Centro vs Pre Batteries - Voltage Readings and Differences

[itsjustme]

Quick background info:
Husband is a former diesel mechanic who used to work on or diagnose ECMs - the "brain" or central computer in big trucks. He bought a digital Fluke meter to do that as there really is no margin for error when working on .

I have three Centro batteries and a brand new battery-eating Pre.

When I saw how quickly my new Pre depleted its battery and checked the price of a new one, I came here to see what the users here had to say. I saw a lot of arguments either way, so I took my new Pre and my Centro out to the shop for a battery diagnosis.

There are three contacts on each battery. Here are the readings for each battery by contact set. The X's indicate the contacts tested. They are not labeled as negative, control, or positive, but we assumed that was the order in which they were arranged. Either way...

The Centro
Left----Center----Right
X-------------------X =4.15V
X---------X--------- =3.62V
---------- X---------X =00.1V

The Pre Plus battery
Left----Center----Right
X-------------------X =00.1V
X---------X--------- =3.17V
---------- X---------X =3.17V


These numbers are almost opposites of each other. I was always told that you could starve a device for electricity or slightly jack it up and still have a device that runs, BUT the lifetime of the device would be shortened in a correlation to the degree of error in the charge.
(or too much or too little = premature phone death)

I've read where a lot of folks are using their Centro batteries in their Pre's and are content with that. I don't think that I could do that. It took me about two days to figure out how and to patch my phone, and once I got it customized like I wanted it, I think I love it.

I can't afford to just buy one, so I'm going to take the safe road and stick with the made-for-Pre batteries.

Please don't flame me if you have chosen to use your old Centro batteries - I would never, ever tell you what to do with your phone. I was just fortunate enough to get some very real specs and thought that I would share them with you guys, as I have learned SO MUCH from here. I'd have sent this thing back if I hadn't found this forum.

[andidendel]

Very interesting. Thank you.

[nrcsbrooks2]

wow..thanks. I just think it'd be better to use the ones designed for the Pre anyways imo

[Trekker]

Originally Posted by itsjustme

There are three contacts on each battery. Here are the readings for each battery by contact set. The X's indicate the contacts tested. They are not labeled as negative, control, or positive, but we assumed that was the order in which they were arranged. Either way...

The Centro
Left----Center----Right
X-------------------X =4.15V
X---------X--------- =3.62V
---------- X---------X =00.1V

The Pre Plus battery
Left----Center----Right
X-------------------X =00.1V
X---------X--------- =3.17V
---------- X---------X =3.17V


These numbers are almost opposites of each other.

I'm not seeing that at all. My Pre and Centro batteries are reading the same. I took measurements with the Palm label facing up and the 3 contacts facing me. With that orientation, the 3 contacts are from left to right: positive, control (I'll use that term since that's what you call it), negative.

Both my Pre and Centro batteries are partially depleted but they read identical, not opposite as you say yours are reading. See pictures below.

One interesting note, when I measure the outer two contacts (positive and negative) on the centro, the voltage is stable. When I measure it on the Pre, after about 5 seconds the voltage drops to zero. I have to "reset" it by placing my positive DMM lead in the center contact (negative lead on right contact), then I can move the positive lead back to the far left and get my voltage reading again. So, in that respect, the Pre battery is acting differently. I have a few other centro batteries but I think they have no charge so I'll have to charge them up to check.

So, my tests don't correspond to yours. I probably need to fully charge both batteries and then do the tests but decided to try it with what I have.

With the Centro battery on left, Pre battery on right, the contacts from left to right are positive, control and negative.


Here are my voltage readings:

[itsjustme]

How wild! Both of mine were fully charged, but I don't know how much difference that really makes.
I've got a new OEM Pre battery coming, and when it gets here, I'll see if I can get my other half to test a second set. He's pretty tolerant of me that way.
BTW, what make/model meter are you testing with?

[Trekker]

Originally Posted by itsjustme

How wild! Both of mine were fully charged, but I don't know how much difference that really makes.

