Another Battery question

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EJB

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I own a Bcd396t and use two sets of batteries, 2500 Engergizers & 2650 Duracells.

Using a GP charger, nothing fancy, after a 12-15 hr charge I normally got about 8-10 hrs on the 2 year old Energizers & 10-12 on the 8 month old Duracells, monitoring analog trunked systems & P25/Analog systems.

In my car I have to increase the volume a fair bit to hear, in my house it is generally at around 3 or 4.

Lately I have noticed that both sets of cells do not keep a charge in the 'high' zone (3.8 & up) for very long and the use time in both dropped by 50-65%.

I bought a new charger, an Energizer slow charge unit at Best Buy.

The Energizer batteries lasted about 6-8 hrs, mostly at hugh volume monitoring P25 systems.

The Duracells were different. I had it going well, albeit the numerical value dropped quickly from 4.22 to 3.67 (approx) very quickly.
After about 4 hrs of use the battery indicator lite came on.
I proceeded to try to discharge the batteries, i.e. keep it on but while the lite flashed the scanner scanned away, for another 2 hrs
I went to turn it on again this AM and the power level increased back up to 3.6m no battery indicator lite on.

My question:
Did I F up my batteries using my old charger or is there perhaps something wrong now with my radio?

Thanks in advance.

edit- I should add I had the backlight switched to squelch using the energizers & keypad push for the duracells.
Eric
 

DPD1

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Most of the chargers they sell at regular stores aren't as smart as they claim to be. Most are set to charge the batteries that come with the charger. If you try using different batteries, it may over or under charge them. Over charging is especially harmful and will decrease the life. Most chargers also charge very fast because they know people are impatient, which is also bad for the batteries. Also, it doesn't hurt them that the batteries won't have as long a life as they should, since they know you'll just spend money on new ones. I doubt there's something wrong with the radio. No matter what you do, the batteries will go bad at some point. The only way you can really see what's going on is to get a charger that allows you to see how much they're holding and all that. Then you can set it to recondition, discharge, or charge accordingly. Otherwise you're just guessing.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist
 

EJB

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Thank You Dave.

I have seen threads about good chargers;

I knew enough not to buy a 15 min charger. To me those would kill the batteries faster.
 

slicerwizard

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Santa left me an Energizer 15 minute charger this year (I didn't ask for it - it was her idea), along with some new AA and AAA NiMH cells. So far, it's been great - I made a car lighter socket cable for it, so whenever my 246, 396, GPS, camera, MP3 player or FM transmitter die, I just pop the cells in the charger for a few minutes. Two minutes in the charger is enough to run a scanner for more than an hour, so I don't even have to wait the full 15 minutes (although I usually do)

I would've preferred a smart charger (like Maha, LaCrosse, etc.), but this charger is also well built with lots of electronics in it. The cells don't get hot and a web search turns up far more satisfied customers than unhappy campers, so I'm giving it a thumbs up for now. With a fast charger, the cells actually live a relatively easy life, since there is no need to run them down and recharge them every night. We'll see how they fare over the long term.

As for your concerns, it looks like some of your cells are getting old. Their internal resistance has gone up - hence the lower terminal voltage. NiMH cells just don't last as long as the NiCads they replaced and yes, your old charger probably helped do them in.
 

unitcharlie

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I posted part of this in another thread... last summer a bunch of Duracell 2650 mAh AA batteires died on me suddenly and I called Duracell to see what was going on.... the customer service lady explained that the Duracell Power Gauge Charger (Model CEF21N) would bring them back to life... long story short--although it didn't revive the bad batteries, it brought a number of Duracell NiMH batteries I hadn't recycled back to life and saved me a bunch of bucks. The thing isn't fancy, your basic black box with four ports that accept AA or AAA batteries, three red lights that show charging progress and a green light when thay are finished (you can also use it to charge USB devices when the ports aren't charging AAs or AAAs). Have been using it since late summer 2007 and have had no battery problems since then.... except for the three GP 2300mAh batteries that came with the 396, all I use are Duracell NiMH.... two sets of three 2300mAh to rotate around the 396 and five sets of 2650 mAh that rotate through my various scanners.... you'll have to search for this charger because it is not as easy to find as their 15 minute charger.... I found mine on the Office Depot web site for about 25 bucks...

I use my Maha 204 for the other batteries, but the Duracells only charge in the Power Guage...

collier
 

EJB

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slicerwizard said:
Santa left me an Energizer 15 minute charger this year (I didn't ask for it - it was her idea), along with some new AA and AAA NiMH cells. So far, it's been great - I made a car lighter socket cable for it, so whenever my 246, 396, GPS, camera, MP3 player or FM transmitter die, I just pop the cells in the charger for a few minutes. Two minutes in the charger is enough to run a scanner for more than an hour, so I don't even have to wait the full 15 minutes (although I usually do)

I would've preferred a smart charger (like Maha, LaCrosse, etc.), but this charger is also well built with lots of electronics in it. The cells don't get hot and a web search turns up far more satisfied customers than unhappy campers, so I'm giving it a thumbs up for now. With a fast charger, the cells actually live a relatively easy life, since there is no need to run them down and recharge them every night. We'll see how they fare over the long term.

