Phone battery pack redesign / more mAh

[toysarefun]

I have your basic cordless, I noticed they are putting larger batteries in these things, in fact it has 3 AA batteries. So, the phone is about a year old and now the talk time is about 30 minutes tops and the phone goes beep and the battery is dead, can't even say goodbye, junk.

Well, the three batteries together are rated at 600 mAh. I'm like forget that, and tired of replacing these costly little things. I made my own battery pack out of 900 mAh Ncad AA batteries for a total of 2700 mAh.

Fire hazard?, to many amps?, the phone works great. Took electronics in tech school but that was 23 years ago. Figured I'd ask how others handle dealing with cheap battery packs, and generally how crazy can you get regarding adding more amperage, what's overkill, dangerous, etc.

 

[MikeMl]

The chargers in those things are cheap and nasty; they dry out the batteries by chronically overcharging them while the handset is parked in the cradle. If you take the handset out of the phone, and only put it in the cradle about two hours a day you will get 3X to 5X the battery life.

 

[crutschow]

Going to the higher capacity batteries should be no problem. It will just take longer to charge but should give you 1.5 times the talk time.

Incidentally, putting the batteries in series does not increase the mAh rating. It's still equal to one battery (900mAh).

 

[audioguru]

Cheap Chinese old fashioned Ni-Cad battery cells are rated at 600mAh but produce 300mAh. They go bad in about 1 year.
A modern name-brand AA Ni-MH cell is rated at and produces 2500mAh which is 8.3 times more. It lasts for years.

A new phone complete with an obsolete Ni-Cad battery costs less than a replacement obsolete Ni-Cad battery.
I have not seen an assembled modern Ni-MH battery for sale.

 

[toysarefun]

Thanks for the suggestions, and correcting me regarding amps. I've noticed when trickling batteries the charger will cool off eventually when the charge tops all the way up, seems like the phone cradle finally cooled off which is how I guess I'll figure out how long charge time might be. These batteries I used are some no name that say MH on them, they were never used/charged, came with an old breast pump that I recently junked out.

 

[audioguru]

If charged at a current that is its mAh rating/10, a Ni-Cad cell gets cooler until it reaches a full charge then it heats.
A Ni-MH cell heats slowly all the time it charges then heats more when it is fully charged.

 

[DirtyLude]

I've done this with a Panasonic 900Mhz phone and it worked really well. Lasted about 3 years. I've been too lazy to build another battery pack so it's been sitting in a corner for a year or so.