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Questions about power storage

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2V is very low.
you could use the solar cell to charge a single 1.2V Ni-Cad or Ni-MH cell.
It delivers 200mA only if it is at noon on the Sahara desert with the sun directly above. The current is less at other times and locations.
 
You can buy single cell lead acid batteries from RS Componenets but they need to be charged to 2.3V to be fully charged.
 
Peter_wadley said:
I see

Does anyone know about the lead acid batteries? Do i need a special circuit to charge them correctly?
There are a couple of ways to charge lead-acid batteries, depending upon their purpose.
If they are being used as standby power then the float charging method is preferred, thats is 2.25 to 2.3 volts per cell. (6V battery has three cells in series) and limit the charging current to C/10 (C=capacity in AH).
If they are used in the cyclic mode (charged and then discharged to a load) the charge voltage is 2.4 to 2.45 volts per cell, but monitoring the charge current and stopping the charge or stepping the charging voltage down to float charge level when the charging current reaches C/100.

If the float charging method is chosen the charger can remain connected to the battery indefinately without possible overcharge.
In the cyclic mode the battery can become overcharged and damaged if the charger is not removed or the charge voltage reduced when the battery is fully charged.

These are the general guidelines. I have built many lead-acid chargers and would be happy to offer more specific advise.
 
Peter_wadley said:
I'm just wondering if you need to reverse the polarity when you charge batteries..
That is how to blow up a battery. You do not charge a battery backwards.

do you connect the positive voltage to the cathode?
That is backwards.

do you have any charger schematics or kno of any tutorials?
In Google enter Battery Charger Circuit.

how do you limit the current? thanks
A current regulator circuit or a series resistor.
 
Here is a schematic of a lead-acid 12V float charger. With the schematic shown the current is limited to approximately 400Ma, and the yellow LED turns on bright when a 7AH battery is charged. If an accidental reverse polarity is connected to the battery a resetable fuse opens and prevents damage to the charger.
 
I forgot to up load the schematic. Here it is
 

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Hey thats great K7 thanks!

I have a ton of little questions Im wondering about .. endlessly :(


1) I am always wondering "Will those leads shock me?" ... is there a set voltage that electric shock will happen? What is the resistance of a human?

2) Why does high voltage cause larger sparks?

3) is it bad to short a capacitor?

4)When batteries are in series am I correct to think that the voltage increases and the current stay the same?

and like wise.. am I correct to think when batteries are parrallel.. voltage is the same (if batteries are the same) and current is increased?

5) I saw a small battery today that was 12v and 23A... I was wondering.. if some smarty put enough of these batteries in series .. and reached a high enough voltage ... what would happen if they where shocked from one hand to another .. would all 23 A go through there heart? could they die?

6) What do you think would happen if you shorted that 12v 23A battery?

7) I also saw some NiCd portable phone batteries rated at 3.6v and 3000mah.. (3 - 4 cells i think) could I use those batteries with 2v 200ma solar cell.. how would I make the charger .. how could I check if its charged ..

These are some of the questions that plague my brain almost all the time.

Hope someone can provide some answers :)

thanks
 
Peter_wadley said:
I am just wondering if you need to reverse the polarity when you charge batteries..

do you connect the positive voltage to the cathode?
ROFLO. :D

Think about it.

What happens when you connect two voltage sources in series?

They add.

What happens when the battery discharges?

Where does the current flow? For simplicity's sake think of current flow in turms of conventional flow, from the anode to cathode.

Now think of charging a battery.

Where does the current flow?

No offence intended but I think you neen to learn a bit more about ohm's law and current before you do this.

am always wondering "Will those leads shock me?" ... is there a set voltage that electric shock will happen? What is the resistance of a human?

There is no set voltage, it can vary enourmously depending on the thickness of your skin and how damp it is. Remember, it's current that shocks you not voltage, altough you can't have one without the other.

Sensitive parts of the body like the mouth can feel a tingle at less than 1VDC.

For dry thick skin you might only feel a tingle at voltages as high as 120VDC.

AC will shock you at far lower voltages than DC.

The IEE regulations state that in all live parts shall be insulated if their voltage exceeds 60VDC (ripple free) or 25VAC, in dry areas and 30VDC or 12VAC, in wet areas. I recommend you check the regulations for your area.

Generally, I avoid touching voltages greater than 12VAC or 30VDC as I often have sweaty fingers.:D
 
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