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what voltage to fully charge a leand acide battery ?

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Thunderchild

New Member
What voltage do i need to apply to a lead acid battery to fully charge it ? will it still fully charge at 13.5 volts albeit more slowly ?
 

k7elp60

Active Member
For a 12V the normal standby or float charge is 13.5 to 13.8 volts.
 

Hero999

Banned
For the camping trip, of course.:D

It depends on how quickly you need to charge it.

It can be left to float at 13.8V forever but it will take ages to charge at that voltage.

If you want to charge it quickly charge at a high constant current (>50A or so) and stop charging when the voltage reaches 14.5V.
 

Thunderchild

New Member
yes for the Rotaract district 1070 camping weekend.... gotta power that fridge with something for 24 hours... plus the music, are you missing not comming now ?

I'll get it down and put it on charge...
 

MikeMl

Well-Known Member
Most Helpful Member
I'll get it down and put it on charge...
How long since it was last charged/floated? If it has been sitting idle for several months, chances are that when combined with ~50ft of rope, it will make a great accessory for your boat. Idle flooded-cell batteries loose about 10% of their charge per month, especially in the summer. Sealed-Lead-Acid (SLA) batteries loose about 3-5% per month.

When idle, flooded-cell lead-acid batteries should be recharged (to make up for self-discharge) at least every two weeks, more in hot climates. SLA batteries should be recharged at least once per month.

I keep all my little-used batteries on continuous float-charge: 12.9 to 13.2V for flooded-cell, and 13.4 to 13.6V for SLA.

For charging, 14.2-14.5V for flooded-cell, and 14.7-14.8V for SLA. Switch the charger to the float voltage when the charging current drops to < 0.25A (for a 50 to 125AH battery).
 
Last edited:

bountyhunter

Well-Known Member
I keep all my little-used batteries on continuous float-charge: 12.9 to 13.2V for flooded-cell,
+1

13 - 13.2V is about right on for a continuous charge on a "12V" wet cell lead acid. For fast charge, 14V is OK as long as it is not left on it indefinitely.

BTW: the battery makers publish recommended voltages for rapid charge and float charge for their batteries.
 

Boncuk

New Member
If you want to charge it quickly charge at a high constant current (>50A or so) and stop charging when the voltage reaches 14.5V.
14.5V charge voltage is already in the deep red zone.

Wet batteries can safely be charged to 2.4V per cell (total 14.4V).

Any higher voltage initiates gasing (hydrogen + oxygen = devastating if touched off :mad:) of the battery, which might become a risk in unventilated rooms.

Boncuk
 
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