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PriUPS Bonus: Multiple Supply Examples - The SMALL
Here are details of the "small" system, using a non-rack-mount UPS and a
single 24V switcher. As of the moment, I have not found a suitable UPS on
eBay meeting my criteria. I got what I thought was a perfect one, i.e.,
for almost free, but when I tried to use it I found it didn't have "cold start,"
which is critical. More info as it becomes available...
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Small System |
Power Available |
~800W at 115VAC |
Power source |
Prius HV system - no power from 12V |
Converters used |
One Unipower 24V 50A switcher (RMP24/50) |
Voltage supplied to UPS |
28VDC - runs UPS and charges UPS batteries |
DC from Prius HV |
210-230VDC, 6Amps |
UPS model |
APC Back-UPS Pro 1400 |
System Weight w/o Batteries |
23lbs UPS, 9lbs switcher = 32lbs |
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I was able to pick up an APC 1400kVA UPS on eBay for the usual song.
It was offered without batteries, which partly accounted for the very
low price, but was complete with the Anderson connectors and the parts
that make up the battery pack. I realized after a quick look that
this one would be almost trivial to modify. |
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The yellow connector in the rear, as supplied, simply interrupts the
ground conductor from the battery pack, rendering the UPS inoperable.
The UPS is activated by shorting the battery ground to the unit ground
with the yellow jumper plug. |
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Here is a side view of the original wiring, with the two black
ground conductors going to the yellow connector block. My goal was to
provide 24 volts from an external supply directly to the UPS. |
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1: Remove the yellow connector from the chassis and pop the
connector pin on the black wire going to the UPS circuitry. 2:
Remove the connector pin on the black wire in the battery compartment
connector (top photo) and put it aside.
3: Connect the black wire removed in step 1 to the battery
compartment connector.
4: Mount the battery compartment connector (grey) where the
yellow connector was removed. |
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Performing the 4 steps listed above leaves the unit with the 24V
input to the UPS circuitry on the rear panel connector. The parts in
front of the reassembled UPS are left over. The two yellow
Anderson connectors are unused. The fuse link (blue cube) that
would normally protect against overcurrent from the battery is
unnecessary because the 24V power supply is current limited. |
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Total weight of the slightly modified UPS and the 24V power supply
is under 32 pounds.
With a bit more work and a bit more weight one could rewire this
system so that the batteries remained in the UPS and would be charged
when the 24V supply was running. This would allow it to provide
power with the Prius turned off. Since I received no batteries
with the unit, I did it the easy way. |
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