Instructables
This instructable will show you how to make your own solar battery charger from very simple components. It is taken from my documentation provided with a kit I supply - you should easily be able to source the same components yourself of course.

If you have any comments on how to improve the documentation then please do not hesitate to say :)

http://stores.ebay.co.uk/Electronic-Widgets-Inc

 
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Step 1: The Components Needed

The items shown in the image are contained in your kit. This page explains their uses. Your kit may have a smaller/larger copper stripboard than this and may contain extra wire - I try to beef up the kit as time goes on.

The Copper Stripboard contains rows of copper tracks. Each track is electrically separate from its neighbour. It contains holes for your components. The boards I supply are larger than needed, this will allow you to expand the system at some future date.

The Batter Holder ... errrr holds your batteries.... and comes with two pins, one for the positive and one for the negative ends, they will be soldered into the stripboard.

100 Ohm resister - at one point this was needful in the kit as the LED couldn't cope with some of the voltages in the experiments - however the new LEDs do and the resistor is simply in there because it is advertised as such! Maybe you will have need of it when you expand the system.

LED - this is a high intensity light emitting diode. 3.2-3.6V forward voltage, with 10000mcd at 20ma. A LED must be placed in the circuit the correct way around. The longer leg should receive current from the positive terminal/direction.

1N5817 DIODE - this diode allows current to flow in only one direction - this prevents battery power discharging through the solar panel at night. It drops about 0.2V from the system. This blocking diode also needs placing in the circuit in the correct orientation. The diode has a circular band across its barrel at one end of the diode. This should be closest to the negative/ground.

Wires - Usually I include at least 4 wires - a black and red wire for the solar panel, a brown wire as a jumper and another wire for use in unsoldered testing.

Solar Panel - This image shows the back of the solar panel. On your solar panel in the centre of the left side and the right side you will see a small panel of smooth metal - this is the negative/positive terminals. I have marked the positive side by adding black dots on that side. This solar panel will output a max of 3V at 150ma.

Warning - I suggest you read the whole document before making any experiments - information is contained throughout the document which will improve your understanding of charging batteries using solar power.

HINT - you should probably purchase a multimeter and learn how to use it - this will tell you important information on typical voltages and currents you solar panel will produce in varying weather situations.

Soldering

It is quite possible to use this kit without having to do any soldering at all - however at some point you will need to so I include both soldered and non soldered options.

http://www.kpsec.freeuk.com/solder.htm is a good site explaining soldering.
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KosherAnt12 days ago
can you do or share a link to one with a battery charger indicator and two USB ports as well
jimmysymo2 months ago

I have been using Solar panel 3.5 volt 400mA to recharge 2 ,1.5volt batteries and run up to 3 leds in my instuctable (Bronze steampunk solar light) I used an old solar garden light (broken) and used the circuit inside instead of a diode.Now I bought 5 new diodes and didn't know where to put it .today I found your (instuct"

and was very impressed with your explaining and now understand much more.

(SEE even at the age of 70+one can learn more .thanks Zvi..(JIMMY)

Keohohina3 years ago
Thanks this has really helped, Im trying tho get a pair of solar panels which are the same size as yours to power a water pump and charge a battery at the same time. Any suggestions
DerDok Keohohina2 months ago

Hi

Keohohina, did you ever get a answer to your post?

I'm trying to build one
that powers a fan for a dehydrator and also charges the Ni-cad batteries
for it and I'm running into snags. I'd like it all to be real simple, something I can build cheap, maybe with the stuff in my junk pile, but also have overcharge protection and an indecator that its charged. Looked all over the internet, cant seem to find what I want. How did you fare?

sjs23 months ago

Hai

i want to make solar charger to charge two batteries simultaneously of the spec

Voltage
: 14.8V

Capacity : 5400
mAh

how many solar cells would be required , the circuitry and the weight of the total set including the solar pannels

thanks


miguipda4 months ago

Hi,

some basic questions :

1) how to calculate the resister and diode value in regard of the Watts (solar panel). It means when we buy a 10W or a 30W or 60W how could we know (calculate) the best resister and diode to also buy ?

2) how to calculate the good battery to buy following the panel we choosed ? By example if we buy 4 panels of 3 watts that we will put in serie (or in parallel) how could we be sure to buy the best battery ?