I just pulled the Centro battery off the charger so it should be fully charged. The only difference is that the first reading is now 4.15 (was 3.86) and the second is 0.18 (was 0.15.)

Originally Posted by itsjustme

BTW, what make/model meter are you testing with?

I'm just using a cheap meter I got at Lowe's. Greenlee model DM-20. I used to have a Fluke but it's probably buried in a box in a closet somewhere. I know Fluke's are great meters (I use one at work) but in a simple test such as this, I don't see it making a difference.

I'll charge my Pre battery and see what it reads fully charged. I also have a Mugen 1400 that I use daily, maybe I can pull that and try it also.

[itsjustme]

Originally Posted by Trekker

I'll charge my Pre battery and see what it reads fully charged. I also have a Mugen 1400 that I use daily, maybe I can pull that and try it also.

I'm hoping my new Pre battery will show up today so I can do a repeat on a different set than the first pair (already have a bunch of OEM Centro batteries of various ages).

I really am glad that you are doing this, too. I don't care who is right. I just want to know the *truth*. There's been too much debate without enough concrete evidence, and while the idea of having like six extra batteries is both funny and appealing, I am so afraid to chance it. It was unpleasant enough paying the upgrade fee - I couldn't justify the whole cost to replace it.

[Jochen K.]

Hi,

I'm afraid I'm cross-posting here - I wrote the same thing over on the Treo Central thread at

http://discussion.treocentral.com/sh...=1#post2531965

But I'm not sure how many from this thread look over there, so...

With an old (once very expensive) analogue voltmeter I get basically the same results as itsjustme; I've mailed them to the accessory dealer who sells Centro batteries for use in the Pre; I'm waiting with great interest for their response.

Regards,

Jochen

[lazslo11]

I was wondering what the third contact was for. I found this on the web.


"So I talked to the battery charging experts at Maxim/Dallas Semiconductor. Maxim is one of the major suppliers of battery charging ICs and fuel gauges. They said, yes, the majority – but not all – of cell phones have a thermistor in the battery pack that tells the charger when the temperature is below freezing and prevents the battery pack from charging. They estimated that 80 - 90% of cell phones have this capability. A good way to tell is by looking at the contacts on the battery pack: Two contacts means no temperature sensing capability, a third contact is probably for the thermistor and indicates the charging indeed shuts down at sub-freezing temps. (A fourth contact is probably for a memory device.)"

[Trekker]

I checked out my Mugen 1400 at work today using my Fluke DMM. It was partially discharged and it behaved the same way as the Pre battery (Left and Right contacts read 4.09 volts for 5 seconds, then dropped to 0 volts.) Had to reset by using the positive lead and touching the center contact. This is exactly how my Pre battery behaves but the Centro battery does not.

One interesting thing, I was also getting a voltage reading between left and center (3.523 volts) using the Fluke but when I came home and used my cheap DMM, I did not get 3.523 between left and center, I got 0.xx volts so it does appear that the meter does make a difference.

In any case, the Left and Right contacts were identical on the Centro, Pre and Mugen batteries, they all read 4.x volts.

I'll do some more testing this weekend on all 3 batteries and I'll see if I can dig up my Fluke DMM to use.

[DaDueler]

Interesting discussion, I wonder if we could get someone from Palm to weigh in...

[OldSkoolVWLover]

Bah you are all gonna make me bust out my meters this weekend now, and my centro batteries are buried somewhere in a drawer

[gitit20]

Originally Posted by itsjustme

Quick background info:
Husband is a former diesel mechanic who used to work on or diagnose ECMs - the "brain" or central computer in big trucks. He bought a digital Fluke meter to do that as there really is no margin for error when working on .

I have three Centro batteries and a brand new battery-eating Pre.

When I saw how quickly my new Pre depleted its battery and checked the price of a new one, I came here to see what the users here had to say. I saw a lot of arguments either way, so I took my new Pre and my Centro out to the shop for a battery diagnosis.

