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Thread: Sealed Lead Acid Battery's -- Trickle Charging, and Charging.

  1. #1

    Default Sealed Lead Acid Battery's -- Trickle Charging, and Charging.

    Group,

    I am trying to setup a battery charger for Sealed Lead Acid battery's, and am curious about how to go about it. I'm hoping someone can point me in a direction of some good reference documents on the internet, I havn't been able to find any of them.

    Also, I have a trickle charger that is designed for a Seal Lead Acid battery, but it's designed for a 12V 7AH battery, will this charger work for my 4 AH sealed lead acid battery? I would assume that the charger measures simply by voltage, therefore it would charge any size seald lead acid battery, but I wanted someone else's thoughts on it before I go charging stuff that's not designed for it. Even if this charger would work, I am still needing to build my own circuit for charging one.

    The reason I need my own circuit is because I want to charge up a Sealed Lead Acid battery from a set of three solar panels. And the voltage on these will be something like 17 volts, at max.

    Knight.

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    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  2. #2

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    A lot of poorly designed things will charge a battery, but they cut into the 'fullness' of the charge or the life of the battery.

    Generally, the substantial difference between 4 AH and 7 AH at the same voltage will call for a different rate of charge. Usually that refers to 'fast charge' which really can cause overheating and severe damage from too high a rate. The flip side is whether there is an ideal or too low a rate for a 'trickle charge'.

    Read the Art of Electronics on batteries as a background.

    I guess you should just put an amp meter on the trickle charger and determine what the trickle really is. It is likely to be fine [maybe a bit on the high side, but nothing extreme]. Trickle chargers imply 'no shut down' or continuous use. So 40ma at 12volts equals .48watts. If it is not used in charge up, it is dumped in heat. That is all. Imagine touching a 50watt light bulb versus a half watt bulb and you can imagine the dilema. The acid is cooking a bit inside the battery. The less it cooks, the better. Of course, if the battery is stored at 32 degrees F or lower, you may want to keep it warmer via trickle. [You car has trouble starting when the battery is too cold, right?]

    So, the environmental temperature range has something to do with what you want. You might even program a tickle charger for various ambient temperature environments.

    The other question of voltage.
    You usually want to keep the voltage down to a reasonalbe level as it drives additional overheating. 17 volts to charge 12 volts is a bit high. I think 13.2volts is the usual target, but see if you can get some manufacturer's specs. That extra voltage [3.8volts] times the amperage is wasted power: again I X V=Watts.

    And the heat is dumped either inside the battery or somewhere along the line.

    Again, it you have a freezing, sunny day - you may want the 17 volts to keep the battery warm.

    If you cannot get a good component fit -- It might be more useful to drive a pilot light [a series of low voltage lights or even rectifier diodes to bring down the Voltage] than to put the heat generation into the battery where it will shorten the batteries life.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ииииииииииииииииииииииииииииииииииииииииииииииииии ииииииииииииииииииии Warm regards,иииии G. Herzog [и黃鶴 ]иin Taiwan
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  3. #3

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    www.uuhome.de/william.darden/
    The link above is a pretty good link for general information on batteries.

    In the end, check with the manufacturer to determine how it wants to be charged.

    You basically have 2stages of charging (and can buy $$ chargers to do this automatically)....the first is a rapid charge to bring up a 'low' battery.
    Then it usually switches to a trickle or float charge to keep things at the charge level.

    On wet cells, you end up getting a lot of deposits on the plates which reduces the amount of charge/energy the battery will hold. So, sometimes, a way to 'revive' an old wet cell is to 'EQUALIZE' it. This is basically a hard charge that will dispel the desposits back in to the electrolyte (wet solution). This doesn't always work, and shouldn't be left on for a long time or, as Kramer pointed out, you will be boiling your battery and if you can't add fluid then it's pretty well useless once it boils off!

    Again, check the manufacturer and the link I put in. It used to be called 'batteryfaq.org' but all I got was a mirror site, so hopefully it still has all the info on there!

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    и

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  4. #4

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    Actually your Sealed battery should have a datasheet from the maufacturer. Who is the maker?

    I have a few sealed lead acid, one is a power sonic and has datasheets with the exact required recharge info.

    Chances are pretty good that if you can FIND someone who makes a 4AH 12volt sealed lead acid battery that it will require the exact same or very similar charge characteristics.