Sincerely thanks ;-)

Pizzaenfeu4 months ago

Could I have another link to buy a little kit as shown? Or better that's not too expensive? The shop linked up is deleted :/

I'm using three dollar store yard light panels and I was wondering if a Zener diode would work. I have one in my junk box. 20V, Pd 1W. Will this fly?

I'm building an AA and AAA battery charger.

How can i use 4V 100ma Solar panel in the above manner?
jemor1433 years ago
Can the 1N5817 diode be use with a 6v solar panel (130mah) to charge 4 AA?
According to this Data Sheet, it appears to be a viable, if not over-kill type use. Is there any specific reason for using a Schottky Barrier Rectifier diode?
krishnan1112 years ago
we can charge all types of battery?? ni-cd ,ni-pb or li-on batterirs??
No, if the battery doesn't have "rechargeable" on the outside (excluding the OLD style carbon rod batteries), then they are not rechargeable and will leak or explode of put in a charger for any length of time.
An improvement: add a LED with no resistor in series with the positive line on the solar panel to the battery holder. It will serve as a current limiter and a basic display as to how the battery is charging
eg. Brightly lit = charging battery a lot
Not so bright = charging more gently
dim = trickle charge

Also *USE A RED OR YELLOW LED FOR CHARGING SMALL BATTERIES OFF A SMALL PANEL*
Just my ten cents :)
Uber
TechKid673 years ago
Hi, I am new to solar energy and am trying to create an emergency power light kit. In my prototype I want a solar panel to charge somewhere around 10 LEDs. First off: Is this possible if they are aligned in parallel? Second: Is it possible to over charge the batteries and if so (which would probably have a horrific outcome) how can I prevent that? Third: How might I go about getting the solar panel to charge a large re-chargeable battery which then charges the smaller batteries. I want to do this so the suitcase doesn't need to be left in the sun in order to charge the batteries. If you can't help me with any of this its alright but thank you for any information you can provide. If some of this didn't make sense please send me an e-mail and I'll try and make it more understandable
Ryanclark@verizon.net
kylengineer3 years ago
i found this very helpful.thanks but i ddnt gt to see the complete circuit with all the components listed from the start,i only saw piece by piece.i would like to see the whole complete circuit.
Hi
I am making solar panel jacket. In order to charge phones and i-phones etc
I need some help with circuit. do not know what cicuit to use.

Please help
rcisneros4 years ago
Question. What happens if the solar cells aren't the same? Or one solar cell goes into shade before the other? So you could end up with a cell pumping out let's say 2v @ 20mA and the other 5v @ 100mA. Would they just add up to a 120mA output ? Wouldn't the flow change direction and head into the 2v 20mA cell?
rcisneros4 years ago
Question. What happens if the solar cells aren't the same? Or one solar cell goes into shade before the other? So you could end up with a cell pumping out let's say 1v @ 20mA and the other 3v @ 100mA. Would they still just add up to a 4v output ? or You could have a cell pumping out let's say 1v @ 100mA and the other 3v @ 20mA. Would they still just add up to a 4v output?
mdelzo4 years ago
what happens if i get a solar panel of 4V and I have 4 AA batteries in series. would it charge?or go the opposite way? tks :)
No, you need a higher voltage panel to charge 4 AA's in series. Here at Sundancesolar.com we recommend at least 6V to charge 4 batteries.
rtyu4 years ago
thank you
pure energy
popa272724 years ago
i was playing around with my solar powered radio once and noticed that i got less static and the battery charged better when i focused a magnifying lens over it to the point where the solar panel appears at its largest,

just a simple way to increase efficiency of the panel
kroq-gar784 years ago
what is the voltage & current required for the solar cell?
mrziggy50006 years ago
Does any one know how many battries i could charge with a solar panel 1.5V at 500mA
If you are trying to charge a 1.25 volt battery (which is the typical voltage of a rechargeable battery in size AAA, AA, C, or D), then you can charge ONE battery with a solar panel that has 1.5V at 500mA. Be very careful when you charge your battery because 500mA is 5 amps, and that is a lot of amperage for a 1.25 volt battery. You are in serious danger of overcharging and making your battery leak or explode. Some of the fast chargers in the stores charge at a very fast rate (800mA), but if you decide to charge your battery using the 500mA straight from your solar panel you will have to monitor your battery very carefully and check it at least each hour to make sure it isn't over charging.If you want to make it slower and easier, you will need to add a resistor to take the amperage down to a decent level of about 100-200mA. There are websites you can use to calculate what resistor you need. Try googling "ohms law calculator" or "resistance calculator." Good luck!
500 milliamps is point 5 (.5) amps. one amp is 1000 milliamps. just like 1000 mililiters is one liter. 500 mA is still a lot, and may overheat the battery, but it is not as dangerous as you put in your comment. just dont stick it to your tounge, 60 miliamps is enough to kill you (stop your heart) but i have been electricuted with 15 amp ac line like 3 times, and i cant even count how many more than 60 miliamp dc lines! and obvously im alive, so i think the point of death is more like 20 amps.

