[TenTec] DC Power Supply Backup

[Dr. Gerald N. Johnson, electrical engineer]

Its more likely that the crowbar would fry than the battery. A good
battery can deliver a couple kiloamps short circuit current and the
crowbar SCR probably will melt at that current. Then the battery will be
run dead if the wires between the power supply and the battery don't
melt the solder from the lugs.

The supply to the battery and the loads placed on the battery both need
to be protected by fuses or circuit breakers because of that short
circuit capability of the battery.

Sealed or gel cells do have limits on charging current and sometimes
load current. Exceeding those limits will shorten the battery life,
sometimes drastically.

73, Jerry, K0CQ

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Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.