Cordless phone batteries

tylerdurden

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My cordless phone (panasonic) has a nicad battery pack that appears to be made of three AA flat-top cells. It's a measly 850ma. Replacements are all 850ma as well. The top of it has some weird plastic thing that is needed to make it fit into the phone correctly. Is there someone that can take this pack, disassemble it, and use the plastic key part to build a new pack with higher-capacity cells? I assume it will take longer to charge the battery if higher capacity cells are used.

What would happen if I used NiMH instead? That would give me a higher capacity, but would the charger be able to handle it?
 

kitelights

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Battery Station builds packs and could conclusively answer your other questions.

The last cordless I bought, I got because it had NiMH (also Panasonic).
I was led to believe that the charger is different for NiMH than the NiCad models. Personally I would stick with the NiCad cells, but use higher capacity if available.

Replacements are cheap compared to custom paks, if not just for the shipping involved. You can get them in WalMart and Circuit City for $8-$15 and they last 1-2 years. After 1 or 2 replacements the phone technology is old and you'd probably want to upgrade.
 

idleprocess

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My understanding of NiCds is that they can be trickle-charged endlessly without damage, unlike NiMH cells that require monitoring of cell state and some defined termination of charge.

There's a chain of stores in my area called Batteries Plus that has the equipment and personnel know-how to assemble custom packs and reassemble almost any imaginable pack at a reasonable price. They seem to stick to cell phone and laptop packs, but I'm sure they could do a cordless phone easily enough and recycle most of the connection hardware. I don't know if it would be cost-effective since the replacement-pack business is actually competitive...
 

tylerdurden

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It's probably not worth it if I have to stick with nicads, since the highest capacity nicad AA flat-top I've seen is 1100mah. I'm not going to want to pay extra for such a small increase in capacity. If I could use the NiMH at 2300+ mah, then I'd be willing to fork over some dough for custom pack assembly. Oh well. I will probably upgrade as soon as I can find a two-line expandible system at 5.8GHz.
 

cobb

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Thanks for the answers, I have had the same idea too. My cordless phone seemed to sucked its battery since day one. It got to the point a 5 minute call made the lower battery alarm go off. After 4 years I went to radio shack and bought a new pack. Man, I can use it a week on a charge. It must of came with a dud battery.
 

andrewwynn

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cobb.. it's really easy to 'kill' a NiCD batt if you use it before the first good solid charge.. i've seen it a dozen times...

I have an AT&T cordless phone that kicks butt.. it comes with NiCD but has an avil. NIMH which is really expensive if you buy in a store but i got 3 for $25 on eBay.. it charges a bat in the base and will of course RUN off that battery if power fails.. in any event.. it charges either NiCD or NiMH so i don't know what the differences are in the charger.. but the NiMH do much better in the phone.

the phone was $200 with 1 handset and the spares were $85.. but i found a dealer on eBay that had the phone for $100 and handsets for $55.. i couldn't be happier with the phone.. don't believe the 5.8 hype.. 2.4 will do the job just fine.

I don't know what will happen if you swap NiCD for NiMH in an existing model, but i think worst case the bats will just lose charge.

hmmm.. just realizing.. i think my phone uses 3 series bats.. that will be 3.6V nominal.. i could use 3 of my LiON AAAs and get much more storage.. oops darn.. it uses 2 AAs.. oh well.

-awr
 

wptski

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Since charging Ni-CD and Ni-Mh is supposed to be different. I have a MAHA MH-C777PLUS and the newer PLUS-II both have two settings, Li/CD-MH. How does it know which?

I do know that in Li the charging rate is 400ma and in CD/MH it's 800ma.
 

tylerdurden

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[ QUOTE ]
andrewwynn said:
don't believe the 5.8 hype.. 2.4 will do the job just fine.

[/ QUOTE ]

What's the 5.8 hype?

If "the job" is "interfering with my wifi" then yes, 2.4 does it just fine.
 

cobb

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Your cordless phone works in a power failure? Mines dont. I have tossed the idea around to make a back to hook in parallel with the power supply so it would, but never did.
 

andrewwynn

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tyler did hit on one main benefit of 5.8.. my point was to say.. range and quality of sound are as good or better on 2.4.. my base for my 2.4 is 6' from my wireless router and i've never had any interference problem.. even though i use both at the same time from the 2nd floor when both bases are in the basement. i get a little bit of noise if i'm close to an operating microwave.. just some clicks...

cobb: why yes it does.. every one i've ever had has that feature... it charges a battery in the base, but uses that battery to run the base on power failure. i would never buy a phone w/o that feature.

I have the sony 2464 i think it's called.. 2402 handsets.. i bought a 'spare' base station because they don't make them anymore... it's a really solid phone.. comes with hands-free kit as well as having speaker phone built into the handsets.
 

cobb

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I believe mines is a sony with 15 minute tapeless recorder. It was cheap at sams club and 900mhz. I wanted an answering machine fax combo, but it the price was right. I agree with buying a base that is battery backed up for a future machine.

My folks on another note have a speaker phone that takes AA cells. It works regardless of power. Nice and the aas seems to last little over a year before changing. It has a time clock display that sets itself with the phone company.
 

Brock

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Odd, none of the 3 cordless sets I have work without power to the base. The handset will work, but without the receiver powered it doesn't much matter. I have since switched two of our base units over to be charged and powered from our in house 12v bank so now they have power from that even if the grid is out.
 

andrewwynn

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brock.. your cordless phones have a charger in the base for a second battery? bad bad bad designers if it doesn't operate the base when no power.. cool about 12V house bank.. reminds me of something i sometimes.. stole the idea from mabell.. remember back in the 70s when the princess phone came out.. they run power from a power brick in the basement over the second pair (yellow/black).. what some people ignorantly put a second line on if they really like crosstalk.. anyhow i wired up a power brick down in the basement to a third pair in my cat-3 cable i use for phone.. and upstairs i only have on cord for both phone and power (it's two-headed just at the end 5 inches).. it's very neat.. especially since it's a wall-mount and the wire is up inside the wall.

-awr
 

Brock

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I stated that wrong. Just a walwart to the base and you set the handset in the base to charge it. I believe this is the way 95% of the phones are setup? The base has to have power to transmit to the receiver and vice versa. Are you saying some have an internal battery in the base also?
 

andrewwynn

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yes a SECOND battery for the phone.. so you don't have to wreck your battery by constantly trickle charging which is good for no chemistry of battery other than lead acid that i'm aware of... you can just swap batts when one dies... with the added bonus of the spare battery in the base supplying power to the base when wall power is non existent. I wouldn't have it any other way.. my first phone that had this feature i bought in about 1993.

-awr
 
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