As for your concerns, it looks like some of your cells are getting old. Their internal resistance has gone up - hence the lower terminal voltage. NiMH cells just don't last as long as the NiCads they replaced and yes, your old charger probably helped do them in.




Thank You Andrew. I will probably now invest in a set of new batteries.
I ended up getting 10 hrs on my 'damaged' 2650,' using my new charger.
The damage is that normally the cells held their charge in the 3.7 & 3.8 area for hours, these batteries dropped off quickly from their peak to 3.6 then 3.5 and into low battery indicator. I did find that the low battery indicator light did not return after I shut the unit off and I was able to get another 5 hrs of use.
Is there anywhere else where I can get ones that are '2650' & up in the GTA besides the usual suspects? Hobby stores?
Pharma plus do sell duracells.
 

slicerwizard

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EJB said:
The damage is that normally the cells held their charge in the 3.7 & 3.8 area for hours, these batteries dropped off quickly from their peak to 3.6 then 3.5 and into low battery indicator. I did find that the low battery indicator light did not return after I shut the unit off and I was able to get another 5 hrs of use.
That's odd behaviour - after the low battery warning starts, you can turn it off and back on and get five more hours of beep-free runtime? I'd try cleaning the battery ends and the contacts in the scanner, although I doubt that's the problem. If it was my scanner, I'd be checking the voltage of each cell while the scanner was running off them, e.g. leave the battery cover off and check each cell with a voltmeter while they're under load. Maybe one of them is acting up.

Is there anywhere else where I can get ones that are '2650' & up in the GTA besides the usual suspects? Hobby stores?
I have no idea. Santa got my 2650's at WallyWorld and they're doing a great job in the 396.
 

N1BHH

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The low battery indicator is more likely from current drain, not voltage drop. A 2500 mAH battery could drain to maybe 500mA and still run a radio, but a radio's low battery circuit may be looking for at least 750mA to allow the radio to operate. Voltages don't usually drop very much to set off low life indicators in some radios, it's the current which most likely causes this.

Read this article, it's really in depth on NIMH batteries:
http://en.wikipedia.org/wiki/Nickel-metal_hydride_battery
 

EJB

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Thanks for all the input guys.

I will probably go get a pair of 2650's shortly.

My energizers probably got about 5-7 hrs on my last run, however I did not tun them down to 'zero' this time.
I find that they are more flakey than the duracells, one of the 4 pack that I got is def a dud.
 

slicerwizard

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N1BHH said:
The low battery indicator is more likely from current drain, not voltage drop. A 2500 mAH battery could drain to maybe 500mA and still run a radio, but a radio's low battery circuit may be looking for at least 750mA to allow the radio to operate. Voltages don't usually drop very much to set off low life indicators in some radios, it's the current which most likely causes this.
And how exactly do you look for "750mA"? Where will you find it? In the batteries? How would you measure it? You certainly won't find 750mA flowing anywhere in a 396T. Your statement makes no sense to me.

The 396T uses the typical analog to digital converter arrangement to measure the total battery voltage and the scanner starts complaining when it drops below 3.5V. It will auto power down when the voltage gets below 3.4V; no mA in there anywhere.
 

EJB

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Follow up

Andrew:
I broke the bank & bought a new set of Duracells 2650's. Walmart 12.99.

I just charged them up overnight & threw three im.
On my older 2650's they would begin at about 4.21. These began at 4.35!.

My conclusions: My old charger ruined my other batteries (I got about 4-6 hrs, many with the battery indicator on with the light on) & they are gonna go to the great recycling bin in the sky.

Now I am gonna see how long they hold a charge.
Off to the city to watch the game. Will have it on for maybe 4-6 hrs over the next 24.

Eric

P.s where is my pm about the secret chat room :)
 

KR4BD

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I have been using some 2900 mah NIMH batteries for nearly a year now. I got them from a vendor at the Dayton Hamvention last May who was selling them for $20 per DOZEN. The brand name is POWER2000. I charge them in an external wall mount charger for about 8 hours and get about 20 hours of use per charge in my Pro-94 and Pro-97 scanners. I have not seen these batteries offered elsewhere, but have seen them offered on the internet. Just Google "Power2000 AA Batteries". I understand that some photography stores sell them. These last noticeably longer than the 2500 mah Energizers I also have.
 
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