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re: battery interconnect size
25 apr 2000
dlehmicke wrote:
>i must have missed something here. i've heard 100 a currents and 12 gauge
>wire in the same sentence. that makes my teeth hurt. what did i miss?
hey, why not? this isn't house wiring: (4kw+10%)/48v/2strings = 46 amps
per 48v string, max (vs 235 a fusing current for 12 ga wire) with a 4 kw
90%-efficient inverter load. a 1' 0.001588 ohm jumper loses 3 watts at
46 a, with tolerable and maybe desirable heating, and that's only 1% of
a typical day's energy collection, say 3 w x 10 links x 2h = 60 wh per
8kwh, if we use the 8 kwh over 2 hours. using 8 kwh over 8 hours lowers
i to 12 amps, so the links only use about 0.2 watts each, ie 16.7 wh,
0.2% of the daily total collected energy.
softer links in the strings can provide desirable internal fusing, with
individual equalizing cross links to keep batteries charged equally and
allow the working units in a string containing a high resistance battery
to continue to contribute to the system capacity. we might add individual
current transformers to monitor battery health and flag bad batteries,
so they can be disconnected if leaky and later replaced.
nick
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