Author Topic: 12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger  (Read 3489 times)

sonickay

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12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger
« on: November 13, 2013, 05:38:00 AM »
Good day everybody. I have been running through forums and posts helter-skelter just to find the right ideas and inexpensive components to build a DIY, use at home, 12volt 7Ah battery charger for a similar battery Martin used in his DMM Multimeter Tutorial when testing Amps.
So far I have ruffled through many posts which I can't make head or tail with; the components are either expensive, complex or not working properly as evidenced by comments from members. This has left me confused and dazzled at a moment I need the battery to further my electronics tutorials, I don't want to waste my money and time especially during a period I need to charge the battery at home without running to a "Batterier" (Commercial Battery Charging Shops) every now and then.
I have written to Martin about this but he said he coulšnt help personally, I guess he has been very busy. So he advised me to post in the forum for way forward and receive ideas from other forum contributors. I will be guided with your ideas on how you charge your 12volt battery optimally and inexpensively ASAP.
Thanks.

MJLorton

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Re: 12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger
« Reply #1 on: November 19, 2013, 11:40:18 AM »
Hello Sonickay,

Have a look at this and see if it will do the job:
http://www.instructables.com/id/DIY-Lead-Acid-Battery-Charger/

Cheers,
Martin.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)

SeanB

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Re: 12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger
« Reply #2 on: November 19, 2013, 01:25:44 PM »
That will work, but if you are strapped for cash find an old burglar alarm or such that uses a SLA battery of the type you want to charge and remove the charger from inside it, or use it as is as a charger only.

sonickay

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Re: 12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger
« Reply #3 on: November 20, 2013, 02:29:57 PM »
Thanks Martin and Sean for the contributions. I have been able to make do with a make-shift charger I built using a 16volt AC transformer, a bridge rectifier and some 1000farads capacitor. The net output from the configuration is 16volts DC 500mA. I risked running down the battery life over time but It serves me well in its little way even though I ought to have at least 700mA for ideal charging. Thanks a lot...

SeanB

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Re: 12Volt 7Ah Valve Regulated Sealed Lead acid Battery Charger
« Reply #4 on: November 20, 2013, 03:10:19 PM »
You do not really need the capacitor, just a resistor to limit current into the battery and a voltmeter to monitor voltage so you can disconnect the charger when the battery voltage reaches 14.4V so it is not overcharged. at 500mA you will take around 15 hours to charge the battery from flat. If you only discharge partially it will take less time.  If you can get a regulated charger or build one that puts out 13.8V then you can float charge the battery all the time without any issues.