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Harbor Freight battery float charger #42292 circuit?
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P E Schoen
Nov 21, 2016, 2:24:48 PM11/21/16
to
I have one of the cheap ($5) Harbor Freight lead-acid battery float chargers
and I found that it was not working (it may have been damaged some time
ago - I had the case open). I traced the circuit and it is basically a FWB
and capacitor providing 25 VDC to a 7805 regulator with resistors to set the
output to about 13.5 volts. But it also has a TIP41 NPN BJT with a diode and
LED to the base, with the collector of a S9013 NPN and some resistors that
appear to be intended to stop charging or perhaps inhibit charging if the
battery voltage is too low. The schematics of various versions, and some
modifications, are in the following:
http://www.desert-home.com/2012/02/battery-charging-harbor-freight-item.html
http://www.desert-home.com/2012/03/battery-charging-part-2-harbor-freight.html
http://www.desert-home.com/2012/07/battery-charging-part-3-harbor-freight.html
The 7805 was blown in my unit so I replaced it with a 78M05 and I added a
trimpot to adjust output to 13.5V. I also added a diode in series with the
output to avoid damage from reversal. And I also removed R4 which
essentially eliminates the function of the TIP41. It looks like the S9013
transistor is biased so that it will turn on when the voltage from the
negative output lead to circuit ground exceeds 4.9V, and that will turn off
the base drive to the TIP41 and turn off the output and the indicator LED.
It seems to work OK now and it is holding a charge of 13.23V on a 12 A-h SLA
I charged overnight at about 0.33A. The battery read 13.13V when
disconnected and a minute later dropped to 13.00. When reconnected it
charged at 0.25A and after a minute dropped to 0.15A.
I had planned to build a high-tech charger/monitor using a PIC, and I still
may do so, but for now I just want something that works. I might tweak the
voltage down to about 13.2V which should be plenty to maintain charge on a
FLA 100 A-h deep cycle battery I have, as well as the starting battery of my
seldom used truck.
I also have a gel-cell SLA charger that I need to test.
Any ideas about that odd circuit with the TIP41?
Thanks,
Paul
and I found that it was not working (it may have been damaged some time
ago - I had the case open). I traced the circuit and it is basically a FWB
and capacitor providing 25 VDC to a 7805 regulator with resistors to set the
output to about 13.5 volts. But it also has a TIP41 NPN BJT with a diode and
LED to the base, with the collector of a S9013 NPN and some resistors that
appear to be intended to stop charging or perhaps inhibit charging if the
battery voltage is too low. The schematics of various versions, and some
modifications, are in the following:
http://www.desert-home.com/2012/02/battery-charging-harbor-freight-item.html
http://www.desert-home.com/2012/03/battery-charging-part-2-harbor-freight.html
http://www.desert-home.com/2012/07/battery-charging-part-3-harbor-freight.html
The 7805 was blown in my unit so I replaced it with a 78M05 and I added a
trimpot to adjust output to 13.5V. I also added a diode in series with the
output to avoid damage from reversal. And I also removed R4 which
essentially eliminates the function of the TIP41. It looks like the S9013
transistor is biased so that it will turn on when the voltage from the
negative output lead to circuit ground exceeds 4.9V, and that will turn off
the base drive to the TIP41 and turn off the output and the indicator LED.
It seems to work OK now and it is holding a charge of 13.23V on a 12 A-h SLA
I charged overnight at about 0.33A. The battery read 13.13V when
disconnected and a minute later dropped to 13.00. When reconnected it
charged at 0.25A and after a minute dropped to 0.15A.
I had planned to build a high-tech charger/monitor using a PIC, and I still
may do so, but for now I just want something that works. I might tweak the
voltage down to about 13.2V which should be plenty to maintain charge on a
FLA 100 A-h deep cycle battery I have, as well as the starting battery of my
seldom used truck.
I also have a gel-cell SLA charger that I need to test.
Any ideas about that odd circuit with the TIP41?
