Getting the electricity to where I want it

Thread Starter

zemanekj

Joined Jan 31, 2019
38
As you can see from the picture that I've uploaded I have two DC power sources powering one light bulb. However, the 2V power source isn't getting to the light bulb because the 24V power source is channeling it's current into the light bulb, and the 2V battery. So my question is how do I get the 24 volts to only go into the light bulb, and not block the 2 volts?
 

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AlbertHall

Joined Jun 4, 2014
8,358
Disconnect the 2V battery. As it's a 24V bulb there's no point in feeding it with 2V.
 

dendad

Joined Feb 20, 2016
3,002
See my comment on your earlier post referring to water tanks.
In this case, the 24V "tank" will try to fill the 2V "tank" to equal pressure, and as it is a battery, probably explode it.
Not good practice ;)
And as AlbertHall points out, a 24V lamp will not run on 2V.
 

Thread Starter

zemanekj

Joined Jan 31, 2019
38
See my comment on your earlier post referring to water tanks.
In this case, the 24V "tank" will try to fill the 2V "tank" to equal pressure, and as it is a battery, probably explode it.
Not good practice ;)
And as AlbertHall points out, a 24V lamp will not run on 2V.
But isn't the 2 volt battery already at it's "max pressure" sense it's designed to hold just 2 volts.
 

Ylli

Joined Nov 13, 2015
776
That makes no sense. Are you trying to provide 2 volts to the load when the 24 volts is disconnected? Then you will probably need to use a relay such that the 24 v coil is connected to the 24 volts source and the 2 volts is fed through the NC contacts. That way when the 24 volts is available, the relay pulls in and disconnects the 2 volt source. When the 24 volts is removed, the relay drops out and the 2 volts is supplied to the load.

If the load can accept 1.3 volts instead of 2 volts, you could do it with a single diode. If not, then you would need the relay.
 

dendad

Joined Feb 20, 2016
3,002
I'm trying to get the 24 volts to only go into the light bulb, and not block the 2 volts.
What is the 2V anyway? Is it a 2V battery? And why do you have it?
You need to explain what you are trying to do in a bit more detail as so far, it makes no sense at all, so it is very hard to help you.
 

dendad

Joined Feb 20, 2016
3,002
But isn't the 2 volt battery already at it's "max pressure" sense it's designed to hold just 2 volts.
Not really. In fact, a lot of fires are started by overcharging batteries. Some chemistries are more forgiving that others, but all batteries will be damages by overcharging. Back to the water, think of it as splitting the tank by over pressure. But usually a lot hotter!

If you have the time...
https://batteryuniversity.com/learn/
 

AnalogKid

Joined Aug 1, 2013
8,103
Why do you want a 24 V battery connected *in any way* to a 2 V battery? You still have not told us what it is you are trying to achieve. If you impress 24 V across a 2 V battery, the battery will fail. Depending on its chemistry, it might burst into flame. Really.

If you goal is for the 2 V battery to power the LED only if the 24 V battery is disconnected, it won't. Any lighting system designed to run on 24 V will either not light up, or just barely glow on 2 V.

ak
 

Reloadron

Joined Jan 15, 2015
4,508
As drawn I see the + of the first battery going to the - of the second battery and the + of the second battery going back to the - of the first battery? Discounting the lamp all I am seeing is two batteries in series which are shorted out. I see a 26 volt short? What am I missing here?

Battery Short.png

Ron
 

djsfantasi

Joined Apr 11, 2010
5,591
As drawn I see the + of the first battery going to the - of the second battery and the + of the second battery going back to the - of the first battery? Discounting the lamp all I am seeing is two batteries in series which are shorted out.

View attachment 169360

Ron
So wait, are you saying that the 2V will never go anywhere, because everything will short out. And soon provide 0V? *wink wink*
 

Reloadron

Joined Jan 15, 2015
4,508
So wait, are you saying that the 2V will never go anywhere, because everything will short out. And soon provide 0V? *wink wink*
Well as I see it those batteries are having a really bad day. The only survivor will likely be the lamp and I am not sure about that.

Now if the thread starter can better explain his goal I am sure there is a solution but as it is about now I haven't a clue what this circuit should be doing?

Uh Oh, now I see this thread and a few responses in this thread make sense. This is where multiple threads can be confusing.

Ron
 

WBahn

Joined Mar 31, 2012
24,692
I'm trying to get the 24 volts to only go into the light bulb, and not block the 2 volts.
Not block the 2 V from WHAT? Why is there even a 2 V source there? In that circuit the 2 V serves NO purpose. You want the 24 V to go to the bulb and not the 2 V. Fine. Remove the 2 V source. Or put a diode in it with the anode connected to the positive terminal of the battery. But why not just remove the 2 V source?

Again -- stop trying to get people to help you kludge together some solution you have in mind and instead describe your actual problem so that people can help you solve your actual problem.
 

WBahn

Joined Mar 31, 2012
24,692
Well as I see it those batteries are having a really bad day. The only survivor will likely be the lamp and I am not sure about that.

Now if the thread starter can better explain his goal I am sure there is a solution but as it is about now I haven't a clue what this circuit should be doing?

Uh Oh, now I see this thread and a few responses in this thread make sense. This is where multiple threads can be confusing.

Ron
Agreed. Once again we see someone trying to force some notion of a solution to a problem who won't describe the problem they are trying to solve. Instead, when it becomes clear that no one can help them, instead of providing useful information, they basically just start another thread asking essentially the same thing with no more information than before.
 

Tonyr1084

Joined Sep 24, 2015
3,578
Batteries in series will either add to or subtract from the voltage. Batteries in parallel will try to equalize each other. In your case, a 24 volt battery in parallel with a 2 volt battery will result in high current overcharging of the smaller battery, leading to excessive heat and potential explosion. Not being overly dramatic here - but your circuit is one that can not work. You say the lamp is an LED - OK, I've taken creative license and pointed the LED in the direction of the 24 volt battery. In this example, two issues exist (ignoring the 2 volt battery for the moment): First, there is no resistor to limit the current to the LED. But let's assume the battery is current limited and will not harm the LED. The second issue IS the 2 volt battery. You state that it you're not seeing 2 volts at the LED. That's because the LED is reverse biased against the 2 volt battery. So if we now ignore the presence of the 24 volt battery (and lack of resistors) the LED will not light because it's in backwards. IF you reverse the LED then the 24 volt battery will do nothing for the LED and only the 2 volt LED will have any current flowing through it. But lets not ignore the presence of the two batteries of extremely differing voltages. The current from the 24 volt battery will cook the 2 volt battery. As the smaller battery fails it may draw excessive amounts of current from the big battery and potentially damage that as well.

I have one question for you: IS THIS HOMEWORK?

ZZZ Batteries.jpg
 

Tonyr1084

Joined Sep 24, 2015
3,578
Batteries in series will either add to or subtract from the voltage. Batteries in parallel will try to equalize each other. In your case, a 24 volt battery in parallel with a 2 volt battery will result in high current overcharging of the smaller battery, leading to excessive heat and potential explosion. Not being overly dramatic here - but your circuit is one that can not work.
EDIT - yes, they're in series. My bad! I think my point was supposed to be that they were shorted. Got a little off track with that.

So, in retrospect: The 2 volt battery is in parallel with the LED - assuming I've drawn the LED the way the TS intended. Not sure exactly how that circuit would respond.

Here's an updated schematic of the circuit in question: Again, resistors notwithstanding.

ZZ Series.jpg
 
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