Electrical Query on 48 Panhead

[harleygreg]

Hi Guys

Is the wiring loom (recently replaced) capable of handling; short term use of all spotlights (2 at 35w), headlight (35w), tail light (5w), brake light (15w) etc etc, with a 6 volt battery (22ah)? This would be drawing 125w with 6 volts and so 20+ amps? Should I be using LED bulbs?

I have installed an 8-0-8 amp ammeter (which is obviously too small). I can increase the range by using a shunt resistor but can't remember how to calculate the correct shunt resistance - any electrical engineers around? Would it be 0.05 ohm and 150watt??

Thanks

Greg

[duffeycycles]

They had all of that + fender light,sidecar light & taillight without ever knowing what an LED bulb is

[aumick10]

Greg,
A 0.5 ohm 72 W shunt resistor would give you a 20 a range on your ammeter.
However I think the 20 amps would be too much for your wiring.

I would expect the spotlights are wired through a relay and powered directly through a fused supply from the battery.

I am sure this has been done before and someone with experience will hopefully confirm this.

Cheers,
Mick

[tfburke3]

The ammeter shows the difference between the load and generator output,so you may be ok.
Tom

[aumick10]

Tom,
Until the motor stops with everything turned on.

[jorrow]

Not sure on a 48 but on my 47 the headlights and spotlights were either-or, not both simultaneously.

[tfburke3]

Yeah ,theres that.The other worst case is charging a dead battery.
British car friends who want to keep thier original Lucas 30A gauges with an alternator conversion shunt the ammeter with a piece of 14 gauge wire.Readings are about halved ,but the numbers arent considered as important as which side of the 0 the needle is on and keeping the original gauge.
Tom

[Rubone]

H-D always wired spotlights to low beam side of a 21/35W bulb. They were intended as passing lights, not running lights so draw was intermittent. So was brake light. The battery covers the momentary drop, continuous use will drain the system. The fender light and taillight also functioned as parking lamps in those states where they were required, but leaving them on longer than a short period is a dead battery.

[harleygreg]

thanks guys, terrific!