USB and Cig sockets

Dave Jezza · Veteran Member

USB and Cig sockets

2weis · Senior Member

could be any number of reasons and only the previous owner will KNOW for sure why it is disconnected
my understanding is unless it is being use to power or charge something it wont draw power
all you can do is test the wiring to make sure there is no dead shorts and monitor it for current draw

brian

Dave Jezza · Veteran Member

Thanks Brian

Just did a bit of googling (shoulda done that first) and apparently they do draw a little charge when idle with nothing plugged in, so I'd guess that over time it could affect the battery.

I do use a small 1.5amp mini solar charger when parked up @ home.

rrobor · Veteran Member

USB is 5V so there will be a built in regulator. To get that to work you have to have an ambient current. What I found on line is its 500mA. That sort of current would drive a small torch battery. So yes if it was me, Id build a switch into that. I do think though that number is way too high, I wouldn't be surprised if there was a zero too many.

Tony Bev · Guru

I also think, so I could be wrong, that 500mA (half an Amp), is too high for a continuous current to a stand-by 5 volt USB port

It will be interesting to find out if anyone has actually measured the amps going to the stand-by USB port

I just have the normal female cigar connection, then use another male cigar connection with the USB slot on it

PeterD · Guru

Dave, do you have a digital multi-meter? If so could you use it to measure the current and report back to this thread.

Dave Jezza · Veteran Member

Just connected the empty socket wires to the battery and quite a bright little spark occurs when tapping the connectors onto the pole so there is obviously current draw when not in use. I think I'll just connect with small alligator clips when we need to use it.

PeterD can you tell me what setting to put the multi-meter on and where to connect it to get the reading please? I'm not real meter savvy.

PeterD · Guru

Dave, the big spark when you first connect up will be some smoothing capacitors in the regulator charging up as you connect.

To measure the current you first switch the meter to a current range of 1 A (or 1,000 mA) or more. You then connect the active wire to one of the appropriate terminals on the meter. You then connect the other appropriate terminal to the battery positive.

The appropriate terminals - meters differ a little, if yours is like this one (click on the symbol in the bottom RH corner of the picture for a larger one) the only range that will suit is the 10 A one - the terminals to use are the 10 A and the common terminals. Connect one of these to the wire to the outlet and the other to the battery positive. It does not matter whichway around, if you connect it the wrong way around the readout will indicate a negative current flow but the reading should be the same.

WARNING, when using the 10 A range be very careful not to touch the leads one onto a positive rail and the other on a negative rail - if you do you will produce some smoke and tears. There is no protection from battery voltages across the 10A terminals. If you are on the mA ranges there will probably be a fuse in the meter that will save the day but there is none on the 10 A range.

Dave Jezza · Veteran Member

Hi PeterD

Reading was 0.01 whatever that means :)

PeterD · Guru

Dave, I suspect that was indicating 100 mA being drawn from the battery by those USB sockets.

Dave Jezza · Veteran Member

Thanks again PeterD, so effectively there would be drain on the battery if the sockets were left connected when parked up. I've already fitted allegator clips to stop the issue.

Cheers

Dave

T1 Terry · Guru

When I connect them up to smaller systems I include a fuse box with a fuse just for each device that has a parasitic load. The one that catches most people is the inverter, even though it is turned off it still has a constant parasitic load. The fix for more complex systems is a battery disconnect, then there is no long term drain, I'd imagine the battery self discharge would be greater than the drain load from the USB sockets, the clock and memory on a radio would be similar, the vast box has quite a solid draw and so on. It's either a case of shutting the whole system down or leaving it running including the solar to top the battery up as required.

T1 Terry

Jaahn · Guru

Dave Jezza wrote:
Hi PeterD

Reading was 0.01 whatever that means :)

Hi smile

Not wanting to be a smart ar*e but when I went to school that was 10 milli(amps?) hmm A more likely drain I would think for the USB ports.

Jaahn

PeterD · Guru

Jaahn, when my meter is on the 10 A range a reading of 1.000 is a 10 A current. a reading of 0.100 is 1 A so .01 would be 100 mA. The OP said "Just connected the empty socket wires to the battery and quite a bright little spark occurs when tapping the connectors onto the pole." I would not have though 10 mA would have produced much of a spark.

Jaahn · Guru

PeterD wrote:
Jaahn, when my meter is on the 10 A range a reading of 1.000 is a 10 A current. a reading of 0.100 is 1 A so .01 would be 100 mA. The OP said "Just connected the empty socket wires to the battery and quite a bright little spark occurs when tapping the connectors onto the pole." I would not have though 10 mA would have produced much of a spark.

Hi PeterD smile

Well I have never seen a digital meter which need a conversion factor to be applied to the reading ?? I thought the idea of a digital readout was the instant accurate answer. Certainly is on the 4 I have, and on all I have used.

However I did get mine out and read current draw on two items. The first is a simple plug-in to a ciggy socket usb converter. The second is a multi ciggy socket with 2 usb outlets(one US hmm ). Both drew about 9milliamps. They both have an LED to indicate power is available, and I guess that draws most of that 9ma. When reconnected after sitting for a while there was a noticeable spark. Charging those capacitors I guess as said. A cheap digital meter is too slow to read that initial surge.

Jaahn

-- Edited by Jaahn on Sunday 13th of November 2016 05:28:22 PM