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Message |
    
Ohiobiker
Member
Username: Ohiobiker
Post Number: 91
Registered: 12-2001
| | Posted on Friday, November 12, 2004 - 7:44 pm: | 
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I have a small power supply that plugs in the wall, like would power a small radio. It is rated at 117VAC-in and 13.5VDC@3amps. My question is this: If I want to use it as a trickle charge on a 12VDC battery like in my car or deep-cycle battery. Can it be used a is? or Do I need to put something in line to use it as such?
Thanks "OHIOBIKER" "575" Walter |
Dindin
Intermediate Member
Username: Dindin
Post Number: 435
Registered: 2-2004
| | Posted on Friday, November 12, 2004 - 7:55 pm: |
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Ohiobiker,the power supply could be used for a charger but if you plan to leave it connected for extended periods of time then the output needs to be reduced.this can be accomplished simply by putting a 6.8 to 10 ohm,10 watt resistor in one of the charger leads.be sure to cycle the battery ocassionaly to avoid plate sulfation. |
Bruce
Senior Member
Username: Bruce
Post Number: 1759
Registered: 9-2003
| | Posted on Friday, November 12, 2004 - 8:31 pm: |
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OR .......
I like using a small lightbulb like a #47 but you would have to choose the bulb based on the current need of the battery .... a 7 amp houre battery should charge at about 700 MILIAMPS MAX AT DISCHARGED BATTERY STATE and it should be safe. |
The ELCO guy (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, November 13, 2004 - 6:55 am: |
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Morning Bruce....
Might I suggest that you acquire a battery charger at the local auto parts store that has a trickle charger with auto shut off feature. This way you can be assured that not only the battery will be charged, also that once charged it will not be over-charged.
That Elco Guy |
Highlander
Advanced Member
Username: Highlander
Post Number: 676
Registered: 12-2001
| | Posted on Saturday, November 13, 2004 - 7:53 am: |
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I agree with elco guy--I have ruined many a battery by over-charging them.
David
n9rzf |
That Elco guy (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, November 13, 2004 - 3:01 pm: |
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Re Bruce...
Just curious why the need for the battery? Did you join a RACES or an ARES group? |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, November 14, 2004 - 4:25 am: |
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It would be nearly impossible to harm a lead acid battery large enough to be a car battery or a deep cycle battery with a power supply of 13.5v @ 3A as long as the plates are covered with electrolyte. Once the voltage of the battery reaches 13.5v there would be no current flow so it would not overcharge. Whether the battery is fully charged at this point depends on the capacity, temperature, and charge characteristics of that battery.
The charging system in most cars is regulated at 14V to keep the battery fully charged. Most car batteries eventually die because of undercharge - not overcharge. The plates sulfate during a state of discharge and when the battery is brought back to full charge the sulfation is dropped from the plates. Eventually this weakens the structure and a plate fails causing the battery to be unusable.
If you are planning to use the battery inside your home then the most critical factor is to make sure that you are not charging the battery to the point where it produces hydrogen gas - outgassing. A lead acid battery will outgas faster when it is colder because it then has less capacity. I'd watch the battery cells for a steady stream of bubbles when it reaches the power supply's regulated voltage - if it's not a maintenance free battery and you can pop the covers off and watch the cells. If you see the steady stream of bubbles then it is outgassing and you should drop the voltage of the power supply until it doesn't outgas.
If the battery has good ventilation then I'd want it to bubble a little at voltage because it's healthy for the cells to do so - just not too much because you're wasting electricity with each bubble. Outgassing is not bad for a lead acid battery - in fact it is a good thing to do on occasion in a controlled overcharging process called "equalizing the cells." Basically it removes any sulfation that forms on the battery's plates and makes the cells in the battery perform equally.
If you'd rather not worry about it, you can buy a charger that will keep the battery fully charged without outgassing. Some chargers also pulse charge the battery and this process removes the sulfation from the plates without the need to "equalize the cells" by controlled overcharging. |
Ohiobiker
Member
Username: Ohiobiker
Post Number: 92
Registered: 12-2001
| | Posted on Tuesday, November 16, 2004 - 1:54 am: |
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Thank Guys All the info is quite usefull, I have the batterys as a back up system basicly to power my radio, scanner and a few other items durring power failure. Living out in the country we tend to lose power durring some of the major storms. Yes I am aware of "outgassing" dangers. I also use the batterys from time to time just to keep them in shape, discharing them occasinaly and then recharging them so as to keep them worked and in good shape. Thanks to all who answered.
