Voltage will be only as much as the battery can provide..in other words 14.4 volts at the most. Most of the electronic charger packs can handle 8-20 volts DC. There IS a bunch of current flowing to the starter as it spins the engine, but it doesn't effect circuits in line with it. Otherwise, you'd blow all your home electronics up when your AC unit kicked on or the microwave was used. The reason most power is cut off when starting is that the OEM wants all non-necessary components off so all available power goes to starting the engine.

 

56tbird, It's the collapsing magnetic fields in the starter coils that create the back emf which can wreak havoc with in-line electronics. This is why even small relays attached to transistorized electronics have a diode across the relay coil. This is in order to suppress the momentary stored energy in the coils magnetic field.
Here's another example...http://www.mrdistribution.co.uk/pdf/diode.pdf

 

2010 Ultra. I have been using the lighter socket for Garmin, Ipod, cell phone and anything else needed. So far no problems. Its a good idea to check clearance as some plugs can stick out too far and contact the tank in a hard left turn.

 

One of these will solve that problem ! Rocketfish USB adapter charger it is almost flush when you plug into Cig. lighter

 

That is very interesting and the first plausible explanation of a possible problem it could cause beyond Harley just covering their butts. I use mine to power my GPS but I have to turn it on - it does not just turn on with power. So it seems that would not cause a potential problem. Right?

 

Potato Potato, Most (but not all) of todays electronics contain what's called a protection diode. This diode protects the electronics from momentary reverse polarity connections, like if you touch a 9 volt battery backwards to it's battery clip. This same diode will somewhat protect your electronics from reverse voltage transients. The problem comes in where the voltage rating of diode is exceeded by a voltage higher than the diodes rating, also known as 'peak inverse voltage' or PIV for short. This can destroy the diode over time and cause a permanent short circuit, or pass the voltage spikes on to the more voltage sensitive circuitry and destroy them. Where do these high voltages come from? Well, anytime you have an inductor or coil of wire like the kind found in electric motors, starters, relay coils, etc. and you apply a voltage across it, it will create a magnetic field and hold a momentary charge. As the voltage is removed from the coil that field collapses and creates a backwards flowing high voltage spike.
Now when a starter is spinning you can imagine the three or more coils within the starter sequentially charging and discharging at whatever rate the starter is spinning. This is creating a lot of 'back emf' that is normally absorbed by the battery, as the battery acts like a large capacitor. However, equipment that is wired directly to the battery and consequently to the starter will also take this high voltage hit, especially on a failing battery. This 'coil and capacitor' combination is the same principle used to generate high voltages in magnetos, electronic ignitions, tasers, Tesla coils etc. It just happens to be an unintended consequence when applied to automotive starters, relays, etc. If you hook up an oscilloscope to any automotive starter you can clearly see the high voltage spikes lasting microseconds, too fast to be read by normal digital or analog voltmeters however.
So to answer your question, If your GPS or other electronics has a simple protection diode built into its circuitry and it's somehow wired directly to the battery while the starter is cranking, you should have a modicum of protection.

 

You are way too smart. Reading your posts could cause brain damage to the rest of us. Are you an electrical engineer, or are you just smart about everything? Scary thing is, you explained it so well, I actually understood it!

 

I just have a dual lighter socket on a wire that plugs into the accessory wire that hangs out under the seat. I just run the wire back to my left saddle bag.

I have a USB adapter for my cell phone, and I have a 75w inverter for 110 volts and I charge up my laptop thats in my tourpack. I use them both at the same time.

I also use the 110 volt inverter to charge my extra camera batteries with a regular wall plug charger.

I've even left them charging with engine off for a an hour or two at a time when I've stopped for lunch and it didn't seem to kill the battery a bit.


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Well if we can use it for electronics, who needs the $500 Harley XM module? Just get the snap XM thing shown here
http://www.bestbuy.com/site/XM+-+Sna...&skuId=1166993

 

I use mine to power my GPS.