396 batteries

[emt331000]

I agree that letting them sit is wasting valuable electrons, but I think you might find some problems with your other calculations.

First, voltage and remaining charge are not linear - especially in NiCd and NiMH cells which have a bit of a peak at full-charge, stay fairly flat over most of their discharge and have a sharp dropoff at the end.

Second, the literature suggests a large initial loss (pretty close to your estimate) of around 10% in the first day but then perhaps 1%/day afterward.

That's fine. But, I never intended for my results to dictate the entire charge life of the batteries, only the charge that is necessary to power the scanner -- and only to represent the days rest from charging that yaesumofo gives them. The rest does not matter. So, no -- there are no problems with my calculations. They were entened to represent the first 24 hours only.

When the 396 repeatedly shuts down at approximately 3.623 volts remaining, what do those two things matter? It doesn't matter if the discharge remains "fairly flat" at 1% per day for the remainder, because they still don't have enough charge to run the scanner.

At nearly 11% loss in the first 24 hours (which is slightly less than I found), only 3.66057 volts remain. The scanner shuts down at 3.623...

(BTW, the total volt reading after full charge should have been 1.371 each, not 1.361. But, this has little affect on the results.)

 

[linuxwrangler]

I'm only noting that voltage does correlate linearly with charge level.

Your shutdown results are interesting. Are you measuring voltage with an external voltmeter or using the scanner's built-in voltmeter? I have never tried to verify the internal meter readings with my Fluke but I do know that when fully charged NiMH are put into my 396, its battery meter reads about 4.20 and the low-battery beep on my 396 starts when the scanner's battery meter drops to 3.50. If I can't replace the batteries, I have about 1-hour remaining (based on the batteries I use) before the scanner dies which happens IIRC at 3.45 on the battery meter.

 

[emt331000]

I'm only noting that voltage does correlate linearly with charge level.

Your shutdown results are interesting. Are you measuring voltage with an external voltmeter or using the scanner's built-in voltmeter?

As I said in my original post, " I tested each set two times with a multimeter."

I have never tried to verify the internal meter readings with my Fluke but I do know that when fully charged NiMH are put into my 396, its battery meter reads about 4.20 and the low-battery beep on my 396 starts when the scanner's battery meter drops to 3.50. If I can't replace the batteries, I have about 1-hour remaining (based on the batteries I use) before the scanner dies which happens IIRC at 3.45 on the battery meter.

My 396 shows the same thing. But again, I trust a dedicated multimeter more than the makeshift voltmeter of this scanner. I don't think Uniden intended theirs to be a precise measuring tool. After all, they didn't even mention it in the user manual!

 

[MarkWestin]

Just remember that your "dedicated voltmeter" does not measure your battery under load while the scanner's "battery meter" does. I believe that at least part of what you are measuring with your voltmeter is referred to as "surface charge".

Mark

 

[emt331000]

Just remember that your "dedicated voltmeter" does not measure your battery under load while the scanner's "battery meter" does. I believe that at least part of what you are measuring with your voltmeter is referred to as "surface charge".

Mark

Maybe, maybe not. My multimeter returned a reading similar to the 396 when the batteries were fully charged; the difference comes later on, which suggests the 396 isn't accurate. I stand behind my conviction that a dedicated multimeter is more reliable than the 396's makeshift volt meter. Is anyone suggesting otherwise?

Regardless, what is important is that the batteries need only lose some 0.49 volts for the scanner to be rendered useless, and they lose a substantial amount of their total charge in the first 24 hours.

Battery life for the 396 isn't long. That's what's important.

 

[capnron]

Agreed

I have noticed that almost 100% of the time when handhelds start showing reduced run time that if I check all of the cells individually with a good digital voltmeter, just 1 battery is causing it. I check them as soon as the low battery warning starts. If one of them is much lower than the others, I chuck it out and replace it with another of the same brand & capacity as the rest.
I guess NiMh batteries don't go bad at the same time even if they were born at the same time.

That is exactly what I've noticed Thayne. If I start getting short runs from a specific group its always 1 bad battery. I've had a lot of bad energizers but my GP 2700's rock. 13.5 hours per charge. As well, I have a very good charger which helps. (AccuPower 2020-1)

 

[AZMONITOR]

Batteries & Charger For BCD396

I use the Powerex 2500 mah batteries along with a Maha MH-C801D charger and reconditioner which can charge AA or AAA batteries in any number from one to eight.
Usually I get between 10 and 11 hours of usage on one charge with the 396. As a result I am most happy with the batteries and charger.

 

[linuxwrangler]

The results are in and I'm a bit surprised. I tested capacity 0, 24 and 48 hours after removing from charger and saw the following:
0h: 2210mAh
24h: 2160mAh (-2.3%)
48h: 2106mAh (-4.7%)

Far less self-discharge than the oft-reported 10% in the first day. I used the discharge mode set to 200mA (close to 396 draw) on my MH-9000 to do the capacity tests. Results are the averages of three tests each on each of a matched set of three cells.

The MH-9000 uses the IEC standard testing method and I had previously determined that the 396 dies with about 15% charge remaining based on IEC values. Adjusting for this, I calculated that the "396 usable capacity" drops 2.7% after 24 hours and 5.6% after 48.

