Wouxun KG 679E Transceiver Uses 1.2mA When Off

Doesn't sound that bad to me.

How long would your 1300mAh battery retain a full charge, if it were removed from the radio?

And what type is it?

Does the operator's manual address this?

Have you contacted the seller/supplier/manufacturer to ask them?

Go here:

Basic to Advanced Battery Information from Battery University

What I dont get is what would it need 1.2mA for when off and doing nothing at all?

How long the battery would hold charge is a good question... its a new li-ion battery so I would expect 5% to 10% discharge per month but I have not experimented since the measured current draw would account for observed battery depletion over a number of weeks. Operators manual says nothing.

1.2 mA in OFF state does not sound like a problem, particularly if the OFF switch is a "soft" OFF or standby state of a microcontroller. In this state the microcontroller must still scan and execute a program looking for the ON button to be pushed. Without knowing a lot more about the architecture of this radio I cannot say anything else.

To Redfred:-

You are absolutely right, many modern electronics never switch off "completely".....

To the OP:-

There are ways of doing it so that no drain happens, but many design teams cannot be bothered to learn how....they assume in daily usage, it will never be noticed.

Also, some electronic units have to maintain a memory (also an old fashioned method in todays world) of a setup or values, radios would be a prime example.

Most modern car radios for example have to have a permanent +ve link to maintain the saved stations, for this mobile I cannot say....try removing the batteries for a day or so and see what gets lost. If nothing important gets lost, try slipping a piece of plastic between the unit and the battery contacts, though battery self discharge may be about the same in the end!!!

Its always a good idea to check such things out before purchase if it might be a problem.

I just looked at the data sheet and I am almost certain the standby it talks of is when its on but is squelched (if thats right word). It would be a very large current draw if it were using 50mA when off. Yes, it is software defined but would it not use non volatile memory for its settings. I have not looked inside unit but the on/off switch seems like a real one and not a "soft" implemented one.

As RAMConsult said, this is a software-defined radio, so there is a microprocessor in there. When you turn the switch to "ON," you don't want to have to wait for it to boot up, do you? You want the radio to turn on and start working immediately. So the processor needs to be running and ready all the time. I'd say 1.2mA is pretty good. Most people store their radios sitting in the charging stand anyway - that way it will be at full charge when you grab it and go.

off hand I would say that does not sound right because lots of items with microprocessors dont keep it running when off and it takes no time at all to get going. I have a geiger counter that has software in a eeprom and switches off fully and gets going swiftly. david

Not every micro-controller is designed to minimize standby current draw and not every designer bothers to use the program settings to get into that state. Many different reasons can be the cause for this. These reasons can be from valid engineering design choices, to market flexibility, to simple laziness of the design team and all stops in between.

Yes, the term standby is ambiguous, and the context doesn't tell us whether it's off or squelched. But there may be another explanation. Sometimes these devices use a pulsing system for keep-alive purposes. Depending upon your meter the period may just be within the sampling window so you read 50ma when in fact the duty cycle is only 5% making the reading look high. If you have a scope or an analog milliammeter you'll get a better idea of what's going on. I agree that it seems excessive, maybe they meant 50μA with the unit switched off.

When its ON and squelched I get 72mA current draw which is much more near the 50mA standby they mention in manual. I do have a scope ,of sorts, so I could have a look tommorow and see what the waveform looks like. david

You should also remember that the old reliable Fluke 25 is not a true RMS meter. So only a sinusoid waveform and DC will be accurately measured.

Thanks, that is exactly the sort of thing I overlook. I do like my fluke 25.. got is so cheap on ebay too! david

Although the Fluke 25 is not true RMS it is detecting some level of leakage.

The radio is software defined and may well require a small "off" current to retain settings such as system time and settings. When this is a requirement, it is common practice include in such a device, an internal auxiliary battery, typically the silver oxide button type.

It is also likely that the current draw wont be mentioned in the user manual. Also the manufacturer point of contact or sales staff probably won't know anything about the current leak either.

If the device has a leakage, you would normally notice this current to decrease as the battery voltage decreases over time but your device uses LION technology so the discharge voltage remains almost constant until it's safe capacity is almost exhausted. Then it's output voltage sharply drops to zero due to internal cut off cct's.

A couple off things to do may satisfy your curiosity.

You could ask the sales staff of your device if you could take a look at another identical device, place a battery in and observe what sort of "off" leakage current you get.

If you have access to a reliable regulated power supply. Set up the output voltage and current limit to match the battery's specifications. Then couple the power supply leads to your device. Verify your radio works. Turn it "off", place your Fluke 25 in line with one of the leads as you did before when you did your original leakage test. Test again for 1.2mA. If you get this value in the off state, you can carefully drop the power supply voltage slowly by 10% at the most. This should be enough to make the following observations:1) You may find the current leakage drops. In this case your device is likely to have a fault-earth leakage.

2)The leakage current remains the same despite the drop in supply voltage. This indicates that your device requires a "standby current". It has pulse width modulation regulation (switch mode power supply) increasing duty cycle as you drop the supply voltage. So the 1.2mA "leak" is highly likely there to keep it's processor and /or volatile memory functional.

Hope this helps.

MM

I am not familar with your particular device however we have several of this type of device and they all have satellite GPS tracking that is powered at all times.

Logic & Reasoning for this option;

1. Safety concern for tracking the location of the user in case of an emergency situation.

2. Tracking and identifying FCC regulation violations for enforcement at a personal level.

3. Tracking and location for theft deterrent.

I suggest you contact the manufacturer technical support group to obtain the answer to your question if you want to be sure.

Most modern Cellphones have same/similar characteristics and few worry about them, they just remember to plug in the charger at regular intervals.

By the way, I am personally against putting any device, even an electric toothbrush, back on the charger when not in use. Most rechargeable batteries have a finite number of charges and leaving the device out of the charger till needed appears to reduce the charge cycle usage and prolong apparent battery life.....