Formula for charging time of 12v battery

  • Thread starter Northern Night Sky
  • Start date
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Northern Night Sky

Guest
I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?
 
"Northern Night Sky"
I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?
Click to expand...

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?


..... Phil
 
On Wed, 9 Feb 2011 12:56:57 -0800 (PST), Northern Night Sky
<headbangerstudio@gmail.com> wrote:

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?
Click to expand...
The specs give a max expected charging time of 24 hours with nominal
wall voltage and the supplied AC adapter. Since it looks like the
adapter puts out DC and also that the charging circuit is a "smart"
charger, then the time using the solar panel would be similar.

--
Rich Webb Norfolk, VA
 
"Northern Night Sky"
"Phil Allison"
I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?
Click to expand...

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...

** No you cannot.

Fuck off, imbecile.


..... Phil
 
on 10/02/2011, George Herold supposed :
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:





"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.
Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??
Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.
Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery. 12 amp x hours. So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.) What was
the current rating on your AC adapter that took 17 hours?

george h.
Click to expand...
The charger according to the sales blurb supplies 500ma.
The 20 amp 120 volt house outlet is useless and probably wrong
information. Is not the normal US outlet limited to 15 amps?

--
John G
 
"Northern Night Sky"


** Drop dead - you PSYCHO fuckwit !!!
 
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil
Click to expand...
You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh! If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.
 
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com>
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:





"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -
Click to expand...
The 12Ah is the capacity of the battery. 12 amp x hours. So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.) What was
the current rating on your AC adapter that took 17 hours?

george h.
 
On Feb 9, 6:10 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Northern Night Sky"
 "Phil Allison"



I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...

** No you cannot.

    Fuck off,  imbecile.

....  Phil
Click to expand...
wow, what a typical answer from a Google Group! Your first answer was
passive-aggressive, at best. Then, your second is even worst.
Instead of telling me WHY it cannot work and educate me, you thought
it was a more logical and rational ideal to tell me to "fuck off". I
don't think you know nearly as much about the subject, as you claim.

If the Maximum charging power is 1amp at 15v, on a 12Ah battery, I'm
sure you can calculate the charging time.

Maybe I should go to some place more professional!
 
On Feb 9, 6:15 pm, George Herold <gher...@teachspin.com> wrote:
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:



On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

george h.
Click to expand...
THANK YOU George! The specs of my adapter are:

Input: AC120V 60Hz 16W
Output: 13.5VDC 500mA
 
On Feb 9, 6:24 pm, John G <greent...@ozemail.com.au> wrote:
on 10/02/2011, George Herold supposed :



On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.
Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??
Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.
Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

george h.

The charger according to the sales blurb supplies 500ma.
The 20 amp 120 volt house outlet is useless and probably wrong
information. Is not the normal US outlet limited to 15 amps?

--
John G
Click to expand...
I neglected to consider the adapter rating. You're right, it's a 15
amp outlet, in a 20 amp circuit.
 
Northern Night Sky wrote:
wow, what a typical answer from a Google Group!
Click to expand...

This a Usenet newsgroup, not a 'Google Group'. Just because you
access it through Google doesn't make it theirs.

Phil is mentaly ill, but once in a while he's right to tell people
off.


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.
 
On 02/09/2011 02:15 PM, George Herold wrote:
On Feb 9, 4:57 pm, Northern Night Sky<headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison"<phi...@tpg.com.au> wrote:





"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

.... Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh! If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery. 12 amp x hours. So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.) What was
the current rating on your AC adapter that took 17 hours?
Click to expand...
Not necessarily. You can't just stuff a constant current into a
lead-acid battery and expect it to be happy -- the usual method is to
charge it at a constant current (depending on the charger's
capabilities) until the voltage rises to about 2.4V/cell (with the exact
amount depending on the battery and the ambient temperature) then
holding the voltage constant and allowing the battery to accept as much
charge as it can at that voltage.

