600 mAh vs. 700 mAh

[rock]

My AT&T cordless phones take 3.6V 600 mAh batteries. The replacements can only be found online or in specialty stores for $8-10.

But, I found 3.6V 700 mAh replacements with the same plug at Lowes for like $5. I used this a few months ago and the battery didn't last very long at all, and now I need another one.

What's the difference? I'd kind of expect the 700 mAh to last longer, what with more "milli Amp hours" to give and the same current load. Is it worth the hassle to order a 600 and pay shipping over just going down to Lowes and getting another 700?

[ua549]

Make sure the 700mAh battery is a specified replacement. If so, buy it. I say to make sure because there are some cheap and/or counterfeit batteries that have exploded in Nokia handsets.

[masteraleph]

Originally posted by ua549
Make sure the 700mAh battery is a specified replacement. If so, buy it. I say to make sure because there are some cheap and/or counterfeit batteries that have exploded in Nokia handsets.

Also, in terms of how many times you can recharge it, the mAh makes no difference. The only reason you'd need a higher mAh is if you need the cordless phones to spend more time out of the charger. But a cheap mAh may have memory issues and not allow you to recharge it as many times.

[rock]

Originally posted by masteraleph
Also, in terms of how many times you can recharge it, the mAh makes no difference. The only reason you'd need a higher mAh is if you need the cordless phones to spend more time out of the charger. But a cheap mAh may have memory issues and not allow you to recharge it as many times.

I think that's what I ran into here - a cheap replacement. I'll have to shop around for a decent replacement this time.

[Moridin]

Originally posted by rock
My AT&T cordless phones take 3.6V 600 mAh batteries. The replacements can only be found online or in specialty stores for $8-10.

But, I found 3.6V 700 mAh replacements with the same plug at Lowes for like $5. I used this a few months ago and the battery didn't last very long at all, and now I need another one.

What's the difference? I'd kind of expect the 700 mAh to last longer, what with more "milli Amp hours" to give and the same current load. Is it worth the hassle to order a 600 and pay shipping over just going down to Lowes and getting another 700?

The cheep batteries probably do not perform as well under load.

As current increases V drops, so they may supply 3.6 V with no load attached but under the load of your cell phone they likely provide less then 3.6 V


They also are likely to have poor V vs t characteristics.
Any batteries V output drops as it discharges. What you want is a relatively constant V, that drops suddenly when the 700mAh is reached, what the cheep battery likly provides is V that drops steadily over time.

Combine these two and you end up with a batteries that only supplies sufficient V to operate your phone for the first 350 mAh. The other 350 mAh is still there, but only at a voltage insufficient to run your phone properly

At least thats my guess. Whether the good batteries are "worth it" is up to you.

[russ_watters]

The biggest issue I would see here is making sure the battery type is the same (NiMH, NiCd, etc). If it is, the only difference you would notice is it lasting 1/6 longer on a charge. If it is not, you could destroy the batteries, destroy the phone, start a fire, etc.

[rock]

So I skipped the cheap batteries this time and got an AT&T. The problem is, they've moved to the 2.4ghz phones, while this one is a 900mhz. And the new phones take 1300mAh 3.6V batteries. So, I got one anyway, figuring it'll be okay for the wife to leave it off the charger for ever....

Will let you know if it catches fire.