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Stranger problem: BCD396XT sometimes get hot when charger attached

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wireless_friendly

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Stranger problem: Uniden BCD396XT sometimes get hot when charger attached

Hi all!

I have received my brand new Uniden BCD396XT.

First thing I have moved Battery Type to Alkaline position and inserted NiMH rechargeable batteries (because I always charge batteries in superb LaCrosse BC-900 and never inside scanners).

I powered it on, turned on backlight (Infinite mode) and BCD396XT connected to the power adapter (just because I am at home and don't like waste batteries power when near power outlet).

After approx. 2 hours of operation in nylon case I notice light wormed electronics smell. I have removed scanner from case and notice that it warm (approx. 100..110 degrees by Fahrenheit / 38..43 by Celsius). When I removed batteries, I notice that they also warm (all 3 pcs.) to the similar temperatures. I double checked, but Battery Type in Alkaline position! I am absolutely sure:



I have connected Fluke multimeter to the battery terminals and begin very simple experiment - connecting and disconnecting power adapter when Battery Type in Alkaline position. And I find out that voltage increases on approx. 0.15-0.20 V when power adapter attached. See pictures below.

Without connected adapter:



With connected adapter:



Questions:

1. What sort of devilry is this?
2. Anybody have similar heating problem (maybe only sometimes, not always)?

If somebody want told me that my BCD396XT is broken: I will say - NO, because my BT330T have the same issue (excluding wormed electronics smell).

The problem appears not always and I cannot understand the reason of its anomaly.

Any conscious ideas will be appreciated.
 
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DaveIN

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#6
From reading post on this similar subject for the 246 and 396 classic, the outcome was that the switch should disconnect the charging circuit when placed in the Alkaline setting. Did you try to measure the output without the batteries in circuit?
 

DaveIN

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#7
I guess I should mention that I am not an advocate of charging the batteries in the radio and use an external La Cross BC-900 to condition all my batteries with exception of the two 15 minute chargers I have for quick runs or photography use. I also only use the handheld with batteries and take it from place to place. The little amount of time I have had it on the adapter, with batteries in place, I did not notice any overheating or smell.
 

daveharpe

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#8
Maybe a grounding issue?

Here's a guess. When you connect the power adapter, the ground reference for the radio will change...the radio will be grounded through the charger and not self-grounded. This would change the voltage reading when you plug in the adapter because you're measuring the voltage relative to a different ground.

Is it possible that it's not related to the batteries at all? Try pulling the batteries out of the radio (put the battery door back on) and do the same thing you describe...run the radio for a few hours with backlight on infinite while connected to the wall...then see how hot the radio gets. Those LCD backlights put off a lot of heat, so I could see it heating up the radio after a couple of hours.

Dave
 

wireless_friendly

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Here's a guess. When you connect the power adapter, the ground reference for the radio will change...the radio will be grounded through the charger and not self-grounded. This would change the voltage reading when you plug in the adapter because you're measuring the voltage relative to a different ground.

Is it possible that it's not related to the batteries at all? Try pulling the batteries out of the radio (put the battery door back on) and do the same thing you describe...run the radio for a few hours with backlight on infinite while connected to the wall...then see how hot the radio gets. Those LCD backlights put off a lot of heat, so I could see it heating up the radio after a couple of hours.

Dave
Try to do the same with power supply and any battery (i.e. connect battery negative terminal to negative wire of power supply and leave battery positive terminal useless). And you will see that turning on/off power supply don't affect on voltage on battery terminals.
 
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#10
And I find out that voltage increases on approx. 0.15-0.20 V when power adapter attached.

What sort of devilry is this?
A no load voltage of 1.28 volts per cell and a loaded voltage of 1.21 volts per cell is perfectly normal.


