At 06:01 PM 12/9/2008, M'obeechi wrote: >starting battery. Since this is DC, is that going to make a terrible >difference? Will I need to use heavier gauge wire? I suppose I could >wire in two 4 gauge wires between the engine and the starting battery. Ten feet of #4 at 100 amps will drop a quarter-volt and dissipate 25 watts (85 BTU/hr). Change any of the values and the rest change proportionately, e.g. if your starter in the dead of winter draws 400 amps, you'll drop a whole volt across ten feet of #4 and dissipate 100 watts of heat in the wire. According to Bosch, you shouldn't drop more than half a volt in the starter supply cable *with the starter shorted* (that's what they say, but I wonder if they really mean locked-rotor rather than a direct short...) According to DIN standards, #4 could carry 100 amps continuous at 30C/80F, but you would need #2 to carry 100 amps at 50C/120F. http://www.stealth316.com/2-wire-resistance.htm has a calculator that lets you specify length and current to calculate voltage drop for various AWG or DIN gauges.
-- David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage," '85 GL "Poor Relation" ------------------------------------------------------------ + To unsubscribe from the Vanagon List send an e-mail to + listserv@gerry.vanagon.com with SIGNOFF VANAGON + in the body of the message. ------------------------------------------------------------ |
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