The cells had undergone a break-in conditioning cycle before the tests started and to cancel effects of additional conditioning I ran the tests in different orders (ie 0h 24h 48h, 48h 0h 24h...). Each cell was run through a 0, 24 and 48 hour test and each was fully charged and topped off before starting the test. I don't know the real manufacturer but the cells were sold under the "Ultra Pro" brand and I bought them at Fry's.

If I were a "real scientist", I'd have to add that the sample size is too small and further funding is needed to run additional tests and confirm results. But it does suggest that the first-day self-discharge is far lower than frequently reported. It makes me wonder if the 10% figure is one that has persisted from the early days of MiMH and that modern NiMH manufacturing techniques have considerably reduced the self-discharge issue.

 

[slicerwizard]

A nearly 0.1 volt loss each per day is substantial -- nearly 12% of their charge!

Your conclusion has no basis in fact. As others have pointed out, proper testing shows that far less than 12% of the initial charge is lost in 24 hours.

 

[slicerwizard]

Maybe, maybe not. My multimeter returned a reading similar to the 396 when the batteries were fully charged; the difference comes later on, which suggests the 396 isn't accurate. I stand behind my conviction that a dedicated multimeter is more reliable than the 396's makeshift volt meter. Is anyone suggesting otherwise?

Of course we are. You're comparing the 396's measurement of cells under load against your fancy meter's useless no-load measurement and you don't even realize why they're different. And then you blame the 396! If the under load and no load readings were the same, then you should be raising a stink.

If you want to compare the two devices, measure the battery voltage with your fancy meter while the cells are powering the scanner. Just take the battery cover off and do it already.

Regardless, what is important is that the batteries need only lose some 0.49 volts for the scanner to be rendered useless,

Hm. That's about what three cells lose from 100% charge to about 5%. Takes mine about ten hours in my 396 to do that.

and they lose a substantial amount of their total charge in the first 24 hours.

That just isn't true - unless your cells are defective or ruined, which has yet to be determined.

Battery life for the 396 isn't long. That's what's important.

Ten hours for me. You need to figure out if the problem is with your cells or your scanner. So far, you haven't done that. Big hint: use your meter to measure the individual cell voltages while under load when the low battery alert starts.

 

[emt331000]

Your conclusion has no basis in fact. As others have pointed out, proper testing shows that far less than 12% of the initial charge is lost in 24 hours.

You're saying that testing them with a multimeter once they've sat on a desk for 24 hours after doing a complete charge with a Maha MH-C9000 charger isn't proper to see how much of their charge is lost in a 24-hour period? I beg to differ. Who are these "others" that you speak have "shown far less than 12%"? What method did they use? What method do you think is proper?

You say "of course we are" saying that the 396's makeshift volt meter is more reliable than a multimeter. Now I'm convinced you don't know what you are talking about. Do you think the 396's signal meter is highly reliable, too...? What about its charger...?

Ten hours for me.

Ten hours of doing what, exactly? Different use will produce different charge life.

You need to figure out if the problem is with your cells or your scanner.

OK. I just purchased several more sets. ALL have the SAME result. Are all of these batteries bad, too...?

Big hint: use your meter to measure the individual cell voltages while under load when the low battery alert starts.

It is impossible to fit multimeter probes into the battery compartment of the scanner to test the batteries while they are inserted in the scanner and powering it. Uniden did not leave enough room for them. Even if they did, the probes would push the battery connectors away from the battery, turning off the scanner.

But, none of this matters because what you want has absolutely no bearing on what their output is after sitting on a desk for 24 hours. 2500 mah ni-mh batteries loose 11-12% of their charge when resting, whether they are inside the scanner or not.

Nitpick all you want, slicerwizard. I stand behind my findings. 2500 mah batteries lose approximately 11-12% of their charge within the first 24 hours when they aren't being used -- period! BTW, what test resuls have you published...?

 

[emt331000]

The results are in and I'm a bit surprised. I tested capacity 0, 24 and 48 hours after removing from charger and saw the following:
0h: 2210mAh
24h: 2160mAh (-2.3%)
48h: 2106mAh (-4.7%)

Far less self-discharge than the oft-reported 10% in the first day. I used the discharge mode set to 200mA (close to 396 draw) on my MH-9000 to do the capacity tests. Results are the averages of three tests each on each of a matched set of three cells.

The problem with this is that the charger won't let the batteries drop less than how you've set it. The other problem is that you ran the discharge for more than 24 hours, trying to duplicate the load of the 396. Yet, the batteries will never last for 24 hours when being in constant use by the scanner, as I'm sure everyone will agree.

All I did with my test is to simply test their voltage after a full 24 hour rest after they were fully charged. All forty-eight 2500 mah AA's that I own lose approximately 12% of their charge.

 

[emt331000]

Hm. That's about what three cells lose from 100% charge to about 5%. Takes mine about ten hours in my 396 to do that.