Thanks,
Paul
Carl Ijames
Nov 21, 2016, 3:58:36 PM11/21/16
to
"P E Schoen" wrote in message news:o0vhkp$le0$1...@dont-email.me...
===============================================================
I don't start my pickup for days at a time and the batteries were getting a
bit weak last winter so I bought a little solar cell charger. Don't know if
it helped or not, but the batteries made it through winter and then died in
the summer (got 5 years from 6 year warranty batteries so no complaints).
Found out warranties are much shorter now and prices have doubled, sigh.
Anyway, I was a bit concerned about overcharging and needed a toy so I
bought one of these to play with:
https://www.amazon.com/gp/product/B01HZ8HZQ6/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
It is a "MPPT Solar Panel Controller Battery Charging Board 1-100W 5A 9V 12V
18V 24V Solar Energy Renewable" populated board, no case or leads. I had
fantasies that it would be a buck boost circuit so would charge a 12 V
battery even when the solar panel output was less than 12 V, but no, it is
only a buck. What did I expect for $11, anyway :-). The solar panel is
https://www.amazon.com/gp/product/B012ZHGGXU/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1,
"ALLPOWERS 18V 7.5W Portable Solar Car Boat Power Sunpower Solar Panel
Battery Charger Maintainer for Automobile Motorcycle Tractor Boat
Batteries", just because that was the cheapest I found at the time. From my
research it seems that with 15W or less panels and a car sized battery a
controller isn't needed as you shouldn't be able to overcharge the battery
anyway. I wanted to play so I got the controller. The solar panel has a
cigarette lighter adapter to connect to the vehicle, with a little LED that
has always bugged me since it draws current when the sun is down. Only 5 mA
but I cut it out anyway. There is a Schottky diode in the panel to prevent
battery discharge when the sun is down, so that is nice even without an
external controller. There is an LED on the controller that only draws from
the solar panel, and I verified that it draws no current from the battery
when the sun is down. My dinky panel topped out at about 300 mA the day I
was making measurements so the 5A rating is way overkill but it was about
the smallest and cheapest I found. There is a pot for output voltage
adjust, it comes preset for 13.5 V according to my meter, so I left that
alone. There is a second pot for MPPT adjust, but absolutely no
documentation came with it so I have no idea what this does. I emailed the
vendor and asked for any info and they sent a hand drawn figure showing the
input and output pins, just like on the board itself, but no other info,
sigh. Anyway, it's double the cost of the Harbor Freight units but you
don't have to rebuild it and you couldn't build it for twice that to use as
a general power supply or a solar charger controller, but you do have to
provide your own enclosure. I tried to play a little checking the output
current and voltage and solar panel voltage while moving it around, and it
did seem to change the panel voltage with load but I won't swear it was
really MPPT. Just a long winded suggestion if you want to explore more
options than your Yuasa.
-----
Regards,
Carl Ijames
I don't start my pickup for days at a time and the batteries were getting a
bit weak last winter so I bought a little solar cell charger. Don't know if
it helped or not, but the batteries made it through winter and then died in
the summer (got 5 years from 6 year warranty batteries so no complaints).
Found out warranties are much shorter now and prices have doubled, sigh.
