into 12VDC ?

mperature of 6500K, a CRI of 75, and an average life of 7,500 hours. "

ED_PROD...

12VDC ?

rked with fluorescent lights before and there's too many unknowns in my dra wing board. :)

For starters, something is wrong with your voltmeter. There are no 6V lead-gel batteries that tolerate more than 8.0V while charging unless the battery is defective.

Reply to
hrhofmann

simple huh? ;-)

tubes?

12VDC ?

reads:

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12VDC ?

I was thinking the battery is defective.

Where is the OP ?

You have to define your lighting needs. What you have or had, is that perfect ? There are strips that run 12 volts. You can add strips to get more light. The old circuitry is useless. You probably need batteries, so it would be better to start from scratch.

Greg

Reply to
gregz

Maybe I will have to re-do the readings. I used an ancient analog tester.

In the unit I have currently disassembled, yes. The rest of the fixtures, no, the batts were working perfectly when the units where removed.

Here, here. I'm just not glued to the puter 24/7. :) and I read this whole thread. Thanks to everyone.

Yes.

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I know, thanks.

better to start from scratch.

Hmmm it seems to me that there is more people interested in proving that my idea is silly than people thinking about a creative solution to turn the variable AC output leading to the fluorescent tubes into 12VDC. ;-)

But thanks anyway for the "constructive discouragement". JOKE JOKE

Best, FC

Reply to
Fernando Cassia

With a buck-up converter, yes.

Fluorescent drivers, now we're talking. Keep in mind I never worked with fluorescent tubes before, so I didn't know there was a thing called 'fluorescent driver' to begin with :)

Now looking at the board, I see one Fairchild semi KA7808 1A voltage regulator, and two HS882 3-pin ICs next to test pins labeled 'output 1' and 'output 2' which surely means for tube#1 and tube#2.

Looking at the HS882 it's a 'switching power amplifier'...

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hmmm...

food for thought... but no more ICs... after your comment wrt 'fluo driver' I was expecting it to have something like this

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but it doesn't.

FC

Reply to
Fernando Cassia

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