Three AA ni-mh batteries have some 4.11 volts at 100% charge. To reach the 5% charge you speak of, they'd only have 0.2055 volts combined remaining (5% of 4.11). What voltage reading does your 396 display just before it shuts off? I'm sure it isn't 0.2055, as it must be for your words to be correct. The 396 cannot bring the batteries that low.

 

[slicerwizard]

Three AA ni-mh batteries have some 4.11 volts at 100% charge. To reach the 5% charge you speak of, they'd only have 0.2055 volts combined remaining (5% of 4.11). What voltage reading does your 396 display just before it shuts off? I'm sure it isn't 0.2055, as it must be for your words to be correct. The 396 cannot bring the batteries that low.

I'm just going to be blunt here - pretty much everything you've said is wrong and it looks like you'll never be convinced otherwise. I just wish you wouldn't push your strange ideas on others who might not know better. You think that a cell with 5% charge remaining will have a (loaded) voltage of less than a tenth of a volt? That's preposterous, but you believe it!

You also think that no load voltage measurements are meaningful. Tell me, how do they show a cell's internal resistance? Do you have any idea how much current your meter draws from a cell? Do you have any idea why it's relevant? Didn't think so.

You're saying that testing them with a multimeter once they've sat on a desk for 24 hours after doing a complete charge with a Maha MH-C9000 charger isn't proper to see how much of their charge is lost in a 24-hour period?

Hello? THAT'S NOT A TEST.

I beg to differ. Who are these "others" that you speak have "shown far less than 12%"? What method did they use? What method do you think is proper?

A real capacity test. What did you think the "mAh" in the results meant?

You say "of course we are" saying that the 396's makeshift volt meter is more reliable than a multimeter. Now I'm convinced you don't know what you are talking about. Do you think the 396's signal meter is highly reliable, too...? What about its charger...?

The 396's loaded voltage reading is far more meaningful than your meter's unloaded reading. Will you ever understand that?

Ten hours of doing what, exactly? Different use will produce different charge life.

Ho hum. Monitoring a busy SmartZone system.

It is impossible to fit multimeter probes into the battery compartment of the scanner to test the batteries while they are inserted in the scanner and powering it. Uniden did not leave enough room for them. Even if they did, the probes would push the battery connectors away from the battery, turning off the scanner.

And it's impossible for you to figure a way around this? You can't come up with some small jumper leads or tin foil strips? Are you really this helpless?

But, none of this matters because what you want has absolutely no bearing on what their output is after sitting on a desk for 24 hours. 2500 mah ni-mh batteries loose 11-12% of their charge when resting, whether they are inside the scanner or not.

Yeah, just keep repeating that "unloaded voltage equals charge level" nonsense.

Nitpick all you want, slicerwizard. I stand behind my findings. 2500 mah batteries lose approximately 11-12% of their charge within the first 24 hours when they aren't being used -- period! BTW, what test resuls have you published...?

That's funny, considering you haven't done any testing. I guess you think garages test car batteries by just sticking a voltmeter on them. I might as well be talking to a brick wall...

 

[emt331000]

I'm just going to be blunt here - pretty much everything you've said is wrong and it looks like you'll never be convinced otherwise. I just wish you wouldn't push your strange ideas on others who might not know better. You think that a cell with 5% charge remaining will have a (loaded) voltage of less than a tenth of a volt? That's preposterous, but you believe it!

Hello? THAT'S NOT A TEST.

The 396's loaded voltage reading is far more meaningful than your meter's unloaded reading. Will you ever understand that?

And it's impossible for you to figure a way around this? You can't come up with some small jumper leads or tin foil strips? Are you really this helpless?

Yeah, just keep repeating that "unloaded voltage equals charge level" nonsense.

That's funny, considering you haven't done any testing. I guess you think garages test car batteries by just sticking a voltmeter on them. I might as well be talking to a brick wall...

If you say so...After all, you are a self-proclaimed "wizard," and you see insulting people as the best way to instruct them. So, have at it...! How's that working for you...? :roll:

But before you do, go back and look at my very first post in this thread. What am I replying to...?

It was triggered by Yaesumofo's words that he uses his batteries "after a days rest from charging." (Bold italics added for emphasis.) It says not "under load of the BCD396T" -- after all, the BCD396T cannot run for a full day on AA batteries, can it? -- but after a day's rest. See the keyword "rest?" I repeat "rest" to make it easier for you to see, because you apparently missed rest before; You also apparently missed how Yaesumofo did this before they came in contact with his BCD396T. I demonstrated the amount of charge that is lost after the first day's rest. That's it...! Nothing more, nothing less...! The BCD396T has absolutely nothing to do with this whatsoever.

Then you and everyone else who is nitpicking my findings decided to twist them around and apply them to something that was never their intent.

 

[pyeman99]

do you have a link to the 9000?
I saw this one that looks pretty good.

http://www.thomas-distributing.com/maha-mh-c801d-battery-charger.htm

Hers a link for the guys in UK http://www.mahaenergy.co.uk/

 

[loumaag]

Well this has gone far enough. Thread Closed.

BTW emt331000, your initial response (post #55) made more sense then the edited version above. Of course neither you nor slicerwizard can see the forest for the trees as you are both talking about two different subjects. If you and he wish to carry on, make sure you do it via PM.