DC power supplies rarely care if there is another source of voltage that
the power supply sees on it's input. It is not unusual for a AC/DC
supply to have to power up into an existing potential. Many DC loads,
on a brief power interruption, still have significant voltage that the
power supply is going to see when AC returns.
* This comment is general and may not apply to every power supply *
From experience the only supply I know that won't deal with power on
the output is one of the larger MeanWell AC/DC 48V supplies. The
internal voltage regulator is too slow to respond and ramps the voltage
up over the high voltage limit and shuts the power supply down if it's
powered up when there is already a battery voltage on the output. If
you power up the supply and then add the battery it's fine - but not
very practical.
Every other AC/DC supply I have tried has worked fine doing what you are
asking to do.
Mark
On 4/24/15 1:34 AM, TJ Trout wrote:
I have a dc load that I need to power using a switching ac to dc power
supply but I also occasionally need to power the load from batteries,
I was planning to put the load, power supply and battery clamps in
parallel, is that a acceptable solution ? Can I power the load from
battery and back feed DC into the supply without damaging it? Would
there be a significant drain back into the supply?
If this isn't ok, what's better solution? Diode ? SPDT switch ?
The load is 50V 100A so that makes diodes and switches a challenge to
find. ..
