Battery Voltage
- Thread starter bennollan
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Well it's a standard lithium-ion polymer battery, which would imply a maximum charge to 4.23 volts. If you overcharged it, the battery would be damaged, but the built-in charger is designed to prevent this.X x Ben x X said:
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WizardStan
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It's 3.7 volt. That's always been the standard I've heard. Either 3.7, 5.0, or some 1.5x amount.
A quick google search (4.23 volts vs 3.7 volts) agrees with me. I'm honestly curious where you got the 4.23 number.
A quick google search (4.23 volts vs 3.7 volts) agrees with me. I'm honestly curious where you got the 4.23 number.
WizardStan said:
Most lithium batteries are used from around 4.2 volts fully charged, to around 3.0 volts discharged. 3.7 volts is the nominal voltage. Those voltages are determined by the hardware, and sometimes software, depending on the device, following the battery manufacturers recommendations. I think I remember it being mentioned that the Pandoras battery charging hardware can be controlled by software, so those voltages can be changed.
I'm curious where you got 5.0 or some 1.5x amount, lol.
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I figured Ben was talking more in terms of the number of cells the battery is. (Since it charges via USB, I'm going to go out on a limb and assume one cell; stepping voltage up to charge more would probably be prohibitive.)
As far as peak charging voltage affecting lifespan, the answer is "yes". Limiting the charge of a lithium battery to 90% of its peak charge will add a non-trivial amount to its lifespan. On the other hand, rechargeable lithium batteries will do their damnedest to digest themselves within four years just sitting on a shelf, so you might as well make the most of it while you've got it. Of course, that could just be the R/C helicopter enthusiast in me commenting on the disposability of LiPo batteries in said hobby. In any case, with the claimed battery life being as long as it is, you can expect the thing to last a good two or three years unless you're hammering away at the thing 24/7.
As far as peak charging voltage affecting lifespan, the answer is "yes". Limiting the charge of a lithium battery to 90% of its peak charge will add a non-trivial amount to its lifespan. On the other hand, rechargeable lithium batteries will do their damnedest to digest themselves within four years just sitting on a shelf, so you might as well make the most of it while you've got it. Of course, that could just be the R/C helicopter enthusiast in me commenting on the disposability of LiPo batteries in said hobby. In any case, with the claimed battery life being as long as it is, you can expect the thing to last a good two or three years unless you're hammering away at the thing 24/7.
lulzfish
Pandora Defense Squad
Life as in number of charge cycles or as in hours of operating time per cycle?X x Ben x X said:
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WizardStan
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1.5x because for those based on standard battery cells (ie, AAs), and I've seen 5.0 on the occasional USB device with a built in battery.beanoman said:
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Tor
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The battery settings on a standard Palm T3 are as follows:
Charge cutoff: 4.24 volts (which will let the voltage drop to 4.20V when charger is removed)
Warning : 3.78 volts (that's when the low battery warning comes up)
Critical : 3.76 volts (that's when it starts to shut down services and eventually switch off screen)
These values can be adjusted by a 3party application. By experimenting people have found that limiting the charge cutoff to 4.10 volts will give the battery a slightly longer life, and reducing the critical limit will give you a longer usage time, but going below about 3.65 volts makes the device unreliable. And, as tested on other devices, draining the battery down below 3.5 volts starts to seriously degrade the battery. [Edit: There are tons of discussions and threads about experimenting with these things if you go over to the brighthand forum and search the archive.]
So yes, it's correct to say that the voltage of a lithium battery is 4.1 - 4.2 volts, and the 3.7v label is really the lower usable voltage. At 3.88 volts my T3 says "54%" right now, for example.
Charge cutoff: 4.24 volts (which will let the voltage drop to 4.20V when charger is removed)
Warning : 3.78 volts (that's when the low battery warning comes up)
Critical : 3.76 volts (that's when it starts to shut down services and eventually switch off screen)
These values can be adjusted by a 3party application. By experimenting people have found that limiting the charge cutoff to 4.10 volts will give the battery a slightly longer life, and reducing the critical limit will give you a longer usage time, but going below about 3.65 volts makes the device unreliable. And, as tested on other devices, draining the battery down below 3.5 volts starts to seriously degrade the battery. [Edit: There are tons of discussions and threads about experimenting with these things if you go over to the brighthand forum and search the archive.]
So yes, it's correct to say that the voltage of a lithium battery is 4.1 - 4.2 volts, and the 3.7v label is really the lower usable voltage. At 3.88 volts my T3 says "54%" right now, for example.
Exophase
Nothing good will ever come of Exophase.
The lower limit threshold will depend on the device, but I'm surprised that Palm T3 starts getting unreliable at something as high as 3.65V. Lithium ions can go all the way down to 2.7 or so, but after 3.6-3.7 it starts dropping like a stone. It also drops from 4.2 very quickly, to around 3.8-3.9. These are just rough values, but the curve will spend most of its time around the 3.8 mark.
Ideally fuel gauges would be measuring current, not voltage, since the voltage curve is very non-linear and during most of the interesting portion changes in tiny amounts. It'll also vary a decent amount from battery to battery, maybe there's something about the ones Palm was using that makes them a little higher output than normal.
Check out the curves on this page:
http://www.mpoweruk.com/performance.htm
Ideally fuel gauges would be measuring current, not voltage, since the voltage curve is very non-linear and during most of the interesting portion changes in tiny amounts. It'll also vary a decent amount from battery to battery, maybe there's something about the ones Palm was using that makes them a little higher output than normal.
Check out the curves on this page:
http://www.mpoweruk.com/performance.htm
WizardStan
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Well there you go. Learn something new everyday. ThanksTor said:
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Tor
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If I'm not mistaken most phones (normal ones, I don't know about smartphones) will discharge the battery to a much lower voltage than my T3. This can have consequences though. I used to have an S-E T630 (I think that was the designation) where just before the Christmas holidays its multiconnector broke. So I couldn't charge it.Exophase said:
I kept the phone runnning over Christmas, and, as it was a work phone, asked for a replacement when work started up again in January. After a few days I got a new, bare phone. My old one was still alive (I had kept phone calls to the minimum during the time, of course). I turned it off for the final time, and moved the battery over to the new phone. By that time it had kept for about 3 weeks, running (except for being switched off some nights) on the same charge. Charged it up, started to use the new phone.
But now the battery could only hold 2 days of charge, that deep discharge, which was still not enough to switch off the phone, had completely destroyed the battery's capacity.
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El Jefe
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If I buy 2 pandora batteries, can I put them in parallel to double the battery life?
Would it work with a battery from another manufacturer, but with the same voltage rating?
If neither of those works, would the best way to add extra battery power to go through the charging port off the battery?(as opposed to usb) as I understand those would be less finicky in regards to voltage drops over time.
Would it work with a battery from another manufacturer, but with the same voltage rating?
If neither of those works, would the best way to add extra battery power to go through the charging port off the battery?(as opposed to usb) as I understand those would be less finicky in regards to voltage drops over time.
Tor
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You could in principle put the batteries in parallel, but you can't in practice. There's no room at all. If