Rewiring 110 volt Led Christmas lights for 12 volts

[Norm]

I was already in the process of rewiring 110 volt Led Christmas lights for 12 volts
when I ran across this site which I found very helpful.....

http://michaelbluejay.com/batteries/dc-christmas-lights.html
going to the bottom of the page and just before the first step
explains how to hook up 4 bulb for each string.
However since my NiCad batteries are 12 volt, I figured 5bulbs
per string, going to have a total of 50 LEDs so according to this
would be about 25 watt/hrs. not too bad.....this is where someone
like me pedal generating is what I do in an hour 50 watt/hrs per day.
Can really appreciate how much work electricity does for us.

On the way down on his site....he has some interesting info about
batteries and such which might be interesting to ones new to LEDs
and such.

Norm

[Bruce S]

Hello Norm;
That is a very interesting site to read. His battery Chemistry link is pretty interesting too.
Thanks!!
Maybe those 6V sticks you're working with will work out better for longer run time?
Cheers;
Bruce S

[Norm]

Bruce....these seem to hold up for about 3hrs. from 12.8 to 11.8v

thes are the rewired ones

only 40 for now....10 more to add...
[ Specified attachment is not available ]
These are the regular 110 v. LEDs hooked up to
an inverter running from a sla 75 amp/hr. battery
charged with pedalpower 50 watt/hrs. per day and
gradually losing it about .3 of a volt per day
course I had it on a few hrs. during the day....have to
start turning it on only after dark?  duh...
Wanna come down and give me a hand ....er feet?
don't have the hand powered mode yet.

Fun fun fun !
Norm.

[Norm]

whoops left out a pic.
these seem to hold up pretty good....
update you on these after a couple of days...
if they don't last long enough I've got enough of these
I can add 2 or 3 or 5....LOL.


Norm

[Bruce S]

Norm;
 NO where near as cool as yours.
Here's ours. I like the way the stubby LEDS makes the aurora from the flash on the camera

Didn't get battery in PIC but it's a hold over from the 16Ahr mega-packs.
Hey that 5Ahr 4-by looks great!!
Hows it holding up?
Merry Christmas
Bruce S

[ghurd]

I hope everyone rewiring Christmas LED light strings for 12V use remembers to inclued the current limiting resistors.
G-

[Norm]

Hey that 5Ahr 4-by looks great!!
Hows it holding up?


Pretty good...but it need equalizing....some of the stacks
arent like 6.7 ...like one was only 5.43 and another only 5.9
for example and the whole thing read 13.2  as a result after
2hrs. it had dropped down to 11.7 . they seem to get dim
under 12 volts.....but I'm sure they would last a good 2 hrs.
so for 6 hrs 3 or 4 would be good enough.
Okay maybe they'll last 3 hrs. that must have been the bad
one....the one I have on now started at 13.6 and after an 90
minutes its down to 13.24.
that's the one in the kitchen window with about 40 bulbs and so
that's about 4 watts.
Not too bad is it?

Now the set up in the frontroom ....the 12volt SLA  75 amp/hr pedal charged
by my PedGen running a 400 watt inverter to run 50 LED christmas
light in the window....about 4.5 watt according to the box.
battery fully charged run lites for an hour and the voltage drops from 13.6
to 12.9 so I pedal for about 5 minutes at a leisure 30 watts and the voltage
goes up to 15.5 and the inverter cuts off over voltage so I have to slow down
for 5 minutes....(10 min. is about 5 watt/hrs)

I pedal this at a leisurely 40rpm if this where a real bike with a wheel and sprocket
this size I would be traveling 3.5 MPH. in 10 minutes I would travel about .5 mile.
so thats about it.....
for now
Norm.

[Norm]

I hope everyone rewiring Christmas LED light strings for 12V use remembers to inclued the current limiting resistors.
G-

Thanks Ghurd....was in the back of my mind as I noticed that the original 110 setup is
actually a full wave rectifier...you might say with 25 diodes for one way and 25 diodes for
the other way with resistor for each set.
and what value resistor would you suggest? just one resistor for the whole thing
or 1 for each series of 5?
and thanks again....they haven't any of them blown so far but I'm just lucky until
I get some resistors in that circuit.....I wouldn't want anyone blaming me for the oversight
of mine.
I was wondering why the guy in the article didn't say anything about this.....Maybe he gets
them so cheap he figured it wasn't worth the extra effort?
Norm.

[Bruce S]

Norm;
I'm thinking like you, there must be a bad cell in there some where.
I looked long and hard at his posting and he has them setup so the string drops the voltage enough he doesn't use current limiting resistors.
Like G- said I include resistors in each 4-bulb string. I know 3 would be better, but try having your Christmas cookies held back until the lights are done!!
Here's my pack.

I would NOT suggest anyone do then this way. Works but I have to keep an eye on the thermal interior while on a deep charge.