Anyway, I was a bit concerned about overcharging and needed a toy so I
bought one of these to play with:
https://www.amazon.com/gp/product/B01HZ8HZQ6/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
It is a "MPPT Solar Panel Controller Battery Charging Board 1-100W 5A 9V 12V
18V 24V Solar Energy Renewable" populated board, no case or leads. I had
fantasies that it would be a buck boost circuit so would charge a 12 V
battery even when the solar panel output was less than 12 V, but no, it is
only a buck. What did I expect for $11, anyway :-). The solar panel is
https://www.amazon.com/gp/product/B012ZHGGXU/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1,
"ALLPOWERS 18V 7.5W Portable Solar Car Boat Power Sunpower Solar Panel
Battery Charger Maintainer for Automobile Motorcycle Tractor Boat
Batteries", just because that was the cheapest I found at the time. From my
research it seems that with 15W or less panels and a car sized battery a
controller isn't needed as you shouldn't be able to overcharge the battery
anyway. I wanted to play so I got the controller. The solar panel has a
cigarette lighter adapter to connect to the vehicle, with a little LED that
has always bugged me since it draws current when the sun is down. Only 5 mA
but I cut it out anyway. There is a Schottky diode in the panel to prevent
battery discharge when the sun is down, so that is nice even without an
external controller. There is an LED on the controller that only draws from
the solar panel, and I verified that it draws no current from the battery
when the sun is down. My dinky panel topped out at about 300 mA the day I
was making measurements so the 5A rating is way overkill but it was about
the smallest and cheapest I found. There is a pot for output voltage
adjust, it comes preset for 13.5 V according to my meter, so I left that
alone. There is a second pot for MPPT adjust, but absolutely no
documentation came with it so I have no idea what this does. I emailed the
vendor and asked for any info and they sent a hand drawn figure showing the
input and output pins, just like on the board itself, but no other info,
sigh. Anyway, it's double the cost of the Harbor Freight units but you
don't have to rebuild it and you couldn't build it for twice that to use as
a general power supply or a solar charger controller, but you do have to
provide your own enclosure. I tried to play a little checking the output
current and voltage and solar panel voltage while moving it around, and it
did seem to change the panel voltage with load but I won't swear it was
really MPPT. Just a long winded suggestion if you want to explore more
options than your Yuasa.
-----
Regards,
Carl Ijames
bloggs.fred...@gmail.com
Nov 21, 2016, 6:06:55 PM11/21/16
to
mrda...@gmail.com
Nov 21, 2016, 7:14:44 PM11/21/16
to
You would think that in this era of energy efficiency, linear voltage regulators + 50/60Hz transformers would be frowned upon...
Thanks!
Michael
Jim Thompson
Nov 21, 2016, 7:35:35 PM11/21/16
to
On Mon, 21 Nov 2016 15:57:49 -0500, "Carl Ijames"
<carl.ija...@ZZxyz.verizon.net> wrote:
[snip]
That solar approach is appealing. I have a pick-em-up truck that gets
driven maybe once a month (bought new, 15 years old with only 39,000
miles ;-).
It would be troublesome to plug it in to mains between trips, but the
solar, particularly here in AZ, should work great.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I'm looking for work... see my website.
<carl.ija...@ZZxyz.verizon.net> wrote:
[snip]
driven maybe once a month (bought new, 15 years old with only 39,000
miles ;-).
It would be troublesome to plug it in to mains between trips, but the
solar, particularly here in AZ, should work great.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I'm looking for work... see my website.
Dave Platt
Nov 21, 2016, 8:01:00 PM11/21/16
to
In article <09ba71b9-6a5c-4562...@googlegroups.com>,
efficiency" members of the Deltran Battery Tender family. The biggest
of these seems to be the 5-ampere model.
<mrda...@gmail.com> wrote:
>On that note, are there any good, reasonably-cheap SMPS 12V (14.4v?) battery chargers?
>
>You would think that in this era of energy efficiency, linear voltage regulators +
>50/60Hz transformers would be frowned upon...
If you can get by with modest charge rates, there are "high
>On that note, are there any good, reasonably-cheap SMPS 12V (14.4v?) battery chargers?
>
>You would think that in this era of energy efficiency, linear voltage regulators +
>50/60Hz transformers would be frowned upon...
efficiency" members of the Deltran Battery Tender family. The biggest
of these seems to be the 5-ampere model.
P E Schoen
Nov 22, 2016, 3:22:49 AM11/22/16
to
Fred Bloggs wrote in message
news:a32be85b-3763-4715...@googlegroups.com...
> The TIP41 and S9013 form a comparator with positive feedback. No need for
> adding your series diode as the TIP41 and its base 1N4007 prevent any
> reverse currents from the battery. If the battery has a shorted cell or is
> otherwise damagingly low, the TIP41 should come out of saturation allowing
> the S9013 to turn on and start diverting TIP41 base current etc until
> TIP41 is completely off and S9013 is saturated on. But that's a real rough
> HFE dependent threshold.
