Re: microcontroller circuit help


ehsjr wrote:
mookiewookie@xxxxxxxxxxx wrote:
Ed, could this setup be used with a NiMH battary pack and a smart
charger or is it for acid batteries only.


In the future, please bottom post, below the post
to which you are replying.

No, the setup in the previous posts won't work for
a NiMh pack with a smartcharger. The setup diagrammed
below will do that.

D2
+------------------->|--------------------+
| a |
| Ry1-1 D3 |
+-----+----+---o o------o--->|---+-----+----+
| | | | | | a | | |
| | | | | | | | |
+| [D1] [Ry1] |> |<-' | <| Ry2-1 | [Ry2] [D4]
----- |a | | | | | |a
|Power| +----+ o o------+ | +----+
|Supp.| | | | +| | |
|12 V | | | [NiMh] ---- / ---
----- | [LOAD] | |Smrt| \<--[1K]--/ \TL431
-| | | v--o |Chgr| / ---
| | | ---o ---- \ 50K |
| | | Ry2-2| -| | |
| | | | | | |
+-----+-----------+------+------+----+----------+


When AC is available, Ry1 is energized and the load
is connected to the power supply and disconnected
from the load. Meanwhile, the smartcharger charges
the NiMh pack. D2 isolates the power supply from
the NiMh and smart charger, and allows Ry2 to be
energized by the power supply when AC is available.

When AC power is off, Ry1 de-energizes, and the load
is disconnected from the supply and connected to the
Ry2 contact. Ry2 remains energized by the battery through
Ry2-1 and D3 until it discharges to the voltage you set
by the 50K pot, so the load is connected to the battery
through that relay contact and the closed Ry1-1 contact.
D3 also isolates the NiMh and charger from the power
supply while AC power is on.

Once the battery reaches the voltage you set, Ry2 drops,
disconnecting the battery from everything but the smart
charger. (The smart charger should have built in
protection to prevent the battery from discharging into
it. If it does not, use the Ry2-2 contacts in series
with the pack as drawn.) Ry2 will stay de-energized
until AC power is restored.

D1 and D4 are there to conduct the spikes created when
the relays de-energize.

Set the 50K pot so that Ry2 de-energizes when the pack
discharges to 10 volts - or to whatever the manufacturer's
recommendation is per cell x 10, if you know it.

Ed

Ed, can you explain the relay wiring in some detail. I`ve never worked
with relays before and so am not really sure how to connect them. The
dpdt relay has six leads, and looking at it from the bottom, i assume
lead 1 and 16 carry the electromagent, 4 and 13 are poles, 6 and 11 are
NC and 8 and 9 are NO in this config:
1--------4-----6-----8
16-----13---11-----9
For lead-acid circuit, am I to connect D8 to lead 1 but then what about
the other leads. Again your input will realy help.

.

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