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SLA Charging

817 views 3 replies 4 participants last post by  brianb00 
#1 ·
Bit of a noob when it comes to this electrical stuff :)

So just bought a used nite hawk Avenger light that uses a small SLA Battery (2.6ah I think). The Charger was missing and looking around locally I have only found a 1000mA charger which may be too much for this small battery.

I was wondering If I can use the charger for my 12v drill to at least test the battery to see if it will hold a charge. The charger I have has an output of 15vdc, 500ma for a 12v nicd battery.

is this something that will work or do I need to keep looking for a SLA specific charger.
 
#2 ·
With both chargers you will probably destroy the lead acid battery. The chargingprocess of a Lead acid battery is completely different compared to charging of a nickel battery.
The biggest chance on succes you have with the 15V, 500 mA charger. But when it works it will be a matter of time before the battery is dead.
 
#3 ·
SLA's are pretty forgiving, they will usually accommodate a NiMH or Ni-Cad charging schedule without any issues. Most deep cycle SLA's can be charged at 1C, so your 1000mA charger should be fine. The important thing is to make sure your charger is for the right voltage.

(I should point out that this is true for dV/dt chargers, but not for those that monitor temperature)

If the charger is not "smart" (does not automatically switch to trickle mode) then you will need to manually unplug the battery when it is charged - which is at best a guess.
 
#4 ·
SLA can be charged with the 12v 1000ma

Is th 1000ma charge a battery charger that has a fixed current ? Or is it just a 13.8 power supply capable of 1 amp ?

If it is the later you can trickle charge safely doing thefollowing:

Put a series resistor of 15 ohms, this will limit the charge current to 10% of max AH, assuming the discharged battery is sitting near 11 volts. As it ramps toward 13.8 the current will drop. Probably around 8 hours into the charge cycle you will be over 50% charged. Check the voltage of the battery, stop charging if it is above 13. This will at least let you know if the battery will take a charge and you wont damage it with over current.

If you have a 1000 ma constant current charger you can do something similar with a resistor and a zener diode in parallel with the battery. If you have questions about this drop a note.

bb
 
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