Can you reconcile "60 miliamps is enough to kill you" with "i think the point of death is more like 20 amps"?

Your statement is partially incorrect. 500mA is not 5 amps, it is 1/2 amp. mA stands for milliamps. Milli stands for thousand (even though you would expect it to stand for million). 5,000mA is 5 amps. I know nothing else about charging batteries, but I hope this helps! :) I need to find a way to reliably and safely charge a 7.2volt 40mAh (yes, forty, not four hundred, it's a small pack) Ni-MH battery pack without supervision. Any suggestions? DC
Oh. and BTW....

If you charge your battery at a higher amperage, you won't be in danger of making the battery explode unless you overcharge it. You will get a good solid charge no matter how many amps you put into it. The disadvantage to using higher Amps is that you won't get the "trickle charge" effect that makes the battery very full to the brim. So, if you go above the 40mA, it won't hurt your battery. I purchased some solar panels at www.sundancesolar.com that charge at a rate of 50mA. You can see my tutorial with all of the links you need to buy the stuff here.here. I haven't posted it on instructables yet....I just wired 3 panels in series so I have a total voltage higher than the combined voltage of the battery packs. Sadly, I don't think there is a way to charge any Ni-Mh battery pack without some supervision. The slower you go the less likely you are to overcharge because you can check it more often. Good luck!
Oh yah...and thanks for correcting my math...i always forget to add or subtract the zeros....and when I say it won't hurt your battery to go over its rated 40mA, I don't mean flood it with over 4000mA all at once. :) You should safely be able to charge it with 100-200mA, or more...depending on how thorough and deep you want the charge to absorb into your battery. Recharging with higher mA will result in a more shallow charge (that is if N-Mh batteries respond like lead acid batteries to recharging). I hope this is making sense. Let me put it this way. Lower charge rates result in fuller batteries with a strong charge. High charge rates give your battery a burst of energy that will charge the battery but not to its full capacity. Thats why charge controllers are needed when trying to charge a lead acid battery to its peak efficiency. It varies the rate of current to compensate for the charge rates needed to completely fill the battery to full. Again, this is all based on the assumption that Ni-Mh batteries behave like lead acid batteries when recharging.
So I could safely connect a 12v7aH battery to a 10 amp "automatic" car battery charger and leave it overnight? How about the same 12v 10a charge on a 12v38aH battery? And what the heck does it mean if a battery says something like 7aH/20Hrs??
NO! You will damage it! Charge it with about 1 amp so it gets a nice trickle charge.
As far as I can tell you are asking if its okay to connect a 12volt battery to an automatic car battery charger? I think it will be fine because as far as i know the "automatic" car battery chargers will do an auto shut down when the battery is full. I haven't used one, so you better make sure that it has the auto shut down mode before you leave it overnight. I think a 12V battery is fully charged when its voltage is at 13.2 volts, so in theory your automatic battery charger should be able to detect when that voltage has been reached and then stop charging the battery.

7aH means that you can use the 12 V battery for 7 hours at 1 amp current rate or at 7amps for 1 hour. A 38aH battery means you can use the battery at 1 amp current rate for 38 hours or 38 amps for one hour.

If you increase or decrease the current to more or less than one amp, then the battery life will change accordingly. Pulling less current than 1amp per hour will make your battery power last longer so it will get more than the rated 7 hours or 38 hours of life.
does that happen to be a rc(helicopter/plane?) battery?
No, it's actually a laptop Cmos battery pack.
K, I know that a lot RC battery packs(including mine) are 7.2v
Wrong... 500mA = .5A and 500dA = 5A. m = three decimal places, d = two decimal places
It might be different if you put the batteries in parallel, then you could put as many as you want on the circuit. Of course that would up your current a lot though.
is it possible to charge a cellphone or a mp3/mp4? please kindly answer
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