Recycle those Rx packs...

[BrianG]

I have an older cordless house phone that doesn't keep a charge anymore. I also have a few receiver packs from converted nitros. Sooooo, a little modification to the phone battery area and a removing 2 of the 5 cells of an Rx pack, and I now have a new phone battery!

It's not perfect, but it works. The Rx pack cells are exactly the same length, but are about 2mm larger in diameter. But that's nothing a little dremel work to the phone battery tray won't fix. And now I have a phone with almost triple the runtime as stock. NiMH pack = 1100mAh, Stock phone pack = 400mAh.

Unfortunately, 6 out of the 10 keypad numbers don't light up anymore, but that's just acceptable collateral damage IMO. Once the [ex]wife moves out, I'll be canceling the land line anyway, but this will work until then...

Can you tell I was bored?

[coolhandcountry]

You couldn't have posted this at a better time. My landline is messing up for battery old and crappy now. Thanks.

I did the same thing about 3 yrs ago - the Sony cordless phone had already been thru 2 rechargeable pacs and got to where you'd get the low voltage beep in less than 5 min talk time. That phone uses full size AAs and I made a pac using 3 2300mah PowerX batts. 3yrs later, it will let the wife talk for over an hr and still not beep. I really think they put cheapiest cells in them possible so you'll have to periodically replace them.

It saved me from buying another phone!

[BrianG]

Some people would just go out and get a new battery, but ever notice that a whole new phone is just a few bucks more than just the battery? What a ripoff!

Anyway, hope it works for you as well as it did for me!

[BrianG]

Well, considering the price of replacement packs versus the whole phone (which includes the pack), it makes sense they would put cheapies in there.

Some of the problem in my case is that the kids don't ever put it on the charger so it drains to the point where the phone charger won't even charge it anymore. I have to put the pack on my R/C charger to get the voltage back up to an acceptable level. But, discharging that low isn't good for the batts. I thought about putting in a couple germanium doides (0.3v vs 0.7v drop of silicon diodes) in parallel to each other back-to-back (but flipped) so that the voltage drop will trigger the phone cutoff circuitry a little sooner, yet keep the packs in a better state. Something for another day I guess.

[BP-Revo]

Yea...our home phones were running out and my mom wanted to buy new phones...

I told her to save the money and just let me spend 20 bucks buying some AA's, some small gauge wire (Deans12awg would have been overkill LOL - and wouldn't have fit).

Now the phone's last longer with 1 bar left than they did when they had a full bar. (Went from a 600mah pack to something over 2000...it was quite an increase).

Just tonight I was talking with my dad about making a pack for our new camera and charging it on our rc chargers, he bailed and still wants to use the crap wall charger. Sigh, he just wants to stick with what they know and what's safe despite the fact that whatever I make would be much better.

[BrianG]

Eww, those wall chargers are crap. They either rely on the output resistance of the tiny transformer inside to limit the charge current, or charge through a resistor. In either case, there is no charge limit whatsoever. I suppose it's ok if the charge current is really really small, but not the best IMO.

To charge the batteries in all my household items (remotes, cameras, etc), I took a radio shack charger, gutted it, and added terminals to hook to my "real" chargers. What's nice about this is I can charge 1 to 4 AA's or AAA's, or a 9v battery in one package.

[JERRY2KONE]

If I were you DABID I would just build the pack and slide it into use for your camera without telling your Dad and let him see how much better your setup will operate compared to the original pack. Some people are just afraid to step outside of the box, because they fear change and failure. Sometimes you just have to take matters into your own hands. Go for it, and good luck with your project.

[DrKnow65]

Jerry2Kone & Dabid, this might upset dad, I wouldn't go this route.

I would get a piece of Scotch tape (the "invisible" stuff you use for christmas wrapping) and put a small piece of it on one of the wall charger (battery) terminals. This will keep it from making contact and charging the battery.

When Dad wants the camera to work he might just reconsider your offer to charge it the better way :)

Sometimes it's just easier to ask for forgivness than it is to ask for permission.