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Is there any disadvantage using an 18V 2A transformer with an adjustable DC-DC buck converter(link below) to charge a 12v 7Ah battery ?

I know that the charging current must not exceed C/10 (700mA here) and maximum voltage per cell shouldn't exceed 2.4V .

I guess the amount of current flowing into the battery should be proportional to the voltage difference between the charger and the battery. So i am planning to charge with a lower voltage initially like 13.6 V and gradually increase the to 14.1 V during the course of charging.

The Reasons for considering DC-DC buck converter is it's low cost and high efficiency. Lead acid battery chargers available here cost anywhere around 4 to 10 times more than this setup.

Buck converter (3A max): http://www.ebay.in/itm/LM2596-DC-DC-Buck-Converter-Step-Down-Power-Module-/201086952147?_trksid=p2054897.l5658

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  • \$\begingroup\$ would the negative voters care to comment ? \$\endgroup\$ – Ryu_hayabusa Dec 6 '15 at 8:26
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Spend a bit more and buy the version with a built-in current adjustment.

eg: http://www.aliexpress.com/item/High-Quality-5A-DC-to-DC-CC-CV-Lithium-Battery-Step-down-Charging-Board-Led-Power/32388356240.html (free shipping to most of the world - but not india)

http://www.ebay.in/itm/XL4015-5A-CC-CV-Lithium-Charger-DC-DC-Step-Down-Adjustable-Buck-Power-Module-/161879398799?hash=item25b0c3998f:g:JwYAAOSwhcJWOwOE (similar product on ebay india)

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The disadvantage is obvious: you have to babysit it or make a control circuit to do the adjustments for you... which is exactly what a dedicated charger [IC] does.

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  • \$\begingroup\$ Thanks for the answer, Any other disadvantage than the above mentioned one? . Also can you suggest a good charger IC ? \$\endgroup\$ – Ryu_hayabusa Nov 17 '15 at 5:39
  • \$\begingroup\$ I am planning for a smart charger, so i don't have problem with controlling voltage programtically. hackaday.com/2015/08/19/… \$\endgroup\$ – Ryu_hayabusa Nov 17 '15 at 5:45
  • \$\begingroup\$ Spend a bit more and buy the version with a built-in current adjustment. \$\endgroup\$ – Jasen Nov 17 '15 at 5:54
  • \$\begingroup\$ @Ryu_hayabusa: don't you think this latter info was essential to include in your question? \$\endgroup\$ – Fizz Nov 18 '15 at 20:41
  • \$\begingroup\$ @RespawnedFluff Not necessary, i just want to know, if it possible to do so. I have only basic knowledge in electronics. \$\endgroup\$ – Ryu_hayabusa Nov 20 '15 at 1:28

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