I did a simulation and it seems to work OK according to the schematic shown
in the first of the links above in the OP, but R5 is actually 400 ohms and
not 400k. It also seems to be protected against reverse connection as you
describe. Here is the simulation with steps of battery voltage from 8 volts
to 16 volts 1/2 volt per step, then zero volts (short) and -12V (reversed
battery).
http://enginuitysystems.com/pix/electronics/HF_Float_Charger.png
And the ASC file:
http://enginuitysystems.com/pix/electronics/HF_Float_Charger.asc
Thanks,
Paul
news:a32be85b-3763-4715...@googlegroups.com...
> The TIP41 and S9013 form a comparator with positive feedback. No need for
> adding your series diode as the TIP41 and its base 1N4007 prevent any
> reverse currents from the battery. If the battery has a shorted cell or is
> otherwise damagingly low, the TIP41 should come out of saturation allowing
> the S9013 to turn on and start diverting TIP41 base current etc until
> TIP41 is completely off and S9013 is saturated on. But that's a real rough
> HFE dependent threshold.
in the first of the links above in the OP, but R5 is actually 400 ohms and
not 400k. It also seems to be protected against reverse connection as you
describe. Here is the simulation with steps of battery voltage from 8 volts
to 16 volts 1/2 volt per step, then zero volts (short) and -12V (reversed
battery).
http://enginuitysystems.com/pix/electronics/HF_Float_Charger.png
And the ASC file:
http://enginuitysystems.com/pix/electronics/HF_Float_Charger.asc
Thanks,
Paul
bloggs.fred...@gmail.com
Nov 22, 2016, 11:22:35 AM11/22/16
to
Jim Thompson
Nov 22, 2016, 1:15:17 PM11/22/16
to
On Mon, 21 Nov 2016 14:24:41 -0500, "P E Schoen" <pa...@pstech-inc.com>
wrote:
Change the 7805 to an LM317 and adjust resistors accordingly.
The TIP41 circuit is weird.
Or simply toss most of it and change LM317 circuitry to a current
source arrangement... documented all over the web.
wrote:
The TIP41 circuit is weird.
Or simply toss most of it and change LM317 circuitry to a current
source arrangement... documented all over the web.
Jim Thompson
Nov 23, 2016, 2:56:58 PM11/23/16
to
the battery under the hood and follow a proper TC...
<http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
mako...@yahoo.com
Nov 23, 2016, 3:54:56 PM11/23/16
to
>
> If you want to do it right, locate the "charge-monitor" adjacent to
> the battery under the hood and follow a proper TC...
>
> <http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
>
>
but they are rather high for a 24/7 float charger.
m
P E Schoen
Nov 23, 2016, 11:58:47 PM11/23/16
to
makolber wrote in message
news:78210b20-df01-4d5c...@googlegroups.com...
The regulator in my 1989 Toyota truck probably is not very sophisticated,
and does not really apply to a float charger needed only because I often
don't drive it for weeks (even months) at a time. It is now charging with an
old Schauer 6-8 amp charger somebody gave me about 40 years ago - still
works fine - and stupid simple.
Here is some useful information if I decide to make my own high-tech battery
charger, using a PIC:
http://www.evdl.org/pages/hartcharge.html
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
http://batteryuniversity.com/learn/article/bu_214_summary_table_of_lead_based_batteries
http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge
http://batteryuniversity.com/learn/article/caring_for_your_starter_battery
http://batteryuniversity.com/learn/article/what_everyone_should_know_about_battery_chargers
Thanks for the information and discussion.
Paul
news:78210b20-df01-4d5c...@googlegroups.com...
and does not really apply to a float charger needed only because I often
don't drive it for weeks (even months) at a time. It is now charging with an
old Schauer 6-8 amp charger somebody gave me about 40 years ago - still
works fine - and stupid simple.
