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Author Topic: Cordless phone batteries don't last  (Read 3746 times)
KE2KB
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Posts: 265




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« on: January 06, 2015, 11:25:32 AM »

Hi;
I have a Panasonic cordless phone system with 3 handsets. Recently, I had to replace the rechargeable batteries in two of the handsets - after owning the phones for about 3 years. I decided on the Eneloop AAA batteries, since I had been using them with excellent results in other devices.
Now, less than one year later I find that the batteries in one of the handsets are fried. The phone is displaying a message "charge batteries for 7 hours", and when I put the Eneloops from that handset into my Maha MH-C9000 charger, it refused to do anything with them. When I tried the Refresh & Analyze mode, the charger displays "high" and stops immediately. If I try only discharge, it reports "done" immediately.
I have two Eneloop chargers - neither will charge these batteries, but will charge other Eneloops. I have concluded, based on my observations, that the batteries are fried.
So I did a Google search and came up with a post by someone on this problem - the answer was that the cordless phone charging stand is overcharging the NiMh batteries. This is the way most cordless phone chargers work. They would rather ruin the batteries than take a chance on having them run down and end a call prematurely. Then, when the batteries run down, the phone manufacturer can blame the battery manufacturer, especially if the user has replaced the batteries himself, and not used the manufacturer's preferred brand of battery.

What I would like to do is disable the charging circuits in the phone stands and just set up a recharging schedule or wait for the phone to indicate low battery, and recharge the batteries in my Maha MH-C9000. We have a wired phone on the same line, so it's not like we would lose our phone service completely. I will only need to remember to check the status of each handset's battery on a regular basis, and swap out a set of charged batteries while I recharge the ones from the handset.

Just an FYI: The batteries that were fried were in the handset that sits in the base unit. I don't know if there is any difference in the charging circuits, but it is a thought.
For now, I am going to unplug the two charging stands used by the two handsets that are placed away from the base unit. I will then disable the charging circuit in the base unit.

If anyone has a comment or suggestion, please tell me.

Thanks
Frank - KE2KB
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KC2QYM
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Posts: 367




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« Reply #1 on: January 06, 2015, 12:45:34 PM »

I went through this with my cordless phone and rather than re-engineer the darm thing I just placed all my wired phones back into service.  All the existing outlets in four rooms now have a phone connected and I'm never that far from a phone in my house; I eliminated a walrat as well.  So what if I don't have message recording....only the important people in my life have my cell phone number.  All the phone phishers and scam artists can't even leave a message anymore....ha...ha...ha.  Sometimes low tech is the answer.
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KE2KB
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Posts: 265




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« Reply #2 on: January 06, 2015, 01:26:45 PM »

I went through this with my cordless phone and rather than re-engineer the darm thing I just placed all my wired phones back into service.  All the existing outlets in four rooms now have a phone connected and I'm never that far from a phone in my house; I eliminated a walrat as well.  So what if I don't have message recording....only the important people in my life have my cell phone number.  All the phone phishers and scam artists can't even leave a message anymore....ha...ha...ha.  Sometimes low tech is the answer.
I like that!
I still have wiring everywhere it is needed, but don't have the wired phones anymore.
For now, I just unplugged and removed the wall-warts from the two remote units and cut the red wire (or is that the blue wire <ha ha>) from the pcb to the charging cradle on the base unit. I installed a fresh pair of Eneloops in the handset with the dead ones, and will swap out one set of the old ones in the other handsets to run refresh & analyze on the MH-C9000 to see if those Eneloops still have any life left. Finally, I will create a schedule in Outlook to remind me to check the batteries in the handsets.
Unfortunately, even with freshly charged Eneloops in the handsets, the display says "recharge battery for 7 hours". I measured the voltage at the batt terminals with the handset on, and it read 2.77V.
That's above the nominal 4.4V that for AAA, indicating a good charge. Yet the stupid charging system says it needs a charge. Not surprising that the batteries got fried.

This is the reason I now use Eneloops in my Yaesu/Vertex VX-150, FT-530, and as the second battery for the FT-60R I just bought. I had purchased an FNB-83xh pack for the VX-150 back in 2010 from Batteries America, and was getting excellent results from that pack (but using the radio mostly for receive) until several ago when I noticed that the battery pack wasn't charging properly anymore - it would cause the CD-30 desktop charger to terminate prematurely. probing the individual batteries in the pack, I found that four out of six were fried. I could not revive them by any means. So I trashed the pack and bought another set of Eneloop AA's - the latest version by Panasonic.
When I purchased the FT-60R, I bought another FBA-25 AA cell holder for the FT-60/VX-150. Now I have the option of either the FNB-83 that was supplied with the FT-60R, or the Eneloops - for either the FT-60 or the VX-150.

I am happy about one thing regarding the Panasonic cordless phone - it came with removable AAA batteries, and not the permanently installed ones that many other devices come with.

I'm curious to know whether the newer cordless phones have smart chargers - to comply with California laws (and thus applied to most electronics sold anywhere in the US), which apparently require chargers to shut down completely when the battery is finished charging. MY FT-60R manual has an insert to the manual that states the battery pack cannot be recharged through the EXT DC power jack on the radio because of California energy laws. The same law should apply to cordless phone charging circuits as well. But my phone is at least 5yrs old, and I suppose that law is newer.

I might consider your solution as well. I would just need to wire up the Optimum Voice phone line to the house phone wiring.

Frank - KE2KB
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G3RZP
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Posts: 6307




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« Reply #3 on: January 06, 2015, 02:06:44 PM »

It is worth considering what happens when the power goes out. Does the cordless 'phone still work? What happens when some weather or other disaster strikes and the cell 'phones go out?