OHIOBIKER..."575"...Walter |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Tuesday, November 16, 2004 - 2:07 pm: |
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Discharging lead acid batteries doesn't keep them in shape - it only damages them. When the voltage drops below a certain level sulfation starts to accumulate. Sulfation is actually lead sulfate. The lead comes from the battery's plate. When the battery is charged again the lead sulfate is dropped from the plate to the bottom of the cell. Eventually this action will cause the plate to be damaged and it will fail. Deep cycle batteries have very sturdy plates to tolerate this action, but car batteries do not. Their plates are manufactured to facilitate high amperage surges of power for starting. The plates are a lot like a lead sponge to have maximum surface area. Just a little sulfation will damage a car battery and it will quickly fail.
It's best to keep a lead acid battery fully charged at all times. Occasional and controlled overcharging will keep it working well, but you only want to do that with a battery that allows you to maintain them by adding distilled water to the cells. Maintenance free batteries don't like to be overcharged often because it reduces the level of electrolyte and eventually leads to plate failure.
The best deep cycle batteries are used for storage in an alternative energy home, but they are very expensive, large, heavy, and more than you need. Probably the best batteries for your needs are golf cart batteries. They are made to be deep cycled and their construction is excellent - much better than a marine deep cycle battery. Some are 12v, but most are 6v and you'll need to put a pair in series.
To save some money, you can buy used golf cart batteries at salvage yards and get them to work again. Most are tossed after a certain duty cycle or because they won't take a charge anymore - not because they are physically damaged. They can be brought back to nearly new capacity in a couple of ways. There are sophisticated chargers that remove sulfation by pulsing a weak charge current. This actually returns the lead from sulfation back to the plate! There is also a chemical treatment that you can use in conjunction with a heavy charge current that will remove the sulfation from the plates, but afterward it is normally necessary to drain the elctrolyte, flush the cells, and then fill them with new electrolyte - aka sulfuric acid. There are many people who have done this as a cheap way to get deep cycle batteries for their first alternative power storage system.
Good luck! |
Highlander
Advanced Member
Username: Highlander
Post Number: 681
Registered: 12-2001
| | Posted on Tuesday, November 16, 2004 - 7:12 pm: |
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That's great information, thanks, Racer X.
Another point that should be stressed about using these batteries in the house is safety. Make sure there is no possibility of the battery(s) getting shorted on something. I've seen people who got hurt by exploding batteries, it isn't nice. Some people make a ventilated box to house them in.
I'm interested in setting up a wind generator and 12-volt storage system, and converting some of my lighting to 12 volt. Anyone know a supplier of the stuff I would need for 12 volt lighting systems?
David
n9rzf |
Tech808
Moderator
Username: Tech808
Post Number: 4100
Registered: 8-2002
| | Posted on Tuesday, November 16, 2004 - 7:24 pm: |
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Highlander,
Check the Forum for a post Tech833 made in the last week or so as he has Solar Power and storage for his house and equipment and can help you locate the things you need and where to get it.
Or make a Post to Tech833 as I am sure he can help you.
Lon
Tech808
CEF808
N9OSN |
Racer X (Unregistered Guest)
Unregistered guest
| | Posted on Tuesday, November 16, 2004 - 11:22 pm: |
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Highlander - check out the website for Home Power Magazine. The publisher is a radio guy - gotta appreciate that. |
Chad
Junior Member
Username: Chad
Post Number: 14
Registered: 11-2004
| | Posted on Wednesday, November 17, 2004 - 8:37 am: |
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Highlander, You could always go with low-volt halogen but this is far from efficient. I would consider LED. Take a gander at this site
http://www.ledtronics.com/
LED's will give you incredible burn time per charge and excellent lamp life, They have it dow now so that the color rendering is good also.
Chad
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S2art
Junior Member
Username: S2art
Post Number: 19
Registered: 2-2004
| | Posted on Wednesday, November 17, 2004 - 12:20 pm: |
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If you are looking for a backup power supply / trickle charger this is what I did. The company I work for uses lots of ups (uninterruptible power supplies). When they die, it costs more to replace the internal batteries then to replace the entire unit. We now have what I affectionately call MT.UPS in the back part of the building. Of coarse, with permission I now am in possession of several of these. Most of these units work off 12 volts. I removed the old dead batteries and soldered on a heavy-duty power connector I fed out the back. In the internal battery compartment, I mounted a small fan that kicks on when the ups is activated. A small car battery can power my security VCR and camera for at least 8 hours. When the unit sits idle, the ups serves as en excellent smart trickle charger. Another unit doubles for my 667 12 volt supply / computer UPS. Also some of the units have an annoying alarm that goes off when the power goes out (like I can’t figure that out for myself when the lights go out) Nothing a little selective surgery can’t fix. |
Highlander
Advanced Member
Username: Highlander
Post Number: 682
Registered: 12-2001
| | Posted on Wednesday, November 17, 2004 - 2:14 pm: |
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Thanks guys, between you and Google, I have plenty to soak up...
David
n9rzf |