Here is some useful information if I decide to make my own high-tech battery
charger, using a PIC:
http://www.evdl.org/pages/hartcharge.html
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
http://batteryuniversity.com/learn/article/bu_214_summary_table_of_lead_based_batteries
http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge
http://batteryuniversity.com/learn/article/caring_for_your_starter_battery
http://batteryuniversity.com/learn/article/what_everyone_should_know_about_battery_chargers
Thanks for the information and discussion.
Paul
Jim Thompson
Nov 24, 2016, 10:10:27 AM11/24/16
to
On Wed, 23 Nov 2016 23:58:36 -0500, "P E Schoen" <pa...@pstech-inc.com>
wrote:
>makolber wrote in message
>news:78210b20-df01-4d5c...@googlegroups.com...
>
>> Jim Thompson wrote:
>>> If you want to do it right, locate the "charge-monitor" adjacent to the
>>> battery under the hood and follow a proper TC...
>>
>>> <http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
>>
>> those voltage might be OK for a few hours a day in a car alternator....
>> but they are rather high for a 24/7 float charger.
Wrong! They are the desired cell voltages at those temperatures.
My patents:
3,496,447 Alternator Voltage Regulator Responsive to Temperature
3,505,590 Temperature Responsive Output Voltage Apparatus
3,522,482 Temperature Compensated Voltage Regulation
3,546,563 Alternator Voltage Regulation Utilizing A Constant Current
Source
By the late '60's _every_ (*) American car manufacturer was using one
of my alternator regulator designs.
Ford, Chrysler, GM, and American Motors (Nash, etc, for you youngsters
;-)
I can't remember if Kaiser-Frazer was still existent, they aren't on
my list.
>
>The regulator in my 1989 Toyota truck probably is not very sophisticated,
>and does not really apply to a float charger needed only because I often
>don't drive it for weeks (even months) at a time. It is now charging with an
>old Schauer 6-8 amp charger somebody gave me about 40 years ago - still
>works fine - and stupid simple.
>
>Here is some useful information if I decide to make my own high-tech battery
>charger, using a PIC:
>
>http://www.evdl.org/pages/hartcharge.html
>
>http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
>
>http://batteryuniversity.com/learn/article/bu_214_summary_table_of_lead_based_batteries
>
>http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge
>
>http://batteryuniversity.com/learn/article/caring_for_your_starter_battery
>
>http://batteryuniversity.com/learn/article/what_everyone_should_know_about_battery_chargers
>
>Thanks for the information and discussion.
>
>Paul
A conventional battery charger will overcharge a battery if left on
indefinitely, because it provides a voltage well above cell voltage.
wrote:
>makolber wrote in message
>news:78210b20-df01-4d5c...@googlegroups.com...
>
>> Jim Thompson wrote:
>>> If you want to do it right, locate the "charge-monitor" adjacent to the
>>> battery under the hood and follow a proper TC...
>>
>>> <http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
>>
>> those voltage might be OK for a few hours a day in a car alternator....
>> but they are rather high for a 24/7 float charger.
My patents:
3,496,447 Alternator Voltage Regulator Responsive to Temperature
3,505,590 Temperature Responsive Output Voltage Apparatus
3,522,482 Temperature Compensated Voltage Regulation
3,546,563 Alternator Voltage Regulation Utilizing A Constant Current
Source
By the late '60's _every_ (*) American car manufacturer was using one
of my alternator regulator designs.
Ford, Chrysler, GM, and American Motors (Nash, etc, for you youngsters
;-)
I can't remember if Kaiser-Frazer was still existent, they aren't on
my list.
>
>The regulator in my 1989 Toyota truck probably is not very sophisticated,
>and does not really apply to a float charger needed only because I often
>don't drive it for weeks (even months) at a time. It is now charging with an
>old Schauer 6-8 amp charger somebody gave me about 40 years ago - still
>works fine - and stupid simple.
>
>Here is some useful information if I decide to make my own high-tech battery
>charger, using a PIC:
>
>http://www.evdl.org/pages/hartcharge.html
>
>http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
>
>http://batteryuniversity.com/learn/article/bu_214_summary_table_of_lead_based_batteries
>
>http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge
>
>http://batteryuniversity.com/learn/article/caring_for_your_starter_battery
>
>http://batteryuniversity.com/learn/article/what_everyone_should_know_about_battery_chargers
>
>Thanks for the information and discussion.
