On 9/27/2013 11:38 AM, sms wrote:

If we got 90AH batteries they would actually be about 50AH at the
discharge rate we're doing. So that'd be about 600WH so we could do 300
watts (4 lamps) for two hours.

We'd run one cable for every two lamps, so 12.5 amps per cable.
CY: Yes, that's workable.

Two lamps would be on each tower, and each battery would power two
towers. However we might decide to use smaller batteries and have one
per tower.
CY: Also workable.


We need to be able bring them out to the practice field as well, which
is a long way from the band room, so we'd need to put them into one of
our golf carts (one battery powered one gasoline powered).
CY: Or back of someone's pickup truck?


We'd like to avoid gasoline or diesel powered generators. Batteries we
can charge for "free."
CY: Please research charging of trolling batteries. IIRC, takes a
different charger, different than vehicle starting batteries. And if the
detail minded adult doesn't hook up the charger every night after
practice, the second night, the battery goes below 50% charge, and
damages the battery. Seems risky, to me.


The school district is too cheap to pay for permanent lights.

They can't practice in the daytime.
CY: Budgets are tough every where.


We also have the option of buying some generators and getting AC powered
lights. This may be a better option just because there is no need to
have someone maintaining all the batteries.
CY: Sounds like you're already using generator and 120 VAC lights, but
they are rented. Sounds like you're trying to decide if you want to buy
and maintain your own equipment. I think in the long run, the "own the
equipment" can be cheaper.