Battery charging question...

D

Dave

Guest
Aren't lead-acid batteries charged (or recharged) by sending something like
15 or 16 volts at one amp or less *backwards* through them? (IE the
normally negative lead which is attached to the negative terminal of the
battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave
 
On Oct 15, 10:12 am, "Dave" <db5...@hotmail.com> wrote:
Aren't lead-acid batteries charged (or recharged) by sending something like
15 or 16 volts at one amp or less *backwards* through them? (IE the
normally negative lead which is attached to the negative terminal of the
battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave
Click to expand...

No.

It's charged by sending slightly more than 12V (about 14.4V
typically).

Positive from charger goes to positive on battery, and negative to
negative.

See http://www.batteryuniversity.com/partone-13.htm

If you're charging a car battery, also (slowly and carefully!
preferably with gloves and eye protection) add distilled water to top
up the battery. You don't want to charge a dry battery.

Michael
 
<mrdarrett@gmail.com> wrote in message
news:4b7da4b7-a56e-4b45-8eb6-f6ad9d60e9e5@g25g2000prf.googlegroups.com...
On Oct 15, 10:12 am, "Dave" <db5...@hotmail.com> wrote:
Aren't lead-acid batteries charged (or recharged) by sending something
like
15 or 16 volts at one amp or less *backwards* through them? (IE the
normally negative lead which is attached to the negative terminal of the
battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave


No.

It's charged by sending slightly more than 12V (about 14.4V
typically).

Positive from charger goes to positive on battery, and negative to
negative.

See http://www.batteryuniversity.com/partone-13.htm

If you're charging a car battery, also (slowly and carefully!
preferably with gloves and eye protection) add distilled water to top
up the battery. You don't want to charge a dry battery.

Michael
Click to expand...
*Thank you* Michael. Very much. I knew I had to be wrong. What you
describe explains perfectly what I am looking at, and makes a lot more sense
than my own concoction of realities. It is appreciated.

Dave
 
On Wed, 15 Oct 2008 10:20:44 -0700, mrdarrett wrote:

On Oct 15, 10:12 am, "Dave" <db5...@hotmail.com> wrote:
Aren't lead-acid batteries charged (or recharged) by sending something
like 15 or 16 volts at one amp or less *backwards* through them? (IE
the normally negative lead which is attached to the negative terminal
of the battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave


No.

It's charged by sending slightly more than 12V (about 14.4V typically).

Positive from charger goes to positive on battery, and negative to
negative.

See http://www.batteryuniversity.com/partone-13.htm
Click to expand...
When you do this (raise the voltage to the battery), you cause current to
flow _into_ the + terminal instead of _out_ -- this reverses the chemical
reaction that discharges the battery (usually by plating metal back onto
the electrodes).

So _something_ happens in reverse, it's just not the voltage!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On Oct 15, 9:26 pm, "Dave" <db5...@hotmail.com> wrote:
mrdarr...@gmail.com> wrote in message

news:4b7da4b7-a56e-4b45-8eb6-f6ad9d60e9e5@g25g2000prf.googlegroups.com...



On Oct 15, 10:12 am, "Dave" <db5...@hotmail.com> wrote:
Aren't lead-acid batteries charged (or recharged) by sending something
like
15 or 16 volts at one amp or less *backwards* through them? (IE the
normally negative lead which is attached to the negative terminal of the
battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave

No.

It's charged by sending slightly more than 12V (about 14.4V
typically).

Positive from charger goes to positive on battery, and negative to
negative.

Seehttp://www.batteryuniversity.com/partone-13.htm

If you're charging a car battery, also (slowly and carefully!
preferably with gloves and eye protection) add distilled water to top
up the battery. You don't want to charge a dry battery.

Michael

*Thank you* Michael. Very much. I knew I had to be wrong. What you
describe explains perfectly what I am looking at, and makes a lot more sense
than my own concoction of realities. It is appreciated.

Dave
Click to expand...

You're welcome.

My son has a 6V electric tricycle we got him for his 6th birthday.
Long story short, the charger that came with it was inadequate - it
cooks the battery. 8+ volts, when 7.50V should be the Absolute Max
for 6V sealed-lead-acid. Made in China...

I charged the battery for awhile using a spare cell phone charger wall
wart transformer, then got tired of monitoring the voltage every 30
minutes to avoid overcharging... my limited electronics knowledge
didn't allow me to build a very good automatic voltage regulator.

I then bought a switchable 6/12V battery charger from Wal-Mart, ~$15.
The 12V setting works great for maintaining the car batteries too.

Regards,

Michael
 
"Tim Wescott" <tim@justseemywebsite.com> wrote in message
news:eek:qGdnZXlso8qWGvVnZ2dnUVZ_vCdnZ2d@web-ster.com...
On Wed, 15 Oct 2008 10:20:44 -0700, mrdarrett wrote:

On Oct 15, 10:12 am, "Dave" <db5...@hotmail.com> wrote:
Aren't lead-acid batteries charged (or recharged) by sending something
like 15 or 16 volts at one amp or less *backwards* through them? (IE
the normally negative lead which is attached to the negative terminal
of the battery is made positive, and it's counterpart negative, in some
more-or-less small excess of the normal voltage at which the battery
operates.)

If not, someone please enlighten me before I blow something up.

Many thanks,

Dave


No.

It's charged by sending slightly more than 12V (about 14.4V typically).

Positive from charger goes to positive on battery, and negative to
negative.

See http://www.batteryuniversity.com/partone-13.htm


When you do this (raise the voltage to the battery), you cause current to
flow _into_ the + terminal instead of _out_ -- this reverses the chemical
reaction that discharges the battery (usually by plating metal back onto
the electrodes).

So _something_ happens in reverse, it's just not the voltage!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Click to expand...

Yeah. I realize that now. For some reason I had a mental block for a
couple days, and couldn't get past it. I now realize that what I had in
mind would kill said battery. Not good. sigh I've been out of the loop
for fifteen years, and sometimes experience a brain-fart that I know isn't
right, but can't figure out why.

I am trying to help a guy I know who is totally wheel-chair bound, and
parallyzed from the chest down. His automatic door opener wasn't working
due to dead battery, and when I tested the charge voltage I saw what you
describe, but couldn't get past my brain-fart. Decided that since the
original battery had been in there for over six years, the charging circuit
was probably not to blame and should be left alone. I knew enough to not
trust my faulty analytical skills at least. Today I am replacing a shorted
capacitor on the circuitboard of his front-door intercom. Trying to decide
what to do with the transistor associated with that capacitor. Will test it
thoroughly, and maybe replace it if it does anything funny or questionable.
Have already used the diode test on my multimeter to verify it's polarity
and basic functions. Today, when I have more time, will use my Sencore
supercricket to check it out more completely.

Right now I am wondering whether using a 50V capacitor in the place of a 35V
of the same value (220uF) would have any untoward consequences. That is
what I have on hand, and if it will fit in the space provided might use.
Think I'll try to stick with the exact replacement if I can find a high-temp
version of the correct voltage. It'll just push the repair back a couple
days.

Thanks,

Dave
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top