Hello.
I use some AC tools with universal motors powering them with 120VDC supply. But have not tried feeding a tool battery charger with that voltage. From the charger schematic attached section, should I safely try ?
So the charger would be ac/dc input ? BD1 would be only a power steering, not a 'rectifier' and insensitive to any input polarity connection. Already tried with plain LED bulbs and they work happy. But are not stamped/rated for 120V AC/DC
When fed by 120VAC, LED bulbs circuitry is supplied by ~165VDC at the bridge output. When fed by 120VDC, LED bulbs circuitry is supplied by ~119VDC at the bridge output. Right ?

 

A few things to watch out for:
1. Is the bridge rated for double the current? Because power dissipation is no longer shared over four diodes.
2. Does R7/R8 provide enough current at 120V DC for it to start up?
3. Can it still provide maximum output? (which occurs at the end of the bulk charge (constant current) phase, and the beginning of the constant voltage phase)?
4. Does it get too hot? From lower voltage supply it will need more current, so it will run a little warmer.

I don't see any harm in trying it.

 

The charger might use a transformer to provide both isolation and voltage reduction. In that case, DC power is not so simple. A visual inspection can verify if there is a transformer.