Actual charge time then varies with both the charger's ability to
deliver high current at first, and the battery's ability to absorb it later.

--

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

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On Feb 9, 5:23 pm, Northern Night Sky <headbangerstu...@gmail.com>
wrote:
On Feb 9, 6:15 pm, George Herold <gher...@teachspin.com> wrote:





On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:

On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

george h.

THANK YOU George!  The specs of my adapter are:

Input: AC120V 60Hz 16W
Output: 13.5VDC 500mA- Hide quoted text -

- Show quoted text -
Click to expand...
No problem, At 1/2 an amp times 17 hours you put a bit more than
8Ahrs into your battery. It wasn't discharged all the way. Which is
fine if it's a lead acid .

Phil A, knows a lot more than I do about electronics, but he's a
bit.....

George H.
 
On Feb 9, 8:25 pm, Tim Wescott <t...@seemywebsite.com> wrote:
On 02/09/2011 02:15 PM, George Herold wrote:





On Feb 9, 4:57 pm, Northern Night Sky<headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison"<phi...@tpg.com.au>  wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

Not necessarily.  You can't just stuff a constant current into a
lead-acid battery and expect it to be happy -- the usual method is to
charge it at a constant current (depending on the charger's
capabilities) until the voltage rises to about 2.4V/cell (with the exact
amount depending on the battery and the ambient temperature) then
holding the voltage constant and allowing the battery to accept as much
charge as it can at that voltage.

Actual charge time then varies with both the charger's ability to
deliver high current at first, and the battery's ability to absorb it later.

--

Tim Wescott
Wescott Design Serviceshttp://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details athttp://www.wescottdesign.com/actfes/actfes.html- Hide quoted text -

- Show quoted text -
Click to expand...
Thanks Tim, I didn't know that. I figured his charger would take care
of the messy details.

George H.
 
On Wed, 9 Feb 2011 14:15:42 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:





"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery. 12 amp x hours. So if your
solar charger provides 1 amp, then it will take about 12 hours.
Click to expand...
---
Sorry, but since there's no free lunch, that's just not true.

Rule of thumb, as I recall, is that the charging efficiency of a
lead-acid cell/battery is about 60%, so to get 12Ah into the battery
using a 1A constant-current source which will take it to its terminal
voltage will take about 20 hours.
---

(Assuming the battery is fully discharged at the start.) What was
the current rating on your AC adapter that took 17 hours?
Click to expand...
---
That may not be as relevant as it sounds because lead-acid chargers
are usually constant voltage affairs, and as the battery voltage rises
the current into the battery will fall.

---
JF
 
On Wed, 9 Feb 2011 20:16:16 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Feb 9, 5:23 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 6:15 pm, George Herold <gher...@teachspin.com> wrote:





On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:

On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.
(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

george h.

THANK YOU George!  The specs of my adapter are:

Input: AC120V 60Hz 16W
Output: 13.5VDC 500mA- Hide quoted text -

- Show quoted text -

No problem, At 1/2 an amp times 17 hours you put a bit more than
8Ahrs into your battery. It wasn't discharged all the way. Which is
fine if it's a lead acid .
Click to expand...
---
Half an amp times 17 hours is 8-1/2 amp hours out of the charger, but
due to efficiency considerations, that's not what you can get out of
the battery at that point.

Assuming a charging efficiency of 60%, in order to get 12Ah out of the
battery you'd have to put in 20, and at a constant half an amp that
would be 40 hours.
---

Phil A, knows a lot more than I do about electronics, but he's a
bit.....
Click to expand...
---
knowledgable?
---

George H.
Click to expand...
---
JF
 
On Feb 10, 7:33 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 9 Feb 2011 14:15:42 -0800 (PST), George Herold





gher...@teachspin.com> wrote:
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.

---
Sorry, but since there's no free lunch, that's just not true.

