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Thread: How do i charge a LEAD ACID battery.

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    AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent AtomSoft Excellent
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    Default How do i charge a LEAD ACID battery.

    Hey guys i own a few of these:

    12-Volt/7Ah Lead-Acid Alarm Battery - RadioShack.com

    I want to know if someone can point me to some good info on how to charge it. Also any technical info would be awesome!!!


    Thanks in advance.
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    Something like :
    12 Volt 1 Amp Sealed Lead Acid Battery Charger: BatteryMart.com

    I want to make. I found:

    Charging the lead-acid battery

    Would it be safe to say i can just plug the battery in and monitor the voltage and test it against that chart?
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    jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent
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    Here are three good sources for not too technical information. The DOE also has a lengthy document on lead-acid batteries, but it is quite technical. As you read technical papers, you may may find reference to lead peroxide. That is actually a misnomer. The compound is PbO2. It can be referred to more accurately as lead dioxide or lead(IV) oxide (Pb(IV) oxide).

    Battery Chemistry Tutorial and FAQ from PowerStream: Custom battery chargers and power supplies for OEMs

    Deep Cycle Battery FAQ

    Welcome to Battery University

    The last two links discuss most battery types. You can search on lead-acid batteries.

    Chargers are quite plentiful, as you know.

    John

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    Quote Originally Posted by AtomSoft View Post
    Hey guys i own a few of these:

    12-Volt/7Ah Lead-Acid Alarm Battery - RadioShack.com

    I want to know if someone can point me to some good info on how to charge it. Also any technical info would be awesome!!!


    Thanks in advance.
    You can float charge it continuously from a regulated DC voltage of about 13 - 13.2V.
    Last edited by bountyhunter; 4th October 2009 at 11:41 PM.

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    wow lead acid seems really simple to charge.

    I just mainly have to monitor voltage levels and keep a steady voltage until it reaches a certain level (voltage) then remove power or stop charge until it drops and when it does just turn charge back on.

    This way i can leave it charging for a long time and not have to worry about the discharge issue.

    Ok now for the technical part. Ill make a new topic in Micro section...


    Thanks guys!!!!
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    k7elp60 Excellent k7elp60 Excellent k7elp60 Excellent k7elp60 Excellent k7elp60 Excellent
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    You can float charge your battery @ 13.5 to 13.8V with the charger connected at room temperature and never overcharge the battery. Powersonic in their technical data book recomends that the charge current be limited to 0.2 times the capacity. For you 7AH battery that would be 1.4 amps.
    I have been building chargers for 12 7AH gel-cel batteries for more years than I can remember. If you would like to build one I can post schematics for several different ones. One uses a LM317T, another one uses a PB137 IC that was designed for that purpose. This one requires no adjustment with a DVM.
    The LM317T one has an added circuit that senses when the battery is charged and turns on an LED with the battey is charged. This one requires two adjustments, one for charge voltage and one for charge indication.
    The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
    Show me a different way. I have an open mind.

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    Quote Originally Posted by AtomSoft View Post
    wow lead acid seems really simple to charge.

    I just mainly have to monitor voltage levels and keep a steady voltage until it reaches a certain level (voltage) then remove power or stop charge until it drops and when it does just turn charge back on.
    Nope, that's not the best way for lead acid. You keep the charger on all the time and just hold the battery voltage at 13 - 13.2V. That prevents sulphation. Letting a lead-acid battery sit with no charging going on can lead to death over time.

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    Quote Originally Posted by k7elp60 View Post
    You can float charge your battery @ 13.5 to 13.8V with the charger connected at room temperature .
    I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

    Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging.
    http://www.solarnavigator.net/battery_charging.htm
    Last edited by bountyhunter; 5th October 2009 at 08:36 PM.

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    Quote Originally Posted by bountyhunter View Post
    I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

    LEAD ACID BATTERY CHARGING INFORMATION, BATTERY TYPES AND OPERATION - SOLAR NAVIGATOR WORLD ELECTRIC NAVIGATION CHALLENGE, NELSON KRUSCHANDL, BLUEBIRD ELECTRIC LAND SPEED RECORD CARS
    I base my remarks on the attached PDF, page 10 to be specific.
    Attached Files
    The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
    Show me a different way. I have an open mind.

