Hi Guys
If time is not a problem for me, can I charge a discharged car acid battery only with float charge ?
Thanks

 

Unlikely it will fully charge, a float charge is used to maintain a fully charged battery. The float voltage is typically lower than the voltage needed to fully charge a lead acid battery.
http://batteryuniversity.com/index.php/learn/article/charging_the_lead_acid_battery

 

Welcome to AAC!

You could, but it's not the correct way.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

EDIT: I see @nsaspook beat me by a few seconds...

 

Thanks guy for your reply
To make a story short, I'm trying to salvage my laptop power supplies and make them become an acid battery charger. I bought a dc to dc step down converter which I can adjust voltage and current. I'm just too lazy to set the converter to 14.5V for charging and then when it's fully "charged", I set it back to 13.5V for maintain. This is the reason why I ask you guys if my acid battery is still get charged if I leave my converter to 13.5V (float charge voltage).

 

Buy (or build) a proper multistage charger. Treat your batteries well and they will last.
http://www.batterychargers.com/battery-chargers/

 

Yes, but a decent charger you can get off Amazon for about $80.. does all of that deep charging and trickle charging..