Weird christmas lights problem

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Weird christmas lights problem

mdav056

607 posts

Ultimate Geek

Subscriber

#243389 9-Dec-2018 20:29

A few months ago I purchased a 50 m length of LED lights, solar type, from Mitre-10. I just strung them up (took me ages...) and they have an odd problem: the first 5 m of the lights run fine, then the next 20 m don't light at all, and … the last 25 m (I think that adds up right) light up fine. There are 3 wires, but nothing appears to change about which ones are connected at the points at which they go on, and go off. I know they will all be connected in parallel, so one failed LED won't affect the others.

Now I do know how to fix the problem (sigh, take them down and take them back), but I'm wondering why they are acting like this. Can any of you help me understand?

gml

Aredwood

3885 posts

Uber Geek

#2142238 9-Dec-2018 21:07

They will probably be wired in groups, in a series / parallel configuration. As LEDs are terrible at sharing current evenly, if you try to wire them in a pure parallel configuration. So you probably have some faults in some of the series sub strings.

mdav056

607 posts

Ultimate Geek

Subscriber

#2142249 9-Dec-2018 21:59

Ah, thanks, Aredwood, understand now

gml

richms

28168 posts

Uber Geek

Trusted

Lifetime subscriber

#2142261 9-Dec-2018 22:31

Probably made wrong and have some in the reverse polarity.

Is the 3 wires to give them 2 different channels to allow for chasing effects or just taking one of the feeds to the other end to make them more evenly bright?

The solar ones are almost all just in parallel along the whole string as blue LEDs have quite a wide voltage swing over the range where they conduct so can parallel up pretty well, not like the old red ones that would suddenly overcurrent once you were past 1.7 volts over them.

Richard rich.ms

Fred99

13684 posts

Uber Geek

#2142265 9-Dec-2018 23:10

Were they these ones - not flickering as expected?

elpenguino

3419 posts

Uber Geek

#2146747 17-Dec-2018 23:22

Wow, that 'L'' and 'i' run together and look like a 'u' which makes the box very attention getting.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

richms

28168 posts

Uber Geek

Trusted

Lifetime subscriber

#2146750 17-Dec-2018 23:41

Richard rich.ms

kiwifidget

"Cookie"
3415 posts

Uber Geek

Lifetime subscriber

#2146821 18-Dec-2018 08:16

Rule#1 with xmas lights - test them before putting them up.

Delete cookies?! Are you insane?!

Equinox IT

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.

xpd

Geek @ Coastguard NZ
13765 posts

Uber Geek

Retired Mod

ID Verified

Trusted

Lifetime subscriber

#2146822 18-Dec-2018 08:21

I just ordered a 20m run of LED lights that are powered via USB..... good old TradeMe ;)

Wonder how long they'll last......

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

LinkTree

xcon

147 posts

Master Geek

ID Verified

#2146825 18-Dec-2018 08:35

I bought these from AliExpress - 30m lengths powered by a 12v computer power supply
They are on the side retain wall /fence , been outside for few months now so far surviving the elements

mdav056

607 posts

Ultimate Geek

Subscriber

#2146942 18-Dec-2018 10:14

kiwifidget:

Rule#1 with xmas lights - test them before putting them up.

Yes. Life is for learning. Rule 0 is, try them in the shop. But, I'll need a portable sun. I'll try aliexpress.

gml

xpd

Geek @ Coastguard NZ
13765 posts

Uber Geek

Retired Mod

ID Verified

Trusted

Lifetime subscriber

#2146944 18-Dec-2018 10:19

I went for USB ones because I find solar powered ones generally die after a while - altho, the ones we just removed, did last for about 3 years. Wife dosent like having things plugged in all the time for power, so my good powerbank will be put to use for these lights during parties etc.

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

LinkTree

frankv

5680 posts

Uber Geek

Lifetime subscriber

#2147074 18-Dec-2018 13:12

xpd:

Wonder how long they'll last......

Maybe it's just me, but it's the putting up and taking down of Xmas lights that causes the failures. Lights that are left up all year round last much longer.

esawers

551 posts

Ultimate Geek

#2147087 18-Dec-2018 13:28

We bought the same set from Mitre10, the first set we tested, spent 2 hours stringing them around our tree.. and they didn't work.

Took them back and got another set and the same thing happened.

Turns out we had clipped the wire that runs from the lights to the solar panel under something, enough to stop them working at all.

As soon as I took the solar panel down they worked fine again.

MikeAqua

7773 posts

Uber Geek

#2147149 18-Dec-2018 14:54

mdav056:

Yes. Life is for learning. Rule 0 is, try them in the shop. But, I'll need a portable sun. I'll try aliexpress.

If you bought them from M10 why not take them back. Even if you don't have a receipt they can search by the card you paid with and generate the receipt. I did that few months back for an irrigation timer.

Mike