Sold/Expired Sales Thread: USB Micro Charger for Li-Ion/Poly Cells

[donn_]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Just in case you're running out of ideas, how about a unit which includes a single 123 bay with a USB connector. A rigid unit which plugs into the USB port, with no exposed wires, clips or magnets.

I could use it in Li-Ion and LiFePO4, or both in one unit, with a selector switch.

The Li-Ion model could be used with cells smaller than RCR123 as well, with spacers.

I could get rid of most of my Nano chargers.

 

[wapkil]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Heh, I was trying to find some time to make a similar charger for myself

I would probably be in for one but I have a question - what IC it uses? I tried but couldn't find this information in the Chimera thread...

As a power supply one can also use a small power adapter with USB output - many of them are rated around 1A (e.g. this one). The current in reality may be lower, like 800-900mA, but it's still more than a computer USB.

 

[Sabrewolf]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Heh, I was trying to find some time to make a similar charger for myself

I would probably be in for one but I have a question - what IC it uses? I tried but couldn't find this information in the Chimera thread...

As a power supply one can also use a small power adapter with USB output - many of them are rated around 1A (e.g. this one). The current in reality may be lower, like 800-900mA, but it's still more than a computer USB.

here ya go:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MAX1555EZK+T-ND
I get them from another supplier though

 

[Sabrewolf]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Just in case you're running out of ideas, how about a unit which includes a single 123 bay with a USB connector. A rigid unit which plugs into the USB port, with no exposed wires, clips or magnets.

I could use it in Li-Ion and LiFePO4, or both in one unit, with a selector switch.

The Li-Ion model could be used with cells smaller than RCR123 as well, with spacers.

I could get rid of most of my Nano chargers.

That is on my list... :thinking:

 

[Edwood]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Strain Relief:

I'd recommend 5:1 or even 4:1 heat shrink, so you can cover most of the metal part, so that the part that plugs in is only exposed. That way, it greatly reduces accidentally shorting on the outer metal casing with a wayward magnet.

Would also make it look nicer and offer even more strain relief. It would be a continuous heat shrink sleeve that would cover the metal part, all the way up to the wire (where you already have the smaller heat shrink strain relief.

Either way, I'm in for one. Two if you use 5:1 or 4:1 heatshrink.

-Ed

 

[Norm]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

A 100 mA version would be a good for charging 14250s, 10180s etc.
Norm

 

[Sabrewolf]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

I'd recommend 5:1 or even 4:1 heat shrink, so you can cover most of the metal part, so that the part that plugs in is only exposed. That way, it greatly reduces accidentally shorting on the outer metal casing with a wayward magnet.

Would also make it look nicer and offer even more strain relief. It would be a continuous heat shrink sleeve that would cover the metal part, all the way up to the wire (where you already have the smaller heat shrink strain relief.

Either way, I'm in for one. Two if you use 5:1 or 4:1 heatshrink.

-Ed

The charger Does have short-circuit protection anyways
I do plan on covering most of the plug with heatshrink
The stuff i use is an industrial grade, 3:1 ratio Adhesive-Lined :thumbsup:
I could use the 4 or 5:1, But i like the adhesive lined stuffs better.
It has much better tear resistance and holds up lots better :nana:

A 100 mA version would be a good for charging 14250s, 10180s etc.
Norm

That version is in the cards too :thumbsup: The same charging chip does
300mA and 100mA charge rates. I dont really have enough room
inside the housing for a switch to alternate between the two.
So there will be 2 versions available.

 

[gma]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

I would be in for one. Thanks!

 

[greenLED]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

Pricing would be about 35$ meethinks
I would need about 10 people to start this little project

Any Takers?

Heck yeah!! A truly portable li-ion charger... :rock:

Sign me up, please.

 

[Illum]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

that looks deceptively simple, wonder why my DSD charger takes up all that space with a big fat PCB board under the battery holder :thinking:

 

[csshih]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

that looks deceptively simple, wonder why my DSD charger takes up all that space with a big fat PCB board under the battery holder :thinking:

because 120v/220v is much harder to convert to 3.7..... than 5v...
if you find the actual charging circuit.. there isn't really that much..


110V AC OR 220V AC --> 3.7V DC
compared to 5V DC--> 3.7V DC

 

[wapkil]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

here ya go:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MAX1555EZK+T-ND
I get them from another supplier though

Thanks. Can I unsolder the DC pin to change the 280mA output to 100mA output? Or is the USB pin unconnected so I would have to connect it also?

I'm not sure yet which output would be more useful for me, and I'm thinking how to get both in one device

 

[wapkil]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

that looks deceptively simple, wonder why my DSD charger takes up all that space with a big fat PCB board under the battery holder :thinking:

because 120v/220v is much harder to convert to 3.7..... than 5v...
if you find the actual charging circuit.. there isn't really that much..

The second reason is the price. For Chinese manufacturers producing this big fat PCB board with a few simple components is cheaper than buying one small IC that Sabrewolf uses.

EDIT: It means that almost always in these chargers there is no charging circuit to be found. The charging is done by a few of these cheaper components working together.

 

[barkingmad]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

A LiFEPO4 version (charging to 3.6v) would be great...?

 

[Sabrewolf]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

A LiFEPO4 version (charging to 3.6v) would be great...?

I did cover that a buncha posts ago...
It is in the works But i need a dedicated
charging IC to do that. And the only one i
can find is on back-order till late october :thinking:

 

[Sabrewolf]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

I was getting questions about a Constant-Current output on this charger:

Its the chart on the left. Does that not mean constant current?
This is a regulated charging IC, Not a goofy Diode-Based one you
get from Dealextreme.. (i can show you some scary pics of that)

 

[wapkil]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

I was getting questions about a Constant-Current output on this charger:

Its the chart on the left. Does that not mean constant current?

One of these questions was mine

Yes, I think this chart means that the charger uses the correct CC/CV method (plus a pre-charge if the battery is initially overdischarged). It's strange that Maxim doesn't explicitly write in the data sheet that it uses CC/CV - they write it for other ICs. This and the lack of the charge profile (in time) graph is what fooled me.

Thanks for the answer.

EDIT: The correct charging algorithm and the regulation voltage (i.e. the battery voltage when it finishes charging) better than achievable with cheap components in non-integrated chargers, indeed makes it better than most of the competition. Actually it makes it simply work correctly but even this is quite rare nowadays.

 

[Thujone]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

I would be interested in one. If possible I would prefer no clips just magnets soldered onto the leads.

 

[Illum]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

because 120v/220v is much harder to convert to 3.7..... than 5v...
if you find the actual charging circuit.. there isn't really that much..


110V AC OR 220V AC --> 3.7V DC
compared to 5V DC--> 3.7V DC

the thing is, the DSD charger is being fed by a 5.5VDC 450ma wallwort, I was referring to the big o'fat PCB board in the charging cradle...
I can understand it if there's an AC-DC conversion to work with but dood...its being fed with DC

well okay, its not as fat as it sounds but it does have alot more components than a single IC...
[not my pic]

 

[wapkil]

Re: Feeler: USB Micro Charger for Li-Ion/Poly Cells

An interesting thing about this charger is that one can charge a Li-Ion from 4 NiMHs (or alkalines, lithiums, etc. - anything between ~0.9V and 1.75V) with it. There are boxes that take 4 AAs, connect them in series and pretend to be an USB power source. I think they should work well with this charger.