The fact you have a 2m handheld doesn't guarantee that the repeater will hold up or anyone is listening....so a wired 'phone is the last line of communication. Otherwise, an HF rig, generator and an HF antenna.....

Admittedly, round here, any reported fault is 'tested' and is ALWAYS, according to their tests, in the property. Bit tough on the technician who came out and found the fault on a pole 2 miles away - on a morning when it was -3 degrees C. But then....I live out in the country...
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NO2A
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« Reply #4 on: January 06, 2015, 05:52:58 PM »

Last year we had our landline yanked right off the house from a snowstorm. Often we get static on the line. The tech told me the maintenance won`t be what it once was. I don`t know how much longer we`ll have a real landline. I always liked the corded phones.
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KD8KCH
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« Reply #5 on: January 06, 2015, 06:56:47 PM »

For a simple solution just don't leave them sit in the charging cradle. Mine just sit on the counter until the battery indicator shows low and then I re-charge, same batteries now for 4 years.
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W8JX
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Posts: 8236




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« Reply #6 on: January 07, 2015, 10:16:20 AM »

For a simple solution just don't leave them sit in the charging cradle. Mine just sit on the counter until the battery indicator shows low and then I re-charge, same batteries now for 4 years.

Yes this is cause of short battery life and a solution. Kinda silly to use Eneloop batteries and keep them on a constant charge. 
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You can embrace new technology and change with it or cling tightly to old technology and fall further behind everyday....
K1DA
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Posts: 653




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« Reply #7 on: January 09, 2015, 10:34:19 AM »

Last year we had our landline yanked right off the house from a snowstorm. Often we get static on the line. The tech told me the maintenance won`t be what it once was. I don`t know how much longer we`ll have a real landline. I always liked the corded phones. [/
  I've been told the same thing about a long term landline noise problem.  Fewer subscribers mean less spent on plant maintenance and upgrades.  Soon more folks leave because they have somewhere else to go and the service is degrading.    This is, of course, a "good" business plan. 
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KD0REQ
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Posts: 1445




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« Reply #8 on: January 09, 2015, 11:03:28 AM »

verizon wants to start rolling the landline business off, a piece at a time, to somebody else.  centurylink, on the other hand, got big and tough buying little castoff pieces of bell and independent phone systems.

everybody's landline take and revenue is going down, and long term view appears to be selling VoIP with their bundles of services.  until the FCC classifies data service as an essential service, though, don't expect backup power along the chain outside of the COs.

as for those phone batteries... there is such a thing as a high-rate fast-charge extra capacity NiCad, and that's what could be in those battery packs.  that's NOT what you will find in a general-sales type rechargeable.  you have to order them from someplace like DigiKey.
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N7EKU
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Posts: 304




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« Reply #9 on: January 09, 2015, 01:46:02 PM »

For a simple solution just don't leave them sit in the charging cradle. Mine just sit on the counter until the battery indicator shows low and then I re-charge, same batteries now for 4 years.

Yes this is cause of short battery life and a solution. Kinda silly to use Eneloop batteries and keep them on a constant charge. 

For sure,

Users need to be careful when replacing old rechargable battery packs.  The problem is that the capacity of the batteries keeps going up an up (which is great in itself).  However the higher capacity battery packs need to be charged at a higher rate, and the old charging systems won't do that.  The reason for needing the higher charge rate is that it is necessary for assuring that all cells in the pack attain a full charge and they need a certain rate to do that.

So you shouldn't "upgrade" your batteries unless you upgrade your chargers.  The hard part sometimes though is to still find lower capacity batteries that are in good shape.

The enloops are a great option if you just use them as described previously -- don't leave them on the cradles, use them until they run down, then charge them on a modern charger.

73,


Mark.

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N9AOP
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Posts: 221




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« Reply #10 on: January 09, 2015, 02:26:34 PM »

Cordless phones could be made with intelligent lithium batteries same as the cellphones use.   I have a pair of Uniden cordless phones which I bought at Wallmart for $8.00.  At these price points there is no way they will put better battery systems in the phones and if they were selling something decent at $25-$50 they wouldn't sell enough to make it worth while.

Just order a handful of tabbed cells and change them out when necessary.
Art
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K5TED
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Posts: 1029




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« Reply #11 on: January 09, 2015, 07:27:45 PM »

I just replaced the batteries in my AT&T three handset cordless system. Each phone has it's own charge stand. The set is 5 years old. I put in the recommended replacement type, bought on Amazon for $12.99 shipped for all three battery packs.

What sort of cordless handset uses regular AA batteries? Why? Cordless phone battery tech is pretty mature. Why re-engineer it?
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KA4LFP
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Posts: 130




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« Reply #12 on: January 11, 2015, 08:11:14 AM »


Admittedly, round here, any reported fault is 'tested' and is ALWAYS, according to their tests, in the property. Bit tough on the technician who came out and found the fault on a pole 2 miles away - on a morning when it was -3 degrees C. But then....I live out in the country...

Tell me about it.
I reported a T1 down for one of my work remote sites, knowing the problem was that, along the road leading to the site,  a contractor for an apartment complex had been tying the complex into the water service out in the street, and had successfully backhoe'd a 500 pair buried cable containing the pair by T1 was on.  They'd completely failed to do a ULoCo (or more to the point, the ULoCo markings were in English, a language not spoken by any of the onsite backhoe operators...)


AT&T had the note in their ticket that a 'major cable fault' had occurred at the address of the new construction, 5 miles from where my site was.

But sure enough, when they closed out the ticket, the reason stated for the problem was
"bad pair leading from demarc to customer CPE"
(for those not familiar, that was them saying the wire inside my building leading to my router was the problem)

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