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    I have a hunch that AdamSoft wants to charge dead lead-acid batteries that are suphated because they have been discharged (due to self-discharge) for years.

    It ain't gonna happen. The batteries are ruined.
    Uncle $crooge

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    Here are the DOE documents I mentioned earlier. They are lengthy. DOE spends billions a year, so get your money's worth.

    In this document, there is a nice table on page 20 (of the document, not pdf page) that tells about float charging.

    This document describes some of the dangers of overcharging, including production of poisonous gases from batteries that have been modified with antimony, tin, and/or selenium.

    I agree with AG. If you are trying to bring back to life batteries that have sulfated, forget it. Also, if the batteries you are dealing with are "sealed," some of the maintenance procedures, particularly with respect to float charging, are different than for flooded, open lead-acid batteries. The DOE documents discuss both types.

    John

    John

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    Quote Originally Posted by k7elp60 View Post
    I base my remarks on the attached PDF, page 10 to be specific.
    Yeah, there is a divergence of recommendations for float charging. I have had best luck with keeping the voltage at the more conservative end (13.2). Float charging at 13.8V probably won't kill a battery, but it does increase gassing compared to 13.2V and I personally don't think you need to do it.

    I suspect they went to a higher recommended voltage so that the chargers don't have to have built-in temp compensation. Lead acid 12V batteries have approximately -20mV/C tempco and the charger should track that. If it doesn't, the battery can be undercharged at cold temps where the battery voltage goes up but the charger doesn't follow. I use temp compensation on my charger so I can set it just a shade over the voltage it takes to keep the battery peak charged and I know it will always be right regardless of temp. Anyway, it's worked well for 25 years.
    Last edited by bountyhunter; 5th October 2009 at 11:47 PM.

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    Quote Originally Posted by jpanhalt View Post
    Here are the DOE documents I mentioned earlier. They are lengthy. DOE spends billions a year, so get your money's worth.

    In this document, there is a nice table on page 20 (of the document, not pdf page) that tells about float charging.

    If I read page 20 right:

    Cell Float Voltage

    (2.15-2.17) volts PbSb
    A "12V" battery has six cells, so it would come out to 12.9V - 13.0V for float charging. That's probably what I was remembering when I recommended 13 - 13.2V initially.

    It is slightly different for a different battery type:

    (2.17-2.25) volts PbCa
    Which would be 13.0V to 13.5V
    Last edited by bountyhunter; 5th October 2009 at 11:55 PM.

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    heh these are brand new batteries. I own 2 and i had a few customers come into my job at radio shack asking me where to get a charger and why dont we sell them.

    So i decided to buy a couple and try to make a charger on my own and see how much it cost compared to commercial chargers then if possible create them and sell them outside/apart my job. Will be sold with no warranty/guarantee and has nothing to do with my job. I will sell it as cheap as possible while trying to make the money back from parts and something for time spent reading and learning this myself.

    13v was my main choice. The batteries i have like a IDIOT i threw away the boxes which had a ton of info on them heh

    Ill go and make a photo copy of the box at work and show you all along with my idea of how to charge it and my method and schematic and source etc...
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    Quote Originally Posted by bountyhunter View Post
    I think 13.8V is good for a car battery's charging system where you want to replace lost charge quickly, but it's a bit too high for continuous float charging. Check the manufacturer's spec sheet, they always recommend a lower cell voltage for float charging. I use 13.2V for my motorcycle charger to keep it charged all year round and I get about 8 - 10 years life out of the batteries. Float charging to a higher voltage like 13.8V will boil the water out faster and require more topping off.

    LEAD ACID BATTERY CHARGING INFORMATION, BATTERY TYPES AND OPERATION - SOLAR NAVIGATOR WORLD ELECTRIC NAVIGATION CHALLENGE, NELSON KRUSCHANDL, BLUEBIRD ELECTRIC LAND SPEED RECORD CARS
    NICE!!! thanks for link!
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