>
>Paul
indefinitely, because it provides a voltage well above cell voltage.
P E Schoen
Nov 25, 2016, 9:55:15 PM11/25/16
to
"Jim Thompson" wrote in message
news:b60e3c958q2sj8cve...@4ax.com...
> If you want to do it right, locate the "charge-monitor" adjacent to the
> battery under the hood and follow a proper TC...
> <http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
From the second graph, the ideal voltages seem to be:
Temp Vpc V12 Tempco
0C 2.49 14.95V
25C 2.47 14.80V -6 mV/C
50C 2.38 14.30V -20 mV/C
75C 2.32 13.90V -16 mV/C
100C 2.25 13.50V -16 mV/C
The information I found elsewhere was about as follows, for state-of-charge
after settling 3 hours:
SOC Vpc V12
100% 2.116 12.700
90% 2.083 12.500
80% 2.070 12.420
70% 2.053 12.320
60% 2.033 12.200
50% 2.010 12.060
40% 1.983 11.900
30% 1.958 11.750
20% 1.930 11.580
10% 1.890 11.340
0% 1.750 10.500
And my charging algorithm as originally conceived:
Initial charge at 0.2C for 5 hour nominal charge time for a 12 V, 12 A-h SLA
initial charge at 2.4A
Maintain charging until voltage reaches 2.4-2.5 Vpc = 14.4-15 VDC
At 14.4V battery is 70-80% charged
Keep at 14.4 volt until current = 0.02C (240 mA for 12 Ah)
Float charge at 12.8-13.2V (or initiate new charging cycle at 12.5 volts
(90%)
Voltages are based on 25C. Voltage changes by -0.003 Vpc/DegC. So 14.31V at
30C and 14.49V at 20C
>> those voltage might be OK for a few hours a day in a car alternator....
>> but they are rather high for a 24/7 float charger.
> Wrong! They are the desired cell voltages at those temperatures.
> My patents:
> 3,496,447 Alternator Voltage Regulator Responsive to Temperature
> 3,505,590 Temperature Responsive Output Voltage Apparatus
> 3,522,482 Temperature Compensated Voltage Regulation
> 3,546,563 Alternator Voltage Regulation Utilizing A Constant Current
> Source
> By the late '60's _every_ (*) American car manufacturer was using one of
> my alternator regulator designs.
> Ford, Chrysler, GM, and American Motors (Nash, etc, for you youngsters ;-)
> I can't remember if Kaiser-Frazer was still existent, they aren't on my
> list.
>
>> The regulator in my 1989 Toyota truck probably is not very sophisticated,
>> and does not really apply to a float charger needed only because I often
>> don't drive it for weeks (even months) at a time. It is now charging with
>> an old Schauer 6-8 amp charger somebody gave me about 40 years ago -
>> still works fine - and stupid simple.
That seems to be well below even the minimum of your charts (as well as I
could read them). And my SLA is reading 13.42 volts. So those seem to be
safe values. I find it hard to believe the "Ford limits" of 14.5 to 15.3
volts at about 20C. Even for fast charging (30+ amps) I would expect no more
than 14.4 volts under any circumstances. And the high temperature of 125C
(257F) seems way above any expected temperature that might be encountered
under the hood of a vehicle.
I'll have to read the patents for more information.
Thanks,
Paul
news:b60e3c958q2sj8cve...@4ax.com...
> If you want to do it right, locate the "charge-monitor" adjacent to the
> battery under the hood and follow a proper TC...
