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led lights getting dim if i turn on too many on one cable.how get full 12v if battery volts drop to 11v? Answered

I have a question a bit newbie type.First of all i dont have much knowledge about electronics but i know a bit.Actually i set up a solar system in my house and using it as 12VDC system rather then converting it to 220V. Now the problem is i m using 4 to 5  16watts 12VDC bulbs on single line and whenever i turn on 2 or 3 bulbs at once the bulbs got dim or if i turn on a 1amp 12vdc small fan the bulbs get more dim.As i understand this is due to voltage drop.My question how i prevent this or how i provide full 12v exact to all bulbs.I got quite powerful batery around 350 amps.Somemone told me that there are some cheap voltage regulators which do trick for me.Now i wnat to know which regulators provide 12v even if the battery voltage drop down to 11 or 11.5?
I hope that someone understand my problem and give me better solution to my problem.


Try looping back from the far end of your chain to the supply.


Get a step up converter that transform your 12 v battery level

to anything that is nominal mains alternative voltage in your place.

Personally i like the European 220 to 240 v 50hz

For you, it might be 110v 60hz ..Depends on what you can buy in your place.

Got no commercial with them, but seen it working well:

Google for sunpower us and they will have it

Then you will use normal house wirings( A lot cheaper and lighter wires), usual bulbs,

can plug anything you want !



Just to give some "insight" into the problem of power supply in 12V systems:
For a while I helped to retrofit old RV's and bigger caravans with new battery systems, lights, TV and all you would expect in your own home.
From the electrical side of things an oversized inverter was fitted first to allow the connection to mains supply where available.
I say inverter as these thigs actually worked like one or like a massive step down converter if you like.
They had a dedicated charging output for the battery too LOL
But the real pain started with the wiring of the 12V system.
If you ever had to use jumper cables to get an old diesel going in the winter times you know that thick cables are required and that the cheap supermarket ones won't even let it crank over.
Same was true for our retrofits.
First step was building the "loop hub".
Very flexible copper cables, as thick as my tumb were placed around the entire frame as a loop, so once around the end would go back onto the battery terminals.
In every location that required power above floor level a junction box was placed.
From these junction boxes slightly thinner cables ran up to the deiling or directly where needed, like for the TV and frigde backup.
Second step was to add more junction boxes for lights, outlets, switches and such.
Here the wires sizes were calculated by the boss but even for single LED lights we still used quite thick speaker wires (they are easy to handle and flexible).
Goal of the entire exercise was to have at least 11.2V volt reaching every point under nominal load.

If I translate all this into a standard home setup and assume a relative small home than already there is a massive problem with the wire lenght.
As already pointed out earlier in the topic voltage drop happens as a result of the internal resistance of the wires used.
As a result you also sometimes get what I call the "battery devil syndrome".
Everything seems to work just fine until you switch something on that uses a lot of power - in your car for example the high beam.
Electricity is like us, it prefer to go the way with the least resistance.
In complex setups this means switching a big load on can produce a bypass for the electricity if the resistance in the area with load is now overall lower than for example a tiny load 20m away on the other side of the system.
Now the juice prefers to go over the big load rather than all the way to the small load and in return the small one receives even less than expected.
Makes no real sense in theory or on paper but if you create complex enough you will sooner or later see the devil coming after you ;)
Just to kill some time I did some basic math to check what I would need to get most of my 12V to a load 30m away.
Turned out to be no fun once I realised for anything bigger than few LED's I require copper bars rather than wires LOL

Guess in todays times with high copper prices the only way out is to step up the voltage as high as possible and to step down for the loads.
If going up to 48V it should be possible to go with 10mm² cables for the supply lines feeding the rooms and speaker wire for LED lights from there on.
Bigger loads should get at least 4mm² wires.
This way one step down converter per room should suffice and be placed in a ventilated area with easy access in case it needs to be replaced later on.
Most step up/down converters of the cheap kind can only handle up to 30V but the wires like above should still be enough if you can accept some more loss along the way.