When you connect the power adapter, the ground reference for the radio will change...the radio will be grounded through the charger and not self-grounded.
Not true and even if it were, it would have no effect on the OP's voltage readings.
 

mike_s104

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#11
Almost the same thing happened to my 396XT. I checked the switch right after I removed it from the box before placing the batteries in the unit. I DID charge the batteries in the unit over night. The next day I set it up with an attic antenna and Serial-to-USB adapter and let it run for a few days inside a new nylon case for a 396T. After about 2 days plugged in and running with the batteries in the unit (which should have stopped charging), I got to work and noticed that the ProScan stream was up but I was getting "No Response". I RDPed into my PC and everything looked OK. When I got home, I saw it was off. I thought it was something weird and turned it back on. The next morning, it was off again. I turned it on and went to work. Got home and it was on then I checked it 15 mins later and it was off. I tried to turn it on and it would not come on. I removed the batteried and still nothing. I removed it from the case and waited a few mins. It finally came on and has been on for over a week without issue. I think the problem was heat inside the case and it turned itself off and would not come on until it was cooler.
 
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GTO_04

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#12
I am assuming it's OK to run the 396T or the XT on just the wall wart without the batteries, correct?
When we do firmware upgrades it is without the batteries installed.

Some older scanners, like the 245, IIRC it was not recommended to run it on the wall wart without
batteries installed.

GTO_04
 
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#13
Now you guys have me worried. My XT runs nearly 24-7. I have an ac adapter at work that it is plugged into all day, then at night it is plugged into another at home. Only when I am between work and home or have it with me on the go is it not plugged in. I just pulled it out of the nylon case and the batteries are very hot to the touch. Is this going to shorten the lifespan of my expensive toy? What is the most convenient way to always have portable power without having to open it up and change batteries all the time?
 

wireless_friendly

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Now you guys have me worried. My XT runs nearly 24-7. I have an ac adapter at work that it is plugged into all day, then at night it is plugged into another at home. Only when I am between work and home or have it with me on the go is it not plugged in. I just pulled it out of the nylon case and the batteries are very hot to the touch. Is this going to shorten the lifespan of my expensive toy? What is the most convenient way to always have portable power without having to open it up and change batteries all the time?
Ok, it confirms that described above problem really exist.

Your XT have any smell like is warmed electronics (not a great, but easy noticeablew when your nose is in affinity from the keyboard)?
 
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#15
Ok, it confirms that described above problem really exist.

Your XT have any smell like is warmed electronics? Strongest smell is near the keyboard (but not near speaker grill).

I don't notice a smell right now, but I just plugged it back in after having it out of the case and off the charger to check it out. I'll check it later in the day to see.
 

wireless_friendly

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#16
The strangest that heating appears not always.

Often heating is not present even if XT in a case and backlight is enabled (Color = White, Mode = Infinite, Dimmer = Middle).

I do not understand the reasons of this.
 

mike_s104

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#17
The strangest that heating appears not always.

Often heating is not present even if XT in a case and backlight is enabled (Color = White, Mode = Infinite, Dimmer = Middle).

I do not understand the reasons of this.
we're talking about being on the power adapter for an extended period of time even when charging is over or not charging at all.

after thinking about it, the one time I caught it right after it shut off, I did smell something from it.

mine has been running 24/7 since the last time I had it happen a few weeks ago.
 
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#18
Now you guys have me worried. My XT runs nearly 24-7. I have an ac adapter at work that it is plugged into all day, then at night it is plugged into another at home. Only when I am between work and home or have it with me on the go is it not plugged in. I just pulled it out of the nylon case and the batteries are very hot to the touch. Is this going to shorten the lifespan of my expensive toy?
So you've been starting 14 hour charging marathons every time you plug your scanner in. You have already ruined the cells; their max runtimes will be dropping into the gutter. At least your expensive toy is probably not being harmed.


What is the most convenient way to always have portable power without having to open it up and change batteries all the time?
Uniden doesn't give you a convenient method. You can either charge them externally or run them down before plugging in the AC adapter - hold off on plugging in the adapters at home and at work until the low battery warning starts. If that doesn't give you enough juice for the trip home, try plugging in at the office halfway through your shift.
 

wireless_friendly

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we're talking about being on the power adapter for an extended period of time even when charging is over
No! We are talking about situation when Battery Type switch in Alkaline position, i.e. no charging.
or not charging at all.
Yes.
after thinking about it, the one time I caught it right after it shut off, I did smell something from it.
Welcome to the club :)
 

hfxChris

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#20
So you've been starting 14 hour charging marathons every time you plug your scanner in. You have already ruined the cells; their max runtimes will be dropping into the gutter. At least your expensive toy is probably not being harmed.
So then what's the point of the switch in the battery compartment, if not to disable the charging circuit?
 
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