    I ended up buying a charger for my batteries because the parts to do the same thing were about the same price.
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  5. #5
    Parallax Engineering

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    Default

    knightofoldcode said...(trimmed)
    I am trying to setup a battery charger for Sealed Lead Acid battery's, and am curious about how to go about it. I'm hoping someone can point me in a direction of some good reference documents on the internet, I havn't been able to find any of them.
    Also, I have a trickle charger that is designed for a Seal Lead Acid battery, but it's designed for a 12V 7AH battery, will this charger work for my 4 AH sealed lead acid battery? I would assume that the charger measures simply by voltage, therefore it would charge any size seald lead acid battery, but I wanted someone else's thoughts on it before I go charging stuff that's not designed for it. Even if this charger would work, I am still needing to build my own circuit for charging one.
    Knight,

    ии Tracy Allen once guided me to a chip which can help facilitate charging of SLA batteries.и While my move out here has prevented me from actually conneecting everything as suggested, I would definately trust Tracy's suggestion and will get to this soon.и Have a look at the following charging regulator.и I bought 5 of these to try on my SLA Battery.и Of course, I believe mine is 7mAh, but I don't think it matters based on what I was told.

    http://www.emesystems.com/pdfs/parts/PB137.pdf

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  6. #6

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    Kramer said...
    A lot of poorly designed things will charge a battery, but they cut into the 'fullness' of the charge or the life of the battery
    Agreed,
    и
    For Lead acid batteries, I have always heard that a pretty sound "float" charger is to place a LAMP in series with
    your charging supply.и Select a lamp with a current rating that you desire to charge the battery at.и In theory,
    with a low battery there will be a higher voltage differential across the lamp and it will "light" causing the filament
    in the lamp to heat up, increasing resistance in the filament, thus limiting (self regulating)иthe amount of current
    to the battery being charged.и As the battery charges, the voltage differential across the lamp decreases and it
    eventually extinguishes.ииThe lamp also serves a purpose of allowing an alternative route for excess energy (heat)
    to escape from the system rather thanиfrom the battery alone.
    и
    This can be demonstrated by connecting two dc motors in series and powering both of them.и Call motor "A" the
    battery, and motor "B" the lamp (<- or current regulator).и If you stall motor "A" (the battery in opposition to wanting
    a charge), motor "B" allows the energy to be diverted from motor "A" with minimal heat increase due to stalling.
    и
    и


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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  7. #7

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    For most current SLA bricks, trickle charging is not recomended, when the battery is full the charger will continue to try to charge it. This can cause damage to the battery, reducing its AH rating over time. I purchased a current state of the art charger for my SLAs (cost $50), and it has 3 zones of charging, the first is constant current, the second is constant voltage, and the third is shutoff, the determination of which zone the charger is in is dependent on the present capacity of the battery, these type of chargers are sometimes refered to as intelligent chargers.

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    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  8. #8

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    If the demands on the battery will be light, you can get by with a float charger. Float charging is appropriate in a system where only a small fraction of the battery capacity will be used in a day and there is ample sunlight and panel capacity to restore that energy. A fast charger (2 or 3 stage, intelligent) is necessary where the load on the battery is heavy and where it is necessary to charge the battery as fast as possible between uses. Examples of light use would be a burglar alarm or a data logger. Examples of heavy use would be a pump or a solar car.

    A fast charger allows the battery terminal voltage to rise to around 14.3 volts, and the charger has to monitor and limit the current, and it has to switch back to the 13.7 volt float level when the battery stops accepting current. Overcharging can deplete the electolyte with bubbling off of explosive gases, shorten the life of the battery.

    A float charger is basically a voltage regulator that limits the input voltage to a certain value, about 13.7 volts at room temperature for a nominal 12 volt sealed Pb-acid battery. That is the function of the PB137 charger IC that Chris mentioned. It is essentially a 13.7 volt regulator with the added feature that it does not discharge the battery when the input power is disconnected (as it would be from solar panels at night!). The PB137 does require a few externnal components, a capacitor, and polarity protection if there is any danger of someone connecting the battery or the power source backwards. The Pb137 supplies up to 1.5 amps. Most battery manufacturers now claim that there is no need for current limiting in a float only system. The batteries self limit. So, the same chip would be okay to float charge any AH capacity battery. The PB137 is not really well suited to use with solar panels. The input voltage has to be about 2 or 3 volts higher than the input (so 16.5 volts input for 13.7 volts output). That may be the full sun output of your solar panels and not their point of maximum efficiency, and especiallhy inadequate in dim winter light. But the PB137 is a very neat solution when the condditions are right.

    The proper float voltage depends on temperature. The Pb137 is meant for use at around room temperature. The best float voltage ranges from 15 volts at -25 degrees C, to 13.1 volts at +60 degrees C. Those extreme temperatures could be encountered in a system housed in a box outdoors all year. The PB137 does not compensate for temperature. In my data loggers for float charging I use a circuit based on the LT1129 low dropout regulator (So it will work efficiently with minimum sunlight), with a thermistor for temperature compensation, and protection against miswiring.

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    Tracy Allen
    www.emesystems.com
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  9. #9

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    KNIGHT,

    MAY I SUGGEST THAT PART TIME YOU USE OR "HACK INTO AND USE THE CIRCUIT" .