There are three contacts on each battery. Here are the readings for each battery by contact set. The X's indicate the contacts tested. They are not labeled as negative, control, or positive, but we assumed that was the order in which they were arranged. Either way...

The Centro
Left----Center----Right
X-------------------X =4.15V
X---------X--------- =3.62V
---------- X---------X =00.1V

The Pre Plus battery
Left----Center----Right
X-------------------X =00.1V
X---------X--------- =3.17V
---------- X---------X =3.17V


These numbers are almost opposites of each other. I was always told that you could starve a device for electricity or slightly jack it up and still have a device that runs, BUT the lifetime of the device would be shortened in a correlation to the degree of error in the charge.
(or too much or too little = premature phone death)

I've read where a lot of folks are using their Centro batteries in their Pre's and are content with that. I don't think that I could do that. It took me about two days to figure out how and to patch my phone, and once I got it customized like I wanted it, I think I love it.

I can't afford to just buy one, so I'm going to take the safe road and stick with the made-for-Pre batteries.

Please don't flame me if you have chosen to use your old Centro batteries - I would never, ever tell you what to do with your phone. I was just fortunate enough to get some very real specs and thought that I would share them with you guys, as I have learned SO MUCH from here. I'd have sent this thing back if I hadn't found this forum.

Very good!

I did the same test before i posted the results But i went a little bit further I fully charged the battery's for Pre and Centro 30min after charge on both i checked the voltages both were right around the same voltages 3.9 battery to battery...

I also ran a load test to see how they held up the centro battery died a bit sooner then the pre battery but that's because its 2 years old vs a new pre battery after all the testing and so on i took both cells apart they are both identical inside both have the same controller chip and both controllers provided the same response when tested in my test set up...

I am big in to RC and have some really smart chargers that can talk to the controllers it was simple as building a small connector to hook to the battery I was able to program the charger with the MAH of the battery and run a load test and a health check

The Pre battery came back at 99.4% of rated capacity and the Centro came back at 88.7% The voltage during the test stayed even about 3.66v and the Watt Hour was at 4.1(Centro) 4.3 (Pre) (lower Watt hour because the Centro battery is 2 years old)

The charger identified both battery's as A palm branded battery each reported back that the pack firmware was 1.0 so i am totally convinced that the battery's are the same...

[gitit20]

Originally Posted by lazslo11

I was wondering what the third contact was for. I found this on the web.


"So I talked to the battery charging experts at Maxim/Dallas Semiconductor. Maxim is one of the major suppliers of battery charging ICs and fuel gauges. They said, yes, the majority – but not all – of cell phones have a thermistor in the battery pack that tells the charger when the temperature is below freezing and prevents the battery pack from charging. They estimated that 80 - 90% of cell phones have this capability. A good way to tell is by looking at the contacts on the battery pack: Two contacts means no temperature sensing capability, a third contact is probably for the thermistor and indicates the charging indeed shuts down at sub-freezing temps. (A fourth contact is probably for a memory device.)"

The 3rd pin is a data buss so it can talk to the pre there is a chip inside the battery and it reports back data like voltage temp charge rate and discharge rate health of the battery and so on

[gitit20]

Originally Posted by DaDueler

Interesting discussion, I wonder if we could get someone from Palm to weigh in...

I called palm and they told me the battery's are same sept the sticker on the out side

[zechzz]

a little background on me I'm an electronic technician for a company with contract to pretty much all the telephone equipment providers in the usa with that said I don't work on cell phones there isn't really any money in repair for those. But am familiar with power. Basically there is a contoller chip inside the battery that has a sense volatge that tells the phone to charge or not to due to how charged it is and weather or not under load. Inside the chip are diodes and transistors which act sort of like a door for those of you who don't know. Anyway you were getting the 1.40vdc because you were shorting the left and middle pins on the battery and the 3.45 vdc afterwards because you were switching the transistors inside sort of like opening and shutting a door the two outside pins give you 4vdc a .15mVdc differnce which means the voltage on the left and middle pins is going through 2 diodes or transistors or a combo which are in the chip because there is for a standard voltage drop for transistors and diodes there is a .7vdc drop. Which adds up to your .15vdc Any way I've been using my centro battery since I got my pre and it's perfectly safe for your device.