[Norm]

I guess for now this is working without resistors....
5 per string about 8 strings paralleled.
These 5.2 paks can only get charged to 13.8 very
hard to get them much higher and by the time they
are ready to use they have dropped down to 13.8
anyway....I even had one that stayed at 13.8 after a couple
of days just laying around.
So this one is like this after using it on these 40 leds for over
4 hrs. it had dropped to 12,4 .....so 2 of these 5.2 paks in real
good shape should last 8hrs.
Takes about 40 minutes of 3.5 virtual miles to charge both of them
to the hilt ! .....and I mean leisure! picture you pedaling a tricycle
 with a wheel big enough that you could pedal at 3.5 mph
with a crankspeed of about 40rpm.
So that's about 20 watt/hrs.
Hey I can even make pancakes in between pedaling !
It works like this....
Pour 3 tablespoons of batter onto the pan.
walk over and pedal for 2 minutes.
back and flip the pancake.
walk over and pedal for 1 minute.
back and put on plate.
pour 3 more tablespoons....etc.
6 minutes and 3 watt hrs later......2 golden brown 4 inch pancakes!
6 pancakes and I charged 5.2 battery.
Norm.

[Bruce S]

Norm;
 Put on just a few more of those please!! and maybe a extra scoop of grounds in the coffee pot, you're making me hungry 
For the NiCds 13.8 is REAL good!! on our super-duper 6G testing machine completed tested NiCds read 1.47Vdc this has one of those thermal probes and even does the fancy reverse pulse for NiCds.
SO if you're reaching 13.8 for a 10-cell pack and full would read 14.7vdc then you're reaching 93% that's good enough for me  .
And certainly good enough for the NiCd to stay nice cool with a good work out, like they like to be.

The extra work you're feeling when they get up to 13.8 is the resistance of being charged even more that leads to the heating effect.
I think you've got them dialed in perfectly sir! especially with those pancakes cooking.
Cheers;
Bruce S

[Norm]

Guess I'll have a midnight snack of pancakes and coffee....
as I work on a second set of 50 for 12volt. these are the
C6 enclosed in the crystal globe just it is colored the LED inside
is white.....on sale at Walgreens for $6.96.....
Norm.

[Bruce S]

I kinda noticed those too while getting that one last present for a grandkiddie
Sorry I couldn't stop by, the sleigh was commandeered for shopping 
It would be interesting to see what a meter would show on the current drain.
I know math can tells us what it is supposed to be , BUT that's no fun!!
Let me know when you get low on those batteries. I have a fresh batch of ones that just came in and all are testing REAL nice!!
I'm going to bring up two more of the 20Ahr ones, The GHurd controllers seem to be working perfect dialed in at 13.5+.
3 of these will top out my HF panels and I can worked with the older units for the ECM.
Merry Christmas!!
Bruce S

[wooferhound]

Here is a great page to help you design LED Lighting
http://led.linear1.org/led.wiz

When inputting values into this LED Wizard, use
20 for "diode forward current (mA)"

"diode forward voltage" will depend on the color you are trying to use
White is about 3.5 volts
Blue, Violet, Purple and Ultraviolet is 3 volts
Green is normally 2 volts, but can be as high as 4 volts depending on type
Infrared, Red, Orange and Yellow is 2 volts

[ghurd]

Thanks Ghurd....
I was wondering why the guy in the article didn't say anything about this.....Maybe he gets
them so cheap he figured it wasn't worth the extra effort?

Probably because they lasted long enough in testing to finish typing the article?
I would not call $7 in smoked LED lighting worth the effort of rewiring a new string for 4 hours or repeated labor and parts.
The whole "warning" thing, to me, means he is not all that great with LED design.
("2 NiZn + 1 NiMH (recommended, with warning).  This gives you 2x1.7V + 1x1.2V = 4.6V, which is close to the 4.5V that your lights will expect")
That is not exactly practical, IMHO.

A proper voltage and resistor choice would be far more realistic to most people, IMHO.

You sure there is no cap in the AC lines feeding the bridge?
I personally don't like the design, but it could work.

You sure there is no cap on the bridge output?
I seem to recall it could cause epileptics to have a seizure, if the Hz was at their specific trigger frequency.
G-

[Norm]

There are cylinders at each end of these 110 ac LED lights look about the size of AAA battery
with a plastic coating....I jumped to the conclusion that they were resistors....they get slightly
warm......when I took them out of the box all in a cluster and plugged them in and moved them
they had a frequency flicker not quite as noticible as a strobe light.....(gad I hate them strobe lights)
  seem to recall it could cause epileptics to have a seizure yeah they could
maybe now that you mention it....I'll see if they charge or resist.
This set I have hooked with no resistors are 5 in a string they have been lit every night for about 6
hrs 40 LEDs and this tip top shape  NiCad 5 amp/hr 13.64  about 5 hrs. later down to 12.75
working for 3 nights like that but still would advise no one to try it this way unless they want to
gamble 7 bucks and about 3 hrs. labor and soldering and sealing about 20 joints. like I just did. I
just tinker and hope every thing works out....not really the best way to do thing IMO.
Norm.

[wooferhound]

You could use an LM317 as a Current Limiter and feed your LED arrays with almost any voltage.
http://www.reuk.co.uk/Using-The-LM317T-With-LED-Lighting.htm