Panasonic AAA Ni-MH question

Guys, I just bought some Panasonic cordless phones and they came with panasonic brand Ni-MH AAA's rated at 630mAh.

Now, the screens are very big and bright and I don't get the same talk time out of them as my older phones with smaller and not so bright screens.

I assume that going to a more powerful battery would improve things but my questions are:

If I go from 630 to 1000mAh, will I get almost double the talk time or not?

How are these numbers usually? Over or underrated or what?

What's the most powerful AAA and is it worth the money or should I go for a lesser battery at lower cost. Ie, compare these two..
http://www.batteryjunction.com/onepcsofaaa1.html 89 cents each
http://www.batteryjunction.com/ges-nh1000-bp.html 3 bucks each

Finally, how about my Eneloops which seem to be 800mAh?

Thanks

George

AAA NiMH's are my second most used cells. That is to say I have far less experience with AAA's than AA's. That said, I've used a number of different brands, some good like Sanyo 900 and 1000mAh, and some lesser brand/generic types.

From the experience that I have had, I'd be willing to bet that the eneloop AAA's will out perfrom any of the "standard" NiMH cells after the first year of use (very possibly sooner). From what I've seen here on CPF and elsewhere, they'd probably out perform the other LSD NiMH cells as well.

While LSD cells are not necessarily best for use in something like a cordless phone that gets charged and discharged frequently, that's still what I'd go with if I was in your situation.

Hey, now that Panasonic has bought out Sanyo's battery division, you'd stll be using OEM cells,.....well sorta!

Dave

So, eneloops then?

What's LSD? (Not the drug, right)

guiri said:

What's LSD? (Not the drug, right)

Click to expand...

Ha! No, LSD=Low Self Discharge.

Yeah, I'd use the eneloop AAA's.

Dave

Thanks

45/70 said:

While LSD cells are not necessarily best for use in something like a cordless phone that gets charged and discharged frequently, that's still what I'd go with if I was in your situation.

Dave

Click to expand...

Use it til it dies and then charge?

Most cordless phones cut out at about 1.2 Volt/cell so, yes, that'd be OK. Of course NiMH cells can be charged most anytime you want, provided you do run them down every couple months or so.

Dave

Alright, I don't really understand. Eneloops are Ni-mH or what? Run them dry every time?

The phones not in use, should I keep them on the chargers all the time?
Let the batteries die and only charge when I need them, or
Keep rotating them all so that they all get SOME use?

Hello guiri.

"To prevent potential irreparable harm to a battery due to polarity reversal of one or more cells during
discharge, the load (discharge current) must be terminated prior to the battery being completely discharged.

Continuing the discharge to lower end
voltages can slightly increase the delivered capacity, yet if the end voltage is set below the
recommended Voltage Cutoff the cycle life of the battery will be decreased."

It is not a good advise to drain NiMh completely, ever.
If you dont know at what voltage the phone cutoff you cant use it til it dies.

Anders

guiri, Anders is correct about it being bad for a NiMH cell to be discharged to zero Volt. Under load, a NiMH cell typically shouldn't be discharged to a voltage lower than ~0.8-0.9 Volt, or discharged to a level where after resting a bit, the open circuit voltage (OC) of the cell reads less than ~1.20 Volt.

It is my experience with cordless phones however, that they usually start warning of a low battery condition at some point above 1.2 Volt/cell OC, and stop working completely at around 1.2 Volt/cell OC. I have a Panasonic KX-TGA2438 handset here for example, that the display goes blank and all functions quit once the pack (2x5/4 AAA) voltage reaches 2.4 Volts OC. This translates to 1.2 Volt per cell (2.4/2=1.2) and is quite an acceptable discharged voltage for NiMH cells.

I don't usually let the phone discharge until it quits, as I need to know that it will work, and need to use it. I do however try to let it discharge until it quits, once every month or two. This prevents any memory effect, helps balance the chemical distribution within the cells, and prolongs the overall life of the pack.

Your phones may be different. I'd hazard a guess that they work similarly though. It wouldn't hurt to check the voltage of the cells to see at just what voltage they do quit working. If the cells are at ~1.20 Volts when the phones quit, you're good to go.

Dave

Keep in mind that the actual capactiy of an eneloop is less than regular NiMH but I think 45/70 suggested them not because their mAh, but for their toughness and slighty higher voltage.

In reference to vali's post above, yes, and as I alluded to in post #2, after a year (or less) the eneloops probably will have a higher capacity than 900 or 1000mAh standard AAA cells.

