LABCO PS243 - Charging the battery

benitos wrote in news:db0655c6-cdee-4e28-93fa- snipped-for-privacy@googlegroups.com:

It will charge to maybe 30 percent, higher if the 12v supply gives a bit more then 12 volt.

Yes. A 12V lead acid battery is typically charged at 14.2 to 14.4 volts.

PlainBill

Le mercredi 5 septembre 2012 19:40:03 UTC-4, (inconnu) a =E9crit=A0:

wrote: >Hi , > >Having this power supply to provide 12V (with a back up bat= tery). > >The battery seems to be connected in // with the 12VDC output. > =

A 12V lead acid battery is typically charged at 14.2 to 14.4 volts. PlainBi= ll

Max I can go is 13.8V .

Is it OK ?

Also , because it's connected in // with the output , it's Ok if there is v= oltage across the battery all the time ?

wrote: >Hi , > >Having this power supply to provide 12V (with a back up battery). > >The battery seems to be connected in // with the 12VDC output. >

lead acid battery is typically charged at 14.2 to 14.4 volts. PlainBill

voltage across the battery all the time ? I missed the beginning of this thread, but if you want to float charge a 12 V lead acid battery, then 13.8 volts is the proper voltage to do so. The battery will maintain its charge without overcharging. If the battery is used and needs to be recharged, it will take longer, but it will work. Putting a 12 volt lead acid battery in parallel with a 13.8 power supply was a very common thing to do before all these fancy high tech battery control ICs became available.

Pat

But you better make sure the supply does not drag the battery down when power is removed.

I think I would at least have a resistor between them. There's guys around here that know a lot more than I about the care and feeding of batteries, but it is my belief that some resistance in series will help prevent overcharging. Perhaps as little as 10 ohms or so.

Mark Z.

or worse still, zap the output semis (that HAS happened to one PSU here).

No, you do not want any current to feed back into the unpowered supply. Use a good quality schottky diode of to appropriate current rating. Also, consider a fuse to avoid a fire. Lead acid batteries like to be charged from a constant voltage, current limited power supply.