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Old 05-19-2009, 08:37 PM
bobjutsu bobjutsu is offline
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I don't know about H4's specific problems, but it is the amperage that burns shit out, not the voltage. Light bulbs, motors, basically anything that draws a set WATTAGE will draw excessive AMPERAGE if supplied with low VOLTAGE. Basically, if your battery and/or charging system is supplying low voltage, by design they will draw excessive amps in order to achieve the wattage required to perform it's function...which will cause things to burn out.

It's the same reason a bad ground causes bulbs to fry...voltage has to split between two loads, so low voltage is available to the bulb itself.

If you measure voltage from the ground side of the bulb, to your battery ground...that is your ground side voltage drop, and it should be zero (or damn close), otherwise you have a bad ground.

Last edited by bobjutsu; 05-19-2009 at 08:42 PM..
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