Switching power supplys or chargers ? - Electronic Circuits Projects Diagrams Free

wkyong · 1st May 2008, 01:41 PM

Can 2 same switching power supplys or chargers (o/p=12Vdc) be connected in series in order to charge a 24Vdc battery?Is blocking diode necessary??
If yes where to place it?

mneary · 1st May 2008, 11:15 PM

If they have the (-12) connected to the earth line, the answer would be no. Also, you need more than 24V (more like 27-28V) to charge a 24V lead-acid battery.

Blocking diode won't help.

wkyong · 2nd May 2008, 01:04 AM

Quote:

Originally Posted by mneary

If they have the (-12) connected to the earth line, the answer would be no. Also, you need more than 24V (more like 27-28V) to charge a 24V lead-acid battery.

Blocking diode won't help.

Actually I want to ask whether 2 same SMPs can be connected in series or not? Thanks!

Conradb · 3rd May 2008, 06:27 PM

I believe that the correct answer is yes and no. Yes if you are not worried about stability and lots of smoke :-), but NO if the load is capacitive or variable, since the sense feedback circuits in the regulators will fight each other and oscillate since they do not have a real reference, and are using each other as voltage dividers. (you will need to create one, which will waste power!!!) Not practical.

I would not even try connect a small load to series connected SMPS, for this case, one or both would be destroyed by the Battery.

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1st May 2008, 01:41 PM	(permalink)
wkyong	Switching power supplys or chargers ? Can 2 same switching power supplys or chargers (o/p=12Vdc) be connected in series in order to charge a 24Vdc battery?Is blocking diode necessary?? If yes where to place it?

1st May 2008, 11:15 PM	(permalink)
mneary	If they have the (-12) connected to the earth line, the answer would be no. Also, you need more than 24V (more like 27-28V) to charge a 24V lead-acid battery. Blocking diode won't help.

3rd May 2008, 06:27 PM	(permalink)
Conradb	I believe that the correct answer is yes and no. Yes if you are not worried about stability and lots of smoke :-), but NO if the load is capacitive or variable, since the sense feedback circuits in the regulators will fight each other and oscillate since they do not have a real reference, and are using each other as voltage dividers. (you will need to create one, which will waste power!!!) Not practical. I would not even try connect a small load to series connected SMPS, for this case, one or both would be destroyed by the Battery.