I had to deal with this situation a few times when fixing the installations of people without the right knowledge or trade certificates.
You already understand the cause of the problem and as suggested looping the supply is a way to fix it.
But feeding power from both ends will only help so much if the wire diameter is too thin.
Especially if you really need power the "little" voltage drop along the supply line is often enough to cause a lot of trouble.
In the cases where a replacement or adding another strand of cable was not possible I did a little dirty trick to fix the issue:
On the input side, meaning the output of your solar/battery system I added a step up converter that can handle 10 amps and is capable of providing up to 30V.
Crankied that one up to the max and added step down converters set to 11.5V wherever 12V was required for lights and such.
Real 12V devices like fans, tv's or fridges got a step down converter set to the full 12V.
The lower voltage for the lights is only to make sure they get the most lifespan ;)


That dirty trick is what every power company considers SOP when they step up 440 generators to 50KV on cross country transmission lines and step them down at the destination to usable lower voltages...

Hmmm i got it now but problem is the wiring is all around my house in all three floors and the distance between the source (Battery) to Load (Bulbs fans) is too much.Its approx 50 feet and its not possible to get separate wire for each bulb/fan from battery.As far as the thickness of wire is concern i installed the fattest available.I dont know much about the gauges or other things about the wires but only i know that its 150/76 wire.I used this wire from battery to each floor as parent wire and from that parent wire to Load (Bulb/fan) i use 100/76 and at some spots i use 40/76 for 1 or two watts LEDs.

Now as per u suggest first i have to convert my 12vDC to 30VDC via any regulator from battery and near load (Bulbs/fan) add another step down regulator and set it to 11.5VDC..This can be solution becaz i can convert my battery to 24VDC by connecting series and on load side i add stepdown 11.5VDC regulator but now question is that i have to add this step down regulator to each and every Bulb/fan or i have to add one step down regulator in parent wire in every floor?i dont have much knowledge about regulators can u please name any??Cheap and reliable.



Only real option is to have a step down converter right where you need the 12V, so basically for every single light.
If you go by floor level you still fight the losses from there to the end of the line.
Here is an example for a dirt cheap model rated for a max of 3A:


Quite simple really, just needs a multimeter to adjust the output voltage to your needs.


8 months ago

Another way of looking at it.

Standard 120 / 220 volts, a 4 volt drop is a 3.3% / 1.8% change (hardly noticeable) !

At low 12 volts, a 4 volt drop is a 33.3 % == 1/3 change and Very Noticeable !!!!


8 months ago

Your copper wire diameter needs to be 3 or 4 times thicker...

Or you should run a pair of separate wires to each from the battery.

I would bet you are using 16 gauge wire which has 1 ohm every 250 feet.

house runs are 500' to first outlet from the fuse box but you are using
two wires that makes a total run of 1000 feet of wire for a resistance
of 4 ohms..

Four ohms at 1 amp and you loose 4 volts down to 8v delivered..

diameter doubles every 3 AWG so double the diameter twice and run a 10
gauge wire with 1000 feet of wire is only 1 ohm and only loose 1 volt at
1Amp with 11v delivered to your load..

BTW 3 times thicker is 8 gauge which will deliver 11.5 volts...

Thanks for your reply.I really like that how to elaborate it technically but i m sorry i m not that good in all this but i understand a bit.I dont know much about gauges but all i know i used 150/76 wire as parent wire at each floor and 100/76 used from parent wire to Load Bulbs fans.Thicker wire means more cost and its not possibe to use more thicker wires for powering a few bulbs...May be i got it wrong.



You may be experiencing line losses. Wiring itself is a resistor, with a given leg resistance of (R per lines foot) * number of feet from source to load.

P= I*V


I = P/V

even with seemingly low per-foot resistance, 5*16/12 (6.7A) can turn into significant line losses.

If you intend to coniotnue operating five 16W lamps, I can think of only one practical solution. Use heavier gauge wire.