Do cordless phones have smart chargers?

[jzmtl]

My cordless phone battery pack is almost dead, so I thought about making a new one myself. I put my multimeter between the two charging leads and reads about 100 ma current. So do phones have smart chargers? The current pack is about three years old so I guess it must have because no way nimh cells will survive that long under 100 ma current.

 

[Marduke]

Most cordless phones I've seen just use a dumb constant trickle charge on Ni-Cad batteries. But then again, I haven't bought one in about 5 years.

 

[Mr Happy]

My cordless phone has a NiMH pack. It must have a smart charger because if I use the phone for an hour and put it back in the cradle, the batteries get warm from recharging. But if I leave it in the cradle without use, the batteries remain cold.

 

[VidPro]

yup dum and slow, if its readin 100ma, They are usually seires packs, so something would need to balance the pack out anyways, so there is nothing "wrong" with them being dum and slow. they can also have a Voltage MAX, where it slows down even lower than the 100ma when full.

we always replace the ni-cds (600-800) with ni-mhy (2000-2500) cells , giving 3 times as long to charge and 3 times as long running.
then about every 6months we leave the phone off the hook till it has gone mostly down, purposfully, that gives them a chance to cycle.

the phone that gets USED and left off the hook (cycled), works great always, and when i cycled them it runs the longest, the phones that just park and dont ever get cycled, i have to cycle them more to get them back to par (they are off hook for 2-3 weeks to cycle).

at any rate they have been working for 8-10 years now, slow and dum, probably below 80% capacity, but still does everything it needs to do.

they say that ni-cds could handle the continual topping charge better, but for the 3x capacity of the ni-mhy the charge is even lower and slower, which causes even less damage. plus the ni-cds in them (and available for replace) were probably cheap junk anyways.

 

[NA8]

I picked up a Panasonic KX-TG1033S Dect 6.0 phone set recently. Each handset uses two individual Nimh AAA batteries. Charge them in their base or on your charger.

http://www.amazon.com/dp/B000LYAX1G/?tag=cpf0b6-20

 

[digitor]

My cordless phone battery pack is almost dead, so I thought about making a new one myself. I put my multimeter between the two charging leads and reads about 100 ma current.

Putting your meter between (across?) the leads will not tell you the charging current. You need to measure that by putting your meter in series with the cells - but that will not be perfectly accurate, because of the voltage drop of the meter. A better way is to use a DC current clamp, which will tell you exactly what the current is, but be aware that the current will vary according to the state of charge of the pack at the time you make the measurement.

Cheers

 

[WildChild]

I have a 900 mHz GE phone that had a NiCD battery that lasted 1 year... I was always running it until I got the low battery warning then charged it for 12 hours (600 mAh). At the end, I was getting only 1 day of charge. I replaced it with NiMH batteries, first with some Sanyo 2500 mAh that had a high self-discharge rate, the pack lasted 1 week but batteries came very unbalanced. I made last week a pack with Duracell 2650 mAh cells. It has been more than one week and the pack is well balanced and still going strong. I usually charge those NiMH pack for 48h then I completely discharge them before charging again and since I made the Sanyo pack I don't think I'll buy a NiCD pack anymore. The cradle charges at 70 mA. I only hope those Duracell won't develop a high self-discharge rate too fast.

 

[rizky_p]

most of my panasonic cordless phones are using(i think) a dumb charger. Weird think is when i left the battery drained, it wont charge again. I have to buy a new pack. It happened to me several times.