12v Lead Acid Charger Ideas?

[fogus]

Hello All (brand new here),

I am looking for suggestions on charger options for lead acid batteries. I have a pair of "Thorex" 10 million candlepower cordless spotlight, which run on 12v lead acid "security" batteries (7.5Ah).

My problem is that the batteries seem to die a nasty death if left in the charger, but also run down (and thereby die a slow death) if left unplugged for several months.

Does anyone have suggestions on building a better charger? Specificly, I would be interested in knowing:
What voltage should I charge at?
How should I have the circuit decide when to stop charging?

Thanks,
~fogus

 

[lightforce2]

I use the Battery Fighter Junior for a 7amp and a 3amp 12v SLA,
an excellent charger

http://www.batterydoctor.ashop.com.au/p/73672/12v-junior-battery-fighter.html

cheers

 

[fogus]

Hey, thanks for that.

Also, thanks to the mods for previewing my post so quickly. Very impressive.

 

[Mr Happy]

Lots of information here: http://www.batteryuniversity.com/partone-13.htm

You may imagine from the complexity of that information that cheap battery chargers are not likely to do a good job and the batteries will have their life shortened as a result.

The one mentioned by lightforce2 sounds like it applies the more sophisticated charging algorithms that are needed for long life.

 

[fogus]

Lots of information here: http://www.batteryuniversity.com/partone-13.htm

You may imagine from the complexity of that information that cheap battery chargers are not likely to do a good job and the batteries will have their life shortened as a result.

The one mentioned by lightforce2 sounds like it applies the more sophisticated charging algorithms that are needed for long life.

That's exactly what I was thinking: the constant charge output from my simple charger (just a transformer) was doing a bad job. On the other hand, the chargers for my BPR-40 radios is complex (it gives notification of charging, 90%+ charging, and charge maintenance charging) and works extremely well.

 

[glockboy]

I used this one.

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200332201_200332201