Re: Batteries in Power Supply

The whole point is to look at it as a concept and see if it makes
sense. If the idea has merit, then the details are worked out.

I mentioned in my previous post the battery would connect to the
supply via a diode. This is to keep the supply from charging the
battery when its contribution is not required, i.e. like 96% of the
time.

It does not replace the filter capacitor, it's just that it doesn't
have to be as large, the same way the transformer can now be 5 times
smaller.

The details would be designing a trickle charger for the battery,
which by the way would have to be NiMH to avoid memory effects . The
other detail would be how to remove the battery from the circuit when
power needs to be off. Etc, etc.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Kevin P. Martin"
<kpmartin@t...> wrote:

> 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@c...>
> [mailto:bwjarandall@c...]
> 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.