RE: [CAD_CAM_EDM_DRO] Re: Batteries in Power Supply

I think UPS's use power supplies that monitor the cell voltage, which are more
complex than just a transformer and rectifier.
They have to be able to generate controlled voltage and current despite line
voltage changes, and shut off the charging current when the battery appears
charged.

You can calculate how much gas would be evolved if the battery were
fully-charged and all the current went into generating gas.
96500 coulombs (amp-seconds) of charging generates 1/2 mole of hydrogen and 1/4
mole of oxygen gas molecules (about 11 and 5.5 litres volume respectively) and
consumes 18 grams (about 1/2 ounce) of water *per cell*.

Now, if your input supply only generates 10 amps, it takes 9650 seconds (about
2.7 hours) to pump 96500 coloumbs into the battery, so a fan should be able to
dissipate it from your cabinet, but you should also make sure the gas cannot
accumulate in the room over a longer period (most houses are pretty leaky, but
basement air can be stagnant).

Your main concern would be making sure you keep the cells topped up with fresh
distilled water to replace what is electrolysed away.
-Kevin Martin


-----Original Message-----
From: Bernard R <bwjarandall@...>
[mailto:bwjarandall@...]
What do the UPS people do? The ones I have taken apart all used
sealed Lead-Acid. I'm presuming that the batteries would only be
charged when the CNC is on so it should be a reasonable
charge/discharge cycle. With this type of supply I would be using
forced cooling which should dissipate any gases.