Charger circuit for 6v sealed batteries

[Norm Dresner]

I've got a bunch of 6v (?lead acid) sealed batteries salvaged from some
failed UPSs. The batteries are fine but I have no way to recharge them once
I use the current charge. Does anyone have a URL for an on-line circuit or
App Note for a charger that will automatically shut off when the battery is
charged?

Norm

 

[Norm Dresner]

I've got a bunch of 6v (?lead acid) sealed batteries salvaged from some
failed UPSs. The batteries are fine but I have no way to recharge them once
I use the current charge. Does anyone have a URL for an on-line circuit or
App Note for a charger that will automatically shut off when the battery is
charged?

After posting the above, I was scanning for something entirely different and
came across this circuit which looks quite adaptable.

http://www.elecdesign.com/Articles/ArticleID/1823/1823.html

Norm

 

[budgie]

I've got a bunch of 6v (?lead acid) sealed batteries salvaged from some
failed UPSs. The batteries are fine but I have no way to recharge them once
I use the current charge. Does anyone have a URL for an on-line circuit or
App Note for a charger that will automatically shut off when the battery is
charged?

I'd recommend the UC3906 from Unitrode/TI. The AppNote hides out there on the
web as SLUA115.pdf and contains much useful care_and_feeding information.

 

[Pooh Bear]

I've got a bunch of 6v (?lead acid) sealed batteries salvaged from some
failed UPSs. The batteries are fine but I have no way to recharge them once
I use the current charge. Does anyone have a URL for an on-line circuit or
App Note for a charger that will automatically shut off when the battery is
charged?

The likes of Yuasa have very helpful info.

Lead-acid charging is typically constant voltage as opposed to constant current
for Nicads and Ni-Mh etc.

http://www.yuasa-battery.co.uk/Redbook5.html


Graham

 

[Michael]

I've got a bunch of 6v (?lead acid) sealed batteries salvaged from some
failed UPSs. The batteries are fine but I have no way to recharge them once
I use the current charge. Does anyone have a URL for an on-line circuit or
App Note for a charger that will automatically shut off when the battery is
charged?

Norm

If your batteries are lead-acid, you cold use an automotive battery
charger.

Back in 1976 or so I fell heir to several 6-packs of Gates 2v 5AH
cells. From that time to the present I have charged them with the car
battery charger I built (from a circiut in a Motorola SCR data manual).
To date, only about half the 2v cells have gone bad, had to be tossed
out. Some of the remaining cells form a UPS for a temperature data
logger I built.

 

[budgie]

If your batteries are lead-acid, you cold use an automotive battery
charger.

Many many automotive battery chargers lack the regulation required to properly
charge a SLA.

Back in 1976 or so I fell heir to several 6-packs of Gates 2v 5AH
cells. From that time to the present I have charged them with the car
battery charger I built (from a circiut in a Motorola SCR data manual).
To date, only about half the 2v cells have gone bad, had to be tossed
out. Some of the remaining cells form a UPS for a temperature data
logger I built.

These Gates (Cyclon) cells have an interesting characteristic, in that the
published data states that they can be connected directly to a low impedance
voltage source at the float voltage regardless of state-of-charge, and will
withstand the sometimes huge inrush current. The average prismatic SLA won't
handle that at all.

Too high a float voltage will kill the Gates/Cyclon cells in short order. We
have a communications test set (by a well-known US maker) where the charge
circuitry is a total crock, as are the float voltage setting intructions in the
maintenance manual. These would regularly kill a set of those same Gates/Cyclon
2v %.0Ah X cells.

 

[Gary Lecomte]

Check out my charger at:
http://www3.telus.net/chemelec/Projects/Projects.htm

Its Simple and works very well.

Gary