Lifespan of Recharge NiMH Battery 4.8v 550ah???

[vern007]

I bought a couple pair of bubble pack RS walkie talkies to monitor a disabled family member in another room 24/7. I keep one pair in the charger while the other is in use. With a 16 hour charge I am presently getting about a 24 hr battery cycle. Based on the specs posted in the subject header, does anybody know how long this battery pack will last (NIMH /4.8v 550ah)? And will it lose its charge incrementally? Any help is appreciated. I noticed in the radio shack instructions it recommends depleting the charge fully to extend the battery life, whereas the same brand that Uniden sells--their directions do not mention that. There is always a small charge left for scanning at the end of a cycle, but not for transmitting, and I do try to deplete that charge, but it becomes annoying. Any thoughts on completely depleting the charge before recharging, beyond the flashing "battery is low" indicator?

 

[n2mdk]

You never want to "fully" deplete NiMH batteries it's OK to let them go down till the low batt comes on or even allow the radios to shut off. That's fine. Overcharging batteries isn't a good idea either but it's doubtful that leaving them on charge will hurt, people do that with cordless phones all the time. When the useful battery life goes down you will know at that point get replacements, packs are cheap enough, especially aftermarket ones.

 

[N_Jay]

A NIMH battery will usually take 300 to 500 charge/discharge cycles before it loses 20% of its capacity.
The same battery that is never charged over 85% to 90% (Before heating occurs), and is never discharged below 10% (About 1 volt per cell), will last several thousand cycles.

Yes, degradation is sow, except if a cell fails due to reverse charging" which occurs when you use a battery pack beyond its intended capacity (over discharge).

 

[vern007]

thanks very much!

It's interesting how we live in a disposable culture. I did an internet search looking for a replacement battery pack for my particular RS walkie talkie just so I know where to go in the future. The battery pack (BP-40) is essentially 4 AAA NIMH batteries wrapped in black plastic with a couple of flat contacts in the front. Funny, radio shack does not sell them. Uniden sells them for 20 a pop and only one other online retailer online also sells them for about 15 a pop. You would think there would be more demand since RS sells quite a few of these gadgets.

http://www.123radios.com/BuyNow.asp?CID=63 http://www.unidendirect.com/accdetail.cfm?item=BP40

 

[vern007]

Interesting incident the other night. Had to pull a pair of WT's out of the charger prematurely because they were needed. So, instead of a 16 hr charge, they received only 13 and a half. Yet, when I used them till completion, I got the same 22 hr charge that I had been getting when charging them for 16hrs. These batteries are about 6 months old and have been in constant use from day one. So, this is good. Just wondered, is there a term for this, some weird memory effect? Could I get away with this again?

 

[bee]

"30 a pop"? "20 a pop"! What is a "pop"

 

[slicerwizard]

Dang - a 550 amp hour battery pack for a portable radio. It should need charging about once a year...

 

[Don_Burke]

Dang - a 550 amp hour battery pack for a portable radio. It should need charging about once a year...

Does it come with the wheels or do you have to get them aftermarket?

 

[Don_Burke]

"30 a pop"? "20 a pop"! What is a "pop"

That would be "each."

 

[LEH]

thanks very much!

It's interesting how we live in a disposable culture. I did an internet search looking for a replacement battery pack for my particular RS walkie talkie just so I know where to go in the future. The battery pack (BP-40) is essentially 4 AAA NIMH batteries wrapped in black plastic with a couple of flat contacts in the front. Funny, radio shack does not sell them. Uniden sells them for 20 a pop and only one other online retailer online also sells them for about 15 a pop. You would think there would be more demand since RS sells quite a few of these gadgets.

http://www.123radios.com/BuyNow.asp?CID=63 http://www.unidendirect.com/accdetail.cfm?item=BP40

RS does sell replacement rechargeables (not sure if they are NiCad or NiMH now) with solder points on them for battery packs like that. I've bought some plastic electrical tape and replaced my own on more than one occasion. Cheaper than the replacement pack.

Just open up the old pack, desolder the wire and connector (otherwise you may wind up with length issues), make a GOOD NOTE of the arrangement of the current battery positioning, solder the new batteries in that order, attach the wire with connector, apply tape and replace the battery pack.