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l_luv2_fly(at)yahoo.com
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 Posted: Sat Oct 15, 2011 6:57 am Post subject: Battery Charge Information |
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Hi All,
I need to build a battery charger to charge 3 AGM batteries wired in series. These are 12 + 12 + 4 volts. From the manufacturers data sheets I given to understand that the charge cycle is 2.4 to 2.5v per cell and the float cycle is 2.26 to 2.3v per cell.
I would like to build a battery charger with some "smarts" in it that will switch over to a float charge mode at the appropriate time and I would like to understand when to switch from charge to float. From my reading of http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery it looks like the change from charge to float occurs at 9 hours.
I know that there are many commercial chargers that do this and I was wondering is the change from charge to float time based or is it done by measuring voltage / current parameters ?
Thanks, Paul
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Sat Oct 15, 2011 8:46 am Post subject: Battery Charge Information |
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At 09:53 AM 10/15/2011, you wrote:
| Quote: | Hi All,
I need to build a battery charger to charge 3 AGM batteries wired in
series. These are 12 + 12 + 4 volts. From the manufacturers data
sheets I given to understand that the charge cycle is 2.4 to 2.5v
per cell and the float cycle is 2.26 to 2.3v per cell.
I would like to build a battery charger with some "smarts" in it
that will switch over to a float charge mode at the appropriate time
and I would like to understand when to switch from charge to
float. From my reading of
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
it looks like the change from charge to float occurs at 9 hours.
|
Sorta . . . what's your technology of choice? Analog
jelly beans or digital?
| Quote: | I know that there are many commercial chargers that do this and I
was wondering is the change from charge to float time based or is it
done by measuring voltage / current parameters ?
|
They vary. If you've got a lot of time, the easiest
is to apply constant current equal to 1/10 of the
array's a.h. capacity and watch the voltage. When
the voltage reaches 2.5 v/cell, start a timer for
some 'top off' cycle . . . say two hours. Then
drop to a maintenance voltage that is just a tad higher
than the open circuit. For 12v batteries, this is
about 13.0 volts so shoot for 2.2 volts per cell.
Real easy to do with a micro-controller if you
know how to herd the bytes. A little harder with
jelly-beans but doable. Here's the Schumacher
1562 profile.
http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg
It might be that you could 'jeep' a Schumacher
1562 electronics to do your task by fiddling with
some scaling resistors and increasing the charge
source voltage.
Bob . . .
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l_luv2_fly(at)yahoo.com
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| Posted: Sat Oct 15, 2011 9:42 am Post subject: Battery Charge Information |
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Bob,
Thanks for your thoughts. I had planned to build it with a PIC Micro.
Paul
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
To: aeroelectric-list(at)matronics.com
Sent: Saturday, October 15, 2011 11:42 AM
Subject: Re: Battery Charge Information
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 09:53 AM 10/15/2011, you wrote:
| Quote: | Hi All,
I need to build a battery charger to charge 3 AGM batteries wired in series. These are 12 + 12 + 4 volts. From the manufacturers data sheets I given to understand that the charge cycle is 2.4 to 2.5v per cell and the float cycle is 2.26 to 2.3v per cell.
I would like to build a battery charger with some "smarts" in it that will switch over to a float charge mode at the appropriate time and I would like to understand when to switch from charge to float. From my reading of http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery it looks like the change from charge to float occurs at 9 hours.
|
Sorta . . . what's your technology of choice? Analog
jelly beans or digital?
| Quote: | I know that there are many commercial chargers that do this and I was wondering is the change from charge to float time based or is it done by measuring voltage / current parameters ?
|
They vary. If you've got a lot of time, the easiest
is to apply constant current equal to 1/10 of the
array's a.h. capacity and watch the voltage. When
the voltage reaches 2.5 v/cell, start a timer for
some 'top off' cycle . . . say two hours. Then
drop to a maintenance voltage that is just a tad higher
than the open circuit. For 12v batteries, this is
about 13.0 volts so shoot for 2.2 volts per cell.
Real easy to do with a micro-controller if you
know how to herd the bytes. A little harder with
jelly-beans but doable. Here's the Schumacher
1562 profile.
http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg
It might be that you could 'jeep' a Schumacher
1562 electronics to do your task by fiddling with
some scaling resistors and increasing the charge
source voltage.
&reat content also available via -Mat===============
[quote][b]
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nuckolls.bob(at)aeroelect
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| Posted: Sat Oct 15, 2011 1:55 pm Post subject: Battery Charge Information |
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At 12:38 PM 10/15/2011, you wrote:
| Quote: | Bob,
Thanks for your thoughts. I had planned to build it with a PIC Micro.
|
aha! great! if you'd post your hardware proposal
sketches perhaps we could collaborate together
and perhaps inspire others to rise to the occasion
of their own ideas. I think the PICs are here
to stay . . .
Bob . . .
////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================
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l_luv2_fly(at)yahoo.com
Guest
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| Posted: Mon Oct 17, 2011 9:19 pm Post subject: Battery Charge Information |
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Bob,
Yes I just love PIC's. I am feeling a bit dated when I can tell you that first learned to tinker with this stuff on Data General Nova's and Motorola 6800's. The first real useful device I had was the 8051 and I can recall that it nearly used to bring tears to my eyes to try and get a serial i/o working in assembly language.
Fast forwarding 20 years to PIC's where a single line of code takes care of a serial i/o that is native to the chip, along with as many timers, ADC and parallel i/o all on a single chip. Gee its just too easy.
Cheers, Paul
do not archive.
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
At 12:38 PM 10/15/2011, you wrote:
| Quote: | Bob,
Thanks for your thoughts. I had planned to build it with a PIC Micro.
|
aha! great! if you'd post your hardware proposal
sketches perhaps we could collaborate together
and perhaps inspire others to rise to the occasion
of their own ideas. I think the PICs are here
to stay . . .
Bob . . .
[quote][b]
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james(at)etravel.org
Guest
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| Posted: Tue Oct 18, 2011 12:41 am Post subject: Battery Charge Information |
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Yep, they're terrific if you can code. Â I've done a PIC-based 2-1/4" gauge for my project, which shows three fuel tank levels on a small colour LCD display. Â Built-in A-D on the chip makes it much easier for someone like me who knows little of the mysteries of hardware.Â
James
On 18 October 2011 06:15, Paul McAllister <l_luv2_fly(at)yahoo.com (l_luv2_fly(at)yahoo.com)> wrote:
[quote] Bob,
Yes I just love PIC's. I am feeling a bit dated when I can tell you that first learned to tinker with this stuff on Data General Nova's and Motorola 6800's. The first real useful device I had was the 8051 and I can recall that it nearly used to bring tears to my eyes to try and get a serial i/o working in assembly language.
Fast forwarding 20 years to PIC's where a single line of code takes care of a serial i/o that is native to the chip, along with as many timers, ADC and parallel i/o all on a single chip. Gee its just too easy.
Cheers, Paul
do not archive.
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 12:38 PM 10/15/2011, you wrote:
| Quote: | Bob,
Thanks for your thoughts. I had planned to build it with a PIC Micro.
|
 aha! great! if you'd post your hardware proposal
 sketches perhaps we could collaborate together
 and perhaps inspire others to rise to the occasion
 of their own ideas. I think the PICs are here
 to stay . . .
   Bob . . .
Â
| Quote: |
ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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[b]
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