Need Help with Understanding And Changing a Circuit Diagram

[BillyBobJoeseph]

I am by NO means an electrical engineering student, so please explain it to me like I'm 5.
My friend sent me a circuit diagram and I don't know how it works/what it means, but basically I want to know if it's possible to charge 2 batteries at once instead of 1, using the same mechanism. If so, how would I?
Thanks!

 

[meBigGuy]

It's not even a complete diagram for charging 1 battery, much less 2.

What do you plan to connect as the "charging mechanism"?
What kind of batteries?
Is this a stand alone charger or do you have to charge while supplying power.

Describe a bit more about what you are actually trying to accomplish.

 

[BillyBobJoeseph]

Well, I'm trying to learn some circuit 101 here that applies to my project.
Basically, what type of voltage regulation and circuitry would I have to incorporate to charge not only 1 battery, but two. Both would be lithium ion but of different voltages.

 

[davenn]

here's some lithium-ion charger circuit ideas for you

http://www.bowdenshobbycircuits.info/page12.htm#lithium.gif
cheers
Dave

 

[sophiecentaur]

Charging batteries in parallel is not always a good idea and definitely not if they are different voltages. Lithium Ion are particularly fussy about the way they need to be charged. If you know as little as you claim then it could be dangerous for you to get involved. (That is not an overstatement.)
Charge one at a time or, preferably, use two different chargers which are suitable for each battery.

 

[BillyBobJoeseph]

Charging batteries in parallel is not always a good idea and definitely not if they are different voltages. Lithium Ion are particularly fussy about the way they need to be charged. If you know as little as you claim then it could be dangerous for you to get involved. (That is not an overstatement.)
Charge one at a time or, preferably, use two different chargers which are suitable for each battery.

I see. Couldn't I just use two separate voltage regulators so that voltage isn't a problem?

 

[davenn]

I see. Couldn't I just use two separate voltage regulators so that voltage isn't a problem?

no,
reread Sophiecentaur's second sentence ...

Lithium Ion are particularly fussy about the way they need to be charged.

which is why I posted the link to ideas, there were many other links on google
for Li-ion, Li-PO batteries, the voltage, current and timing of the charge all need to be considered

Dave

 

[meBigGuy]

Please read ANY article on Li-ion charging. It's hard to believe you even posted here without bothering to read the most fundamental information.

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

That's just for 1 battery. To charge multiple batteries you need to understand li-ion charge balancing.
https://en.wikipedia.org/wiki/Battery_balancing will get you started

 

[sophiecentaur]

two separate voltage regulators

A "Voltage Regulator" is NOT what you need, for charging Li (or many other types of) batteries. You can easily EXPLODE an Li battery if you don't treat it nicely.
What you are discussing, constitutes a dangerous practice. If you are not careful, the mods will close this thread.

 

[BillyBobJoeseph]

Understood.

 

[sophiecentaur]

But don't be put off by that. There is loads to say about the different charging methods for the various battery technologies.

 

[BillyBobJoeseph]

I was also wondering how multiple things could charge one battery (safely of course). Could I get some circuitry information on that too?

 

[sophiecentaur]

I was also wondering how multiple things could charge one battery (safely of course). Could I get some circuitry information on that too?

The way to approach this would be to use the different sources (wind, pedal, solar etc.) to combine in a single source - perhaps a large master-battery. That would buffer the variables in the source from the requirements of the battery to be charged. This is, of course, what the mains supply does all the time.

 

[BillyBobJoeseph]

The way to approach this would be to use the different sources (wind, pedal, solar etc.) to combine in a single source - perhaps a large master-battery. That would buffer the variables in the source from the requirements of the battery to be charged. This is, of course, what the mains supply does all the time.

What if I was using say, 3 solar panels and wanted to charge one large (lithium ion) battery? What circuitry would I need there? Each panel may gather different voltages, and I'm assuming as with before, Li-Ion are finicky so I'd need to do something different?

 

[sophiecentaur]

Are you assuming the panels are nominally the same voltage and that one may begetting more sun than the others? The characteristics of solar panels are not as straightforward as you might be assuming. This link shows a typical V/I characteristic and you can see that there is a big range of voltages as the device starts to hit its current output limit. This, I think, would imply that you could connect more than one panel in parallel (with a reverse protection diode in series with each) and they would settle down into sharing the currents according to the illuminance. This would not be the most efficient solution though. If you wanted the most out of such a system, you would need a switch mode regulator in each circuit. Certainly not a beginner's project. If the panels were cheap enough, you could point each one around the ecliptic plane and get a high voltage out at all times of day. But I think that would be an expensive solution, even though panels are dropping in price.

 

[meBigGuy]

Google "li-ion energy harvest"
Contrary to what others say, there are lots of solutions to choose from
IC's for energy harvest:
http://www.linear.com/product/LTC4071

This article explains the technology area you are in:
http://www.eetimes.com/document.asp?doc_id=1273070

This has pointers to reference documents:
http://www.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=3057&uiTemplateId=NODE_STRY_PGE_T

Here are some more references:
http://www.digikey.com/en/articles/...y-effectiveness-for-energy-harvesting-systems
http://www.digikey.com/en/articles/...ify-backup-power-in-energy-harvesting-designs
http://www.digikey.com/en/articles/...li-ion-battery-charging-for-energy-harvesting

One solution is to simply buy a board that charges LI-ion batteries from solar panels.
http://www.adafruit.com/products/390?gclid=CPL40bKiyMcCFYU5aQodb7wLGw (needs a 6V panel though)