At 09:58 PM 6/7/2005, Jamey Wright wrote:
>Good info. I've been contemplating batteries here lately as well. I run a
>Mastr II 30 AMP PS for the repeater. But if I were running a smaller, lower
>powered repeater than the MASTR II, and using an Astron 35 or 50 amp PS for
>power supply and floating the batteries, what would keep the PS from melting
>down if the AC power was off for an extended period of time and the
>batteries were discharged then AC power restored?
The power supply's current limiting.
> I was charging a small motorcycle type battery with my 35 Amp
> Astron and melted the insulation off
>of the 12 ga wire from the PS to the battery as well as killed the supply.
12 ga at 35A?
You have to figure that the power supply will need to sustain the
discharged batteries for a few minutes.
No idea why the supply failed, unless it was the crowbar issue
mentioned before, and it actually happened when the lights went out,
or maybe just as they came back on.
A crowbar on a supply that's connected to a large battery, is pretty
silly, since the battery can absorb any excess energy in a spike.
If the supply goes nuts, that's another issue, and best dealt with
separately, but the crowbar wouldn't trip until you had dumped a TON
of excess energy into the batteries anyway.
I size my wire to twice what is recommended for the fuse current, at minimum.
My home system runs #4 to the distribution block.
The "aw shit" fuse located right off the battery terminal in this
system is 40A.
I definitely want the fuse to blow, not the wire.
The individual loads have 5A or 10A fuses as appropriate.
This for some 50W transcievers and an IRLP computer, and plasma
screen terminal.
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