> <http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf>
Temp Vpc V12 Tempco
0C 2.49 14.95V
25C 2.47 14.80V -6 mV/C
50C 2.38 14.30V -20 mV/C
75C 2.32 13.90V -16 mV/C
100C 2.25 13.50V -16 mV/C
The information I found elsewhere was about as follows, for state-of-charge
after settling 3 hours:
SOC Vpc V12
100% 2.116 12.700
90% 2.083 12.500
80% 2.070 12.420
70% 2.053 12.320
60% 2.033 12.200
50% 2.010 12.060
40% 1.983 11.900
30% 1.958 11.750
20% 1.930 11.580
10% 1.890 11.340
0% 1.750 10.500
And my charging algorithm as originally conceived:
Initial charge at 0.2C for 5 hour nominal charge time for a 12 V, 12 A-h SLA
initial charge at 2.4A
Maintain charging until voltage reaches 2.4-2.5 Vpc = 14.4-15 VDC
At 14.4V battery is 70-80% charged
Keep at 14.4 volt until current = 0.02C (240 mA for 12 Ah)
Float charge at 12.8-13.2V (or initiate new charging cycle at 12.5 volts
(90%)
Voltages are based on 25C. Voltage changes by -0.003 Vpc/DegC. So 14.31V at
30C and 14.49V at 20C
>> those voltage might be OK for a few hours a day in a car alternator....
>> but they are rather high for a 24/7 float charger.
> Wrong! They are the desired cell voltages at those temperatures.
> My patents:
> 3,496,447 Alternator Voltage Regulator Responsive to Temperature
> 3,505,590 Temperature Responsive Output Voltage Apparatus
> 3,522,482 Temperature Compensated Voltage Regulation
> 3,546,563 Alternator Voltage Regulation Utilizing A Constant Current
> Source
> By the late '60's _every_ (*) American car manufacturer was using one of
> my alternator regulator designs.
> Ford, Chrysler, GM, and American Motors (Nash, etc, for you youngsters ;-)
> I can't remember if Kaiser-Frazer was still existent, they aren't on my
> list.
>
>> The regulator in my 1989 Toyota truck probably is not very sophisticated,
>> and does not really apply to a float charger needed only because I often
>> don't drive it for weeks (even months) at a time. It is now charging with
>> an old Schauer 6-8 amp charger somebody gave me about 40 years ago -
>> still works fine - and stupid simple.
> A conventional battery charger will overcharge a battery if left on
> indefinitely, because it provides a voltage well above cell voltage.
My battery is being charged at 13.85 volts at about 45C ambient (about 7C).
> indefinitely, because it provides a voltage well above cell voltage.
That seems to be well below even the minimum of your charts (as well as I
could read them). And my SLA is reading 13.42 volts. So those seem to be
safe values. I find it hard to believe the "Ford limits" of 14.5 to 15.3
volts at about 20C. Even for fast charging (30+ amps) I would expect no more
than 14.4 volts under any circumstances. And the high temperature of 125C
(257F) seems way above any expected temperature that might be encountered
under the hood of a vehicle.
I'll have to read the patents for more information.
Thanks,
Paul
Neon John
Dec 11, 2016, 3:31:06 PM12/11/16
to
On Mon, 21 Nov 2016 16:14:37 -0800 (PST), mrda...@gmail.com wrote:
>On that note, are there any good, reasonably-cheap SMPS 12V (14.4v?) battery chargers?
Sure, but you're going to pay more than HF prices. The "intelligent"
>On that note, are there any good, reasonably-cheap SMPS 12V (14.4v?) battery chargers?
chargers that Wal-Mart sells under the Black & Decker brand and Vector
at other places are very good. They execute a full 3 stage charge
cycle and then go into float/maintenance mode. Schumacher also makes
a good line.
A less intelligent charger made by Exide is also good. It doesn't do
the full 3 stage cycle but instead is a bistable charger. On to a
certain voltage and then completely off until the battery voltage
drops to a lower threshold.
These chargers (which use a transformer and bridge to feed the
comparator circuit board) do a good job. I have quite a few very
expensive AGM traction batteries left over from my playing with EV
days. I bought a bunch of these chargers because they were fairly
cheap and testing showed that they worked.
They've kept my inventory in excellent shape. Some are around 10
years old, yet test out to almost 100% capacity during a discharge
capacity test.
John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address
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