[zechzz]

@ gitit20 can you look at the chip & tell me the numbers & letters on it? I'll look up a schematic I'm thinking it's a zener diode & not a standard.

[OldSkoolVWLover]

Originally Posted by zechzz

a little background on me I'm an electronic technician for a company with contract to pretty much all the telephone equipment providers in the usa with that said I don't work on cell phones there isn't really any money in repair for those. But am familiar with power. Basically there is a contoller chip inside the battery that has a sense volatge that tells the phone to charge or not to due to how charged it is and weather or not under load. Inside the chip are diodes and transistors which act sort of like a door for those of you who don't know. Anyway you were getting the 1.40vdc because you were shorting the left and middle pins on the battery and the 3.45 vdc afterwards because you were switching the transistors inside sort of like opening and shutting a door the two outside pins give you 4vdc a .15mVdc differnce which means the voltage on the left and middle pins is going through 2 diodes or transistors or a combo which are in the chip because there is for a standard voltage drop for transistors and diodes there is a .7vdc drop. Which adds up to your .15vdc Any way I've been using my centro battery since I got my pre and it's perfectly safe for your device.

Also, correct me if I am wrong (I don't have the expertise you do but I do have some experience with electrical wiring), if the battery output was completely opposite (as posted by the OP). This should immediately fry the device (if you were powering ground and grounding power). Basically with the phone being complex circuitry, powering the wrong main lead should lead to catastrophic failure quickly, and not long term degradation...?

[zechzz]

mostly likely with it only being 4vdc it wouldn't harm anything if it were ac it might be more likely but just as if u plug in your batteries for your remote in the incorrect order there are no negative effects from such a small voltage level. the incorrect reading they got was because they switched there meter leads around it does make a difference in reading voltage in which way you connect them one red which is positive and the other black which is negative. And the debate on weather the meter was effecting the reading is rubbish any dmm should be able to pick up the small amount of 4vdc especially since there is no current draw perhaps one of the meters had low battery which can effect some readings on some meters or a blown fuse will definitely do it.

[Trekker]

Originally Posted by zechzz

And the debate on weather the meter was effecting the reading is rubbish any dmm should be able to pick up the small amount of 4vdc especially since there is no current draw perhaps one of the meters had low battery which can effect some readings on some meters or a blown fuse will definitely do it.

I would tend to agree with you but I saw some different readings when I used my Fluke at work to measure my Mugen battery. The difference was in reading just the left and center contacts. With the Fluke, I got 3.52vdc between left and center, with the cheap meter I only got 0.xx something. The cheap meter did read the outer contacts (left and right) correctly at 4.09vcd, the same as the fluke so if it was a battery issue with the cheap meter, I shouldn't have read the outer contacts correctly.

Also, the plus and minus contacts on the batteries are on the outside, the OP's original post doesn't show the voltage correctly on the outside contacts of the pre battery, so I think there may have been a mistake made, or as I've stated, after 5 seconds of reading the outside contacts of the Pre and Mugen batteries, the voltage drops to zero. Something is causing it to switch off. My Centro battery does not behave this way, you can measure the outer contacts for 10, 20 seconds and it stays the same.

Personally, I'll feel better repeating my tests with a good meter like the fluke, but as you said, I don't see how it matters in a test like this.

I would like others to repeat the tests to see what results they get, especially to see if they can repeat the issue with the pre & mugen voltage switching off and having to be reset.

Just to add my background, I've been an electronic tech for some 27 years now working on a variety of electronic systems so I'm pretty familiar with using a meter.