USB outlets hooked up to the battery...warning


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New to the NC700 here, just bought a 2013 model with 8000 miles on it, from a fellow forum member. Bike was in great shape, bought it, hauled it home, and , because I like to know what I am starting with, I did some work on it- cleaned the chain ( needed it), flushed the brake fluid, inspected it, etc. I also put it on my Battery Minder, which is a trickle charger. It charges the battery up, then flashes it's little green LED to tell you it is all the way charged. I let it go for a few hours, and although the red charging light was on, the battery never came to a full charge. I removed the maintenance cover, and checked voltage of the battery...( it had been off the charger overnight) 12.2 volts.

This got me to thinking...I had noticed that the clock had reset to 1 AM when I took it for a test ride, but just figured the PO had never set the clock. I doubted that it was the battery, since the PO showed me a receipt for a replacement battery, AND for a replacement of THAT battery, when it died an early death. It all started to make sense- I found a USB adaptor wired directly to the battery. Maybe everyone here knows that USB adaptors have a parasitic drain, ( I did), but the PO did not know. I realize it is tempting to hook it up hot, so phones, etc, can be charged while not riding, but even at 30-40mA, which is the drain of one of these units, a battery can be drained in a few days. Deep discharging of a battery WILL eventually kill it.

I did take the battery out, and give it a full slow charge, and it appears to be holding at 12.48 volts, which means it might be okay, will be checking it later today.

Hope this helps someone.


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That’s a good reminder about the parasitic drains from USB converters/adapters. While at times it’s useful to have the USB outlet powered on when the engine is off, I either put the fixed USB jack on a separate switch, or use a USB adapter that plugs into a 12 volt outlet. With the plug in type, you can pull the USB adapter out when it’s not in use, to prevent drain.

Depending on temperatures, and which open circuit voltage vs state of charge chart you view, 12.48 volts equates to roughly 75% battery capacity. Perhaps the battery has suffered some permanent damage from the deep discharge, or it just hasn’t been fully restored yet.


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I also learned this the hard way. I use a Centech box to power my accessories. It is controlled by the ignition switch.


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I put this one on to give me two USB ports AND it has an on/off switch to stop the battery drain:


Also uses SAE quick disconnect that my battery tender uses.


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I learned how here on this board...

the USB comes off the battery right over a fuse then to a "switch" that makes sure the USB ports are OFF when the key is off.

Switch connected to the wire that makes the front turn signal always on. (and no, it doesn't turn the power off and on when I use the signals! Tested for that first.)

I also put a volt meter on a line off the battery so that I can watch it change as I turn things on and off.


Annnd thats why we use a switched power source, preferably controlled at the bikes key for accessories so you dont forget to use the separate switch.

Great for you to mention it though, as the first thing most people think of is the battery is an easy spot to get power, without realizing consequences.


Good info, I prefer mechanical vs electrical work. I'm borderline electrical illiterate. LOL

My bike had a cluster installed in the frunk with a 12v outlet and 2 usb outlets by previous owner. It wired correctly, as it is wired to the ignition switch. I have only used it a couple times, but went to use it while on a trip a month or so ago and it wouldn't work, then noticed the blue power light on it was off. So I'm assuming blown fuse somewhere.