charge/regulate for Li-Poly Cell

S

starfire

Guest
Has anyone run across a case of having to charge a single Li-Poly cell
(3.7VDC nominal cell voltage with input voltages ranging from 4 to 7VDC) and
also regulate the output for a 3.3VDC circuit?

Thanks.

Dave
 
"starfire" <starfire151@cableone.net> wrote in message
news:10ategr3chf7h29@corp.supernews.com...
Has anyone run across a case of having to charge a single Li-Poly cell
(3.7VDC nominal cell voltage with input voltages ranging from 4 to 7VDC)
and
also regulate the output for a 3.3VDC circuit?

Thanks.

Dave
Click to expand...
yes. I used a max1551/max1555 to do the charging, and a low-power LDO
regulator to provide +3V3. I built an input circuit for the maxim chip that
allows 50Vac up its ass without killing it (dc plug-pack used for charging,
what happens if customer uses the wrong one). Dont forget that li-poly
batteries should not be charged belo 0C and above (IIRC) 45C. Current
limiting the load is pretty much mandatory - these things EXPLODE and/or
catch fire when abused.

Terry
 
Thanks for the info, Terry. I will check into those parts.

I've also looked at using an Analog Devices ADP3820AR-4.1 Li-Ion Battery
Charger for the cell then a follow-on stage of an Analog Devices
ADP3303AR-3.3 for the LDO regulator. I've ordered samples for these parts.

Thanks, also, for the "heads-up" on Li-Poly cells. We're using the Kokam
batteries (high capacity 3270mAh) in a portable application. We will make
sure of the operating temperature range and the output will be limited by
the regulator.

Thanks again.

Dave

"Terry Given" <the_domes@xtra.co.nz> wrote in message
news:Njzrc.8282$XI4.305244@news.xtra.co.nz...
"starfire" <starfire151@cableone.net> wrote in message
news:10ategr3chf7h29@corp.supernews.com...
Has anyone run across a case of having to charge a single Li-Poly cell
(3.7VDC nominal cell voltage with input voltages ranging from 4 to 7VDC)
and
also regulate the output for a 3.3VDC circuit?

Thanks.

Dave



yes. I used a max1551/max1555 to do the charging, and a low-power LDO
regulator to provide +3V3. I built an input circuit for the maxim chip
that
allows 50Vac up its ass without killing it (dc plug-pack used for
charging,
what happens if customer uses the wrong one). Dont forget that li-poly
batteries should not be charged belo 0C and above (IIRC) 45C. Current
limiting the load is pretty much mandatory - these things EXPLODE and/or
catch fire when abused.

Terry
Click to expand...
 
"starfire" <starfire151@cableone.net> wrote in message
news:10av2bvliipvlc2@corp.supernews.com...
Thanks for the info, Terry. I will check into those parts.

I've also looked at using an Analog Devices ADP3820AR-4.1 Li-Ion Battery
Charger for the cell then a follow-on stage of an Analog Devices
ADP3303AR-3.3 for the LDO regulator. I've ordered samples for these
parts.

Thanks, also, for the "heads-up" on Li-Poly cells. We're using the Kokam
batteries (high capacity 3270mAh) in a portable application. We will make
sure of the operating temperature range and the output will be limited by
the regulator.

Thanks again.

Dave
Click to expand...
Hi Dave,
you are welcome. I have to be careful about that, because my battery sits on
a persons head, by their left temple - I can see how they would get all
pissy if it blew up/caught fire (arent customers picky)

Cheers
Terry
 
Hi Dave,
you are welcome. I have to be careful about that, because my battery sits
on
a persons head, by their left temple - I can see how they would get all
pissy if it blew up/caught fire (arent customers picky)
Click to expand...
Bluetooth headset?

Did anyone notice that Uhura's earpiece is already here?
 
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:qZGdnam8go20lC3dRVn-uQ@comcast.com...
Hi Dave,
you are welcome. I have to be careful about that, because my battery
sits
on
a persons head, by their left temple - I can see how they would get all
pissy if it blew up/caught fire (arent customers picky)

Bluetooth headset?

Did anyone notice that Uhura's earpiece is already here?
Click to expand...
Nah, something entirely different. Much higher carrier frequency, much lower
bandwidth, but I'm being paid to do it so alas no details.

Terry
 
"Terry Given" <the_domes@xtra.co.nz> wrote in message
news:fKXrc.8827$XI4.319103@news.xtra.co.nz...
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:qZGdnam8go20lC3dRVn-uQ@comcast.com...

Hi Dave,
you are welcome. I have to be careful about that, because my battery
sits on a persons head, by their left temple - I can see how they would
get all
pissy if it blew up/caught fire (arent customers picky)

Bluetooth headset?


Nah, something entirely different. Much higher carrier frequency, much
lower
bandwidth, but I'm being paid to do it so alas no details.

Terry

Hi Terry,
Click to expand...
Sound like you're powering an ear implant at maybe 40MHz carrier. Been
there, done that.
Regards
Harry
 
So your "heads up" is REALLY "heads up" :)

.... snip...
Hi Dave,
you are welcome. I have to be careful about that, because my battery sits
on
a persons head, by their left temple - I can see how they would get all
pissy if it blew up/caught fire (arent customers picky)

Cheers
Terry
Click to expand...
 
Nah, something entirely different. Much higher carrier frequency, much
lower
bandwidth, but I'm being paid to do it so alas no details.
Click to expand...
I'd be interested in whatever you can discuss about how you treat the
battery in this application.
 
"starfire" <starfire151@cableone.net> wrote in message
news:10b1juebfds624b@corp.supernews.com...
So your "heads up" is REALLY "heads up" :)

... snip...

Hi Dave,
you are welcome. I have to be careful about that, because my battery
sits
on
a persons head, by their left temple - I can see how they would get all
pissy if it blew up/caught fire (arent customers picky)

Cheers
Terry
Click to expand...
:) :) :) :) well said.

Terry
 
"Harry Dellamano" <harryd@tdsystems.org> wrote in message
news:6%2sc.5694$o97.2861@nwrddc01.gnilink.net...
"Terry Given" <the_domes@xtra.co.nz> wrote in message
news:fKXrc.8827$XI4.319103@news.xtra.co.nz...
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:qZGdnam8go20lC3dRVn-uQ@comcast.com...

Hi Dave,
you are welcome. I have to be careful about that, because my battery
sits on a persons head, by their left temple - I can see how they would
get all
pissy if it blew up/caught fire (arent customers picky)

Bluetooth headset?


Nah, something entirely different. Much higher carrier frequency, much
lower
bandwidth, but I'm being paid to do it so alas no details.

Terry

Hi Terry,
Sound like you're powering an ear implant at maybe 40MHz carrier. Been
there, done that.
Regards
Harry
Click to expand...
Nope. wrong app, much, much, much higher frequencies :) nice guess though.

Terry
 
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:RoSdnXUFyoS-TC3dRVn-hg@comcast.com...
Nah, something entirely different. Much higher carrier frequency, much
lower
bandwidth, but I'm being paid to do it so alas no details.

I'd be interested in whatever you can discuss about how you treat the
battery in this application.
Click to expand...
most of it has been said. Max1555/1551 does almost all of the work. A DC
adaptor is used for charging, so I built a circuit that prevents more than
6V up the max chip (say someone plugs a 15V adaptor into the socket). A
window comparator & NTC shut off charging (and the bulk of load current
consumption) if 0 < T < 45C. I have not finished the load short-circuit
prevention - fall-back is series 20R, but it eats 10% of my battery, so I am
looking at polyfuses, PTCs etc.

Terry
 
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