Bret Cahill
Guest
Thu Dec 15, 2011 11:01 pm
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts
when fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
Bret Cahill
Stumpy
Guest
Thu Dec 15, 2011 11:03 pm
"Bret Cahill" <BretCahill_at_peoplepc.com> wrote in message
news:d5550766-f09b-4bf9-9fff-cb7f93221612_at_x7g2000yqb.googlegroups.com...
Quote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts
when fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
Bret Cahill
Sounds like a low risk trial and error, the consequences of failure are
small.
Ian Field
Guest
Thu Dec 15, 2011 11:24 pm
"Stumpy" <perilmung_at_spamnet.corn> wrote in message
news:yu-dnSv3FdIq83fTnZ2dnUVZ_rWdnZ2d_at_earthlink.com...
Quote:
"Bret Cahill" <BretCahill_at_peoplepc.com> wrote in message
news:d5550766-f09b-4bf9-9fff-cb7f93221612_at_x7g2000yqb.googlegroups.com...
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts
when fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
Bret Cahill
Sounds like a low risk trial and error, the consequences of failure are
small.
Sounds like the greater risk is the possibility of over-discharging the Li
cell.
Best not to overload a fully charged cell either - lithium fires aren't
funny.
Tom Biasi
Guest
Fri Dec 16, 2011 12:55 am
On Thu, 15 Dec 2011 13:01:38 -0800 (PST), Bret Cahill
<BretCahill_at_peoplepc.com> wrote:
Quote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts
when fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
Bret Cahill
The camera is spec' ed for 3 volts.
You can get the correct battery for about 8 buck American. A CRV3
Robert Roland
Guest
Fri Dec 16, 2011 2:08 am
On Thu, 15 Dec 2011 13:01:38 -0800 (PST), Bret Cahill
<BretCahill_at_peoplepc.com> wrote:
Quote:
Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage.
Although the nominal voltage is 3.6V, the voltage will be considerably
higher than that when the battery is fully charged. I'm nut sure about
Li-Ion, but LiPo batteries are 4.2V when fully charged, and 3.7V
nominal, so it should be close to that.
--
RoRo
Bret Cahill
Guest
Fri Dec 16, 2011 2:11 am
Quote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts
when fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
Bret Cahill
Sounds like a low risk trial and error, the consequences of failure are
small.
Sounds like the greater risk is the possibility of over-discharging the Li
cell.
I was going to have several in parallel with a plug.
Quote:
Best not to overload a fully charged cell either - lithium fires aren't
funny.
Tim Wescott
Guest
Fri Dec 16, 2011 6:47 pm
On Thu, 15 Dec 2011 13:01:38 -0800, Bret Cahill wrote:
Quote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts when
fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
As noted, when freshly charged the Li-Ion cells will be more like 4.2V,
and if you discharge them too far (I can't remember the exact number but
I think it's above 3V) you'll permanently damage them.
Make an adapter board with an LDO that drops from 3.6V down to 3V, and
that cuts off when the cell voltage drops below the critical value.
Better yet (if you like fiddling), make the thing with a switching supply
to get your 20% longer use between recharge.
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Ian Field
Guest
Fri Dec 16, 2011 7:10 pm
"Tim Wescott" <tim_at_seemywebsite.com> wrote in message
news:TuadnW8oVvveGXbTnZ2dnUVZ_tudnZ2d_at_web-ster.com...
Quote:
On Thu, 15 Dec 2011 13:01:38 -0800, Bret Cahill wrote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts when
fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
As noted, when freshly charged the Li-Ion cells will be more like 4.2V,
and if you discharge them too far (I can't remember the exact number but
I think it's above 3V) you'll permanently damage them.
Make an adapter board with an LDO that drops from 3.6V down to 3V, and
that cuts off when the cell voltage drops below the critical value.
Better yet (if you like fiddling), make the thing with a switching supply
to get your 20% longer use between recharge.
If the target voltage is 3.3V from a single lithium cell there may be off
the shelf chips that have UVLO built in.
krw@att.bizzzzzzzzzzzz
Guest
Sat Dec 17, 2011 2:02 am
On Fri, 16 Dec 2011 11:47:47 -0600, Tim Wescott <tim_at_seemywebsite.com> wrote:
Quote:
On Thu, 15 Dec 2011 13:01:38 -0800, Bret Cahill wrote:
This camera draws so much current it makes a good hand warmer. On the
down side a pair of alkaline AA batteries barely reaches 3.3 volts when
fresh and the camera shuts down below 3 V.
I have several old cell phone Li-Ion 3.6 V batteries, just 10% higher
than the rated voltage. Would 3.6 fry the electronics?
As noted, when freshly charged the Li-Ion cells will be more like 4.2V,
and if you discharge them too far (I can't remember the exact number but
I think it's above 3V) you'll permanently damage them.
The charge voltage depends on the cell and, of course, the charger. Chargers
come with either a 4.1V or 4.2V terminal charge voltage. There isn't much to
be had under about 3.3V. We generally set the LV drop-out at about 3.4V.
There really isn't much under about 3.5V (maybe 10%, IIRC).
Quote:
Make an adapter board with an LDO that drops from 3.6V down to 3V, and
that cuts off when the cell voltage drops below the critical value.
Better yet (if you like fiddling), make the thing with a switching supply
to get your 20% longer use between recharge.
BTDT.
