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shorting the usb pins while battery is installed


turbocad6
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ok I have a question about the dna60 in particular but since there is no dna60 section here yet I figured I'd just ask it here in the dna75 section :)

I'm building a dna60 mod that uses a docking port to charge through a charging dock, and the docking port is directly connected to the usb input connector. 

my question is, what would/should happen if the pins on this port were inadvertantly shorted while in a pocket, I'm trying to determine how recessed and protected this docking port should be. I've considered using a docking port in the past to directly connect to a lipo for fast charging but decided against it for safety reasons, but here the battery is somewhat isolated from a direct connection to a certain extent, just not sure to what extent and I'm trying to avoid any destructive testing at this point :)  

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Well do you have a multimeter? If it has zero volts there then shorting the docking port by keys, coins, etc. isn't going to do anything. I find most USB connections are usually dead on the receiving end for the power connections. But it won't be dead if you plug in the USB cable to power though.

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BillW50 said:

Well do you have a multimeter? If it has zero volts there then shorting the docking port by keys, coins, etc. isn't going to do anything. I find most USB connections are usually dead on the receiving end for the power connections. But it won't be dead if you plug in the USB cable to power though.



Bill,

I was going to stay out of this because if the OP does something wrong guess who will be blamed.

Anyway, I agree with you and if there was any current available I am sure someone would have blown up a cellphone by now.

That said I would short the power pins in the USB with a 1k ohm resistor and then measure the voltage across the resistor.

Just using a DMM (digital multi-meter) that typically has an impedance of at least 10 meg ohms you may measure a voltage that is nothing to be concerned about because there is no current of consequence behind it.

Using the 1k resistor will eliminate any high impedance voltage that the meter may be able, without the 1k resistor, to read.

Using the 1k resistor and a DMM should be more than adequate to determine if the power pins are hot or safe around keys, change and whatever else you may have in your pocket.


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HolmanGT said:



Bill,

I was going to stay out of this because if the OP does something wrong guess who will be blamed.

Anyway, I agree with you and if there was any current available I am sure someone would have blown up a cellphone by now.

That said I would short the power pins in the USB with a 1k ohm resistor and then measure the voltage across the resistor.

Just using a DMM (digital multi-meter) that typically has an impedance of at least 10 meg ohms you may measure a voltage that is nothing to be concerned about because there is no current of consequence behind it.

Using the 1k resistor will eliminate any high impedance voltage that the meter may be able, without the 1k resistor, to read.

Using the 1k resistor and a DMM should be more than adequate to determine if the power pins are hot or safe around keys, change and whatever else you may have in your pocket.


I totally agree with you and VapingBad. :)
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