Rule of thumb, as I recall, is that the charging efficiency of a
lead-acid cell/battery is about 60%, so to get 12Ah into the battery
using a 1A constant-current source which will take it to its terminal
voltage will take about 20 hours.
Click to expand...
As bad as 60%? I didn't know that. The only time I've used/measured
battery capacity was in rapid charging of NiCad's. And there the
efficiency was pretty good.

George H.
---

(Assuming the battery is fully discharged at the start.)   What was
the current rating on your AC adapter that took 17 hours?

---
That may not be as relevant as it sounds because lead-acid chargers
are usually constant voltage affairs, and as the battery voltage rises
the current into the battery will fall.

---
JF- Hide quoted text -

- Show quoted text -
Click to expand...
 
On Thu, 10 Feb 2011 07:23:37 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Feb 10, 7:33 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 9 Feb 2011 14:15:42 -0800 (PST), George Herold





gher...@teachspin.com> wrote:
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery.  How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

....  Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh!  If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery.  12 amp x hours.  So if your
solar charger provides 1 amp, then it will take about 12 hours.

---
Sorry, but since there's no free lunch, that's just not true.

Rule of thumb, as I recall, is that the charging efficiency of a
lead-acid cell/battery is about 60%, so to get 12Ah into the battery
using a 1A constant-current source which will take it to its terminal
voltage will take about 20 hours.

As bad as 60%? I didn't know that. The only time I've used/measured
battery capacity was in rapid charging of NiCad's. And there the
efficiency was pretty good.

George H.
Click to expand...
---
http://photovoltaics.sandia.gov/docs/PDF/batpapsteve.pdf

---
JF
 
On Feb 10, 11:25 am, John Fields <jfie...@austininstruments.com>
wrote:
On Thu, 10 Feb 2011 07:23:37 -0800 (PST), George Herold





gher...@teachspin.com> wrote:
On Feb 10, 7:33 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 9 Feb 2011 14:15:42 -0800 (PST), George Herold

gher...@teachspin.com> wrote:
On Feb 9, 4:57 pm, Northern Night Sky <headbangerstu...@gmail.com
wrote:
On Feb 9, 5:37 pm, "Phil Allison" <phi...@tpg.com.au> wrote:

"Northern Night Sky"

I have a Powerpack 300, which is a 12v battery at 12Ah.

Using the AC adapter with the house outlet (20amp at 120v) it takes 17
hours to fully charge the battery. How would I calculate the
(approximate) time it would take to charge the battery, using a solar
panel that draws 1amp at 15v?

** Don't solar panels only work when the sun shineth brightly ??

Any such predictions would have to involve detailed knowledge of the local
weather, cloud cover and solar illumination levels.

Wouldn't it ?

.... Phil

You still can get an approximate time of how long it would take to
charge the battery, giving the variables I've provided...Duh! If I
get 5 hours of sunshine/day, then I'll do the math in consequence.
I'm still interested on getting the FORMULA, as per my original
question.- Hide quoted text -

- Show quoted text -

The 12Ah is the capacity of the battery. 12 amp x hours. So if your
solar charger provides 1 amp, then it will take about 12 hours.

---
Sorry, but since there's no free lunch, that's just not true.

Rule of thumb, as I recall, is that the charging efficiency of a
lead-acid cell/battery is about 60%, so to get 12Ah into the battery
using a 1A constant-current source which will take it to its terminal
voltage will take about 20 hours.

As bad as 60%?  I didn't know that.  The only time I've used/measured
battery capacity was in rapid charging of NiCad's.  And there the
efficiency was pretty good.

George H.

---http://photovoltaics.sandia.gov/docs/PDF/batpapsteve.pdf

---
JF- Hide quoted text -

- Show quoted text -
Click to expand...
That's interesting, Thanks JF.
Since the lead acid's loose efficiency above an 80% state of charge
(SOC). Could you just operate them up to 80% SOC in a photo voltaic
system where you might want maximum efficiency? Or are the batteries
'damaged' by not being completly charged?

George H.
 
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