    SURCHARGE IV

    http://www.vdcelectronics.com/surechargeiv.htm

    WHY?

    SURECHARGE IV USES PULSE CHARGING WHICH HELPS TO PREVENT, REDUCE AND EVEN ELIMINATE SULPHATION WHICH IS THE GREATEST ENEMY OF LEAD ACID CELLS..

    NORTHERN TOOL OS ONE SOURCE I KNOW OF. I HAVE BEEN USING THEM FOR YEARS AND THEY WORK GOOD.

    73
    SPENCE
    K4KEP
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  10. #10

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    Well, the 'sealed' aspect really brings home the need to have a phase that shuts down the charge to at least reduce pressure buiild-up. It may enhance the chemistry as well.

    You cannot really justify a continuous trickle charge as being optimal to battery life or safety in sealed cells.и That PB137 looks like the best for an 'indoor' system, but where does one get solar indoors?и As far as temperature, unless you live in San Francisco you are likely to have at least one if not both extremes to manage in an outdoor setup.и The cold side may be more easily fixed by a bigger battery to pull the charge out of.и It doesn't have the phase change from liquid to steam.

    Back in the days of the Stanley Steamer, everyone was quite interested in the fact that steam can take on an infinite amount of energy. Then they found that building a pressure release system was a lot harder than building a boiler. Many steam heated buildings have switched over to electric baseboard because of the hazard of explosion demonstrated by earlier failures.

    Any sealed battery presents the same dilemma. With the BasicStamp, you might include a thermal shutdown and a timed cycle shut down. Or you can likely do very well with a specifically designed chip for battery charge.

    What you see is that engineering keeps getting more and more subtle in the issues of design and use. If you want to walk away from a solar charger for three months to a year, you have to nurse the battery as if it were gold. If you want to be away for a weekend, you don't have to be so perfect. Just imagine what is done to assure battery life on a device that is sent into deep space. That is where we got all this from.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ииииииииииииииииииииииииииииииииииииииииииииииииии ииииииииииииииииииии Warm regards,иииии G. Herzog [и黃鶴 ]иin Taiwan

    Post Edited (Kramer) : 11/9/2005 2:54:33 PM GMT
    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  11. #11

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    Thank you for all the responces, I know for a fact that everyone has a different opinion on how to take care of a battery.

    My brother, who is a EE, tells me things that I've read different on packages, so whose right?

    Anyways, I appreciate all the information.

    The application of this would be two of them. First one would be for a alarm system, and that one should obviously be indoors, so a use of the IC mentioned above by Tracy Allen is what I'll go with for THAT situation.

    The second implementation is that I intend to have 75watts of solar panels lining the top of my work "truck", it's actually a suburban. I use alot of tools but only occasionally. A power drill here and there, but I want everything to be charged when I want to use it....

    I've already designed a Basic Stamp controller that would turn on a 110 AC power inverter running off of my solar powered 12 car battery (it's in a battery box and vented to the outside so no bad fumes) and the basic stamp basically turns on/off some 110 AC outlets, which have the cargers for all of the devices on it.

    In other words, above each devices outlet there is a button, and that button is the "charge" button.... Dip switches set hte amount of time for a charge, So a drill could be 6 hours, and a flashlight 1 hour, etc. Once the button is pressed the basic stamp turns on the inverter, and waits for 1 hour, after an hour if that's there is no other items needing charging, it shuts off the inverter, otherwise it leaves the inverter on, and jsut shuts off that particular device's charger.

    I had orginally plugged it into my shop with just plain 110VAC, but it's really inconvinient to have to disconnect before driving off.... I have forgotten to unplug 3 times...... Luckily I designed it so it would just pull out and not damage anything, but it did leave the cord dangling and the road damaged the plug. :(

    As for the work truck application, I did find a solar panel charger that is designed for this purpose, (wasn't hard, the hard part was finding one that was cheap), I have finally found one that is cheap. $30 and it works for up to 100watts of panels, so it's probably going to work well. (on order) :)

    BTW, this truck is used maybe at MOST once a week?... Probably less than that. I bought it just for picking up other vechicles int he family that had died for any reason and taking them back to my shop to be repaired, so it just has to have a basic set of tools running off this battery.

    Knight.

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    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

  12. #12

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    Someone else from these forums sent me a private message with some additional information and I thought I should share it incase someone else comes across this same kind of information needed.


    www.uoguelph.ca./~antoon/circ/bcgla.htm


    Knight.

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    -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-
    This message transmitted with 100% recycled electrons.
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    Gravity doesn't exist. The Earth sucks.
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    Make a man a fire, and he will be warm for the night.
    Light the man on fire, and he will be warm for the rest of his life.
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    Last edited by ForumTools; 10-01-2010 at 04:52 PM. Reason: Forum Migration

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