And to clear a couple points up,

guiri said:

The phones not in use, should I keep them on the chargers all the time?

Click to expand...

No, I wouldn't do that. eneloops, and all NiMH cells for that matter, don't like to be trickle charged constantly. It's better to just have the handset on the charging cradle when you are actually charging the phone. Once charged, leave it off until you want/need to charge it.

I think a lot of cordless phone manufacturers make a lot of extra $ by stating that you can "leave the phone on the charging cradle when not in use". They sell a lot more replacement battery packs using this recommendation. I learned about this the hard way. My phones that I left on the charging cradle when not in use had an average battery pack life of about one year (oddly enough, that's what the phone manuals also speculated). After learning that constant trickle charging NiMH cells was not good for them, I started not leaving the phones on the charging cradle when not in use, except for charging. My battery packs now last 3-5 years.

Keep rotating them all so that they all get SOME use?

Click to expand...

That's not a bad idea, since you are using individual cells, rather than battery packs.

Dave

45/70 (as in the caliber?)

I'm sure my panasonics are just like yours and I DO charge them when they start warning (at least these new ones, the older ones got to the point that they just died on me) and yes, for the same reason. I need one working not one that just dies on me.

What about the other phones (I got 6 handsets), should they be on the chargers all the time or should I alternate and use them or what?

Oops, I see you answered this. HEre's the thing, if I don't charge them and keep them on the chargers, should I simply take the batteries out, charge them and put them away then? Otherwise the phones will completely discharge them if they're inside the phones, right?

THanks again guys

guiri, cells or packs that I'm not using, I try to store not fully charged or fully discharged. It doesn't always work out that way, but fully charged is probably better than fully discharged, as it insures the voltage doesn't drop too low.

Yes "45/70" is in reference to the rifle caliber. I am a gun collector, and my specialty is straight stocked lever action repeating rifles (but including single shot Winchester High Wall and Sharps falling block levers, as well) of the old American West.

The 45/70 is probably my favorite caliber of these arms, in part because it has been in use for over 135 years, and can still hold it's own reasonably well today, particularly with smokeless powder handloads. Any shop that carries a reasonable selection of rifle ammunition will likely have 45/70 in stock, although, as I said, I pretty much handload exclusively. My favorite rifles in this group are the Winchester models 1886 and 1885, Marlin Model 1895, and the Model 1874 Sharps.

I use "45/70" rather than "45-70" because originally, it meant a .45 caliber bullet over (/) 70 grains of FFg or FFFg black powder. When the 30-03 Springfield (.30 caliber introduced in 1903) came out, and later the 30-06 and other "modern" cartridges, a lot of the old designations changed over to the newer format, although not actually correct for the older black powder cartridges.

OK totally OT!

Dave

I use 2xAAA eneloops in a cordless phone.

For charging, I remove the batteries, replace with fresh eneloops, and charge the used cells myself (Maha C9000).
I never actually put the phone on the charger/base station.

That way the batts are charged properly, and the phone is always ready to go.

Niconical, the problem is I'm too damn lazy to do that AND, I think when you take out the batteries, you then have to register the handset with the base unit every time..

Dave, so you are saying I should discharge batteries PARTIALLY before storing? Why?

Hey, got any pics of your guns?

I just traded a printer for an AK myself

Gearing up for the SHTF scenario. That or the zombie invasion

I've even looked at this cool .50BMG that's only 14 lbs total IF I ever get the money.

I just bought a set of these Panasonic cordless phones, the chargers are smart chargers, they will shut off when the batteries are charged. You should see the charge light turn off and the display will say charged when its complete. So there won't be any worry about the usual over charging due to truckle chargers.
I have a MAHA c9000 charger and number all my batteries and will run them through a refresh every 6 months to a year depending on if they are heavily or lightly used (batteries 1-8 stay with the digicam for example and are heavily used while 9-16 may be for the scanner which is lightly used to every year) and record the capacity so I can determine if they are still performing good. I can do the same with the phone batteries now too.

Holy crap that's ambitious.

Thanks Eugene

you will find that quite normal in this forum. People with a lot of batteries will number or otherwise ID them in some way to keep track of them, after you get a couple dozen batteries you have to keep track of them in some way. Then couple with the higher end chargers like the c9000 haveing the refresh and break in cycles letting you test the capacity you can be sure the batteries in your digicam are still going to work.

I would imagine that LSD cells would actually not be prefered in this situation? Given that the cordless is used on a regular or frequent basis, capacity should be more important...