Li-ion smart battery

[Makaram]

Hey guys, wanting to make a custom travel charger for my smart phone (galaxy s2 if relevant) and from I've been reading the phone has a smart battery.
So rather than requiring a smart charger, or some kind of current cut off in the charger itself, the battery does all the work???

is this correct because from what I've read on SMBus batteries is theres data communication to the charger yet the charger I currently have doesn't have data wires only +V and ground.

So is it safe to assume that if I supple 5v (the battery is 3.7v) that the battery will charge safely and not overcharge?

Is it possible that they tie the usb d+ and d- to bypass the safety cut off (cheap china charger)?


thanks for any assistance anyone can provide


Matt

 

[bountyhunter]

So is it safe to assume that if I supple 5v (the battery is 3.7v) that the battery will charge safely and not overcharge?

NO I would never assume that with an Li battery.

 

[Sceadwian]

Do you mean you want to make a charger for the phone? Typically the charge control circuitry is in the phone. If you're charging the battery outside of the phone then it may have saftey cutoffs but it can't control it's own charging, the phone has to do that.

What is typically called a phone charger nowdays is nothing of the sort, it's nothing more than a regulated 5 volt power supply.

If you're just trying to create a portable charger for the phone all that needs to be done is to use as large an external battery pack as you desire and feed it into a decent SEPIC converter to produce a regulated 5V output, the output needs to be nothing more complicated than the USB charging cord that the phone already uses.

Making one of these yourself is probably a waste of time, they're commercially available, and believe me they probably thought of a few more things than you did about what makes a good circuit =)

 

[Makaram]

thanks for the reply sceadwian.
Yes I could buy one but wheres the fun in that?! I'm more interested in the data communication of the battery but i think you've cleared that up for me thanks.