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Topic: Monitoring and Charging Multiple Batteries (Read 2 times) previous topic - next topic

Cerin


Are you using anything like a solar charger shield? Can those use an arbitrary external power source instead of a solar panel to recharge the battery?


That shield is designed specifically for a single cell lithium battery. Can't change the output voltage.

To charge a lead acid battery a ready made solution would be called an "on board battery charger" (example). In real world use they are designed to stay permanently attached to a car/boat and then plugged in to a wall socket to maintain the battery.

For a non-ready-made solution I'd look at something like a UC3906. Lots of examples from Mr. Google on this.


Thanks, but I was referring to the *input* source, not the output. e.g. charging the single lithium from a wall supply instead of a solar panel. If it expects a certain voltage/amperage from the solar panel, what would be the problem in getting that instead from a wall adapter?

Cerin

Would it be feasible to hook up the load outputs (not the battery hookups!) of two 3.7 USB Lipo chargers (e.g. this or this) in series to effectively get a 6-7V rechargeable Lipo power supply?

0AlphaOmega

#12
Jan 19, 2013, 12:03 am Last Edit: Jan 19, 2013, 10:22 am by 0AlphaOmega Reason: 1
I'm really not up on LiPo, but then nor is Boeing  :smiley-eek:

I understand that individual cells within a pack need to be charged individually, and that one should not charge cells that have dropped below a certain voltage, nor mix cells of differing voltages. But I read that a long time ago and it may not apply to current cells. (something else to do!)

Edit
This looks readable http://www.rcgroups.com/forums/showthread.php?t=209187

Edit, Edit
Mmmmm, quite old "Winter 2005"  But worth a read, Check out the lower end of the post if you want to be put off.

I've had a look around for home-brew chargers, but not found any I'd recommend, but there are many low price units out there (if you have a multi pack, get a balance charger). As with NiCd's it's the RC peeps who are pushing with LiPo so go read their forums.

Many years ago I used to make fast NiCd chargers for RC clubs, I always supplied them with metal charging cages due to the possibilities of explosion & fire!

It looks like the first part of your project will be a battery management system... Something for your Masters degree ;) Then you can get a job with Boeing - even the big boys get it wrong.

For whom does the clock pulse? It pulses for you!

0AlphaOmega

Quote
Thanks, but I was referring to the *input* source, not the output. e.g. charging the single lithium from a wall supply instead of a solar panel. If it expects a certain voltage/amperage from the solar panel, what would be the problem in getting that instead from a wall adapter?


Ebay, buy a handful of these...

search for "Converter Step Down Module LM2596"  cheaper than chips! No really, you can't buy the parts for the money.

Obviously you will need your wallwart to be able to supply enough current, so you need to know the C rate (current) that you will charge at (always over specify as wallwarts are usually poorly regulated and over optimistic when quoting current, you don't want another source of fire or failure.

AC wallwarts may be better for you, but remember that after rectifying & smoothing, your voltage will increase by root 2 (about 1.4 times) So bare this in mind when specifying your voltage regulator.
For whom does the clock pulse? It pulses for you!

techmind

You can use a tl431 and a P-mosfet as lowvoltage detector and shutdown controller, i made a LiIon hack for my bosch powertool: http://techmind.dk/elektronik/under-spaendings-detektor-med-tl431-bruges-til-hack-af-bosch-skruemaskine-med-li-ion-batterier/

I Just connect a standard cheap RC multi charger like this:  http://techmind.dk/tilbeh%C3%B8r/multilader-fundet-pa-ebay-co-uk/

Also, there are IC able to handle multible batterier. A great arduino project could be to make a LiIon/LiPo charger for 20 x cells ;)
Why not convert the world to run on electricity :)

http://techmind.dk

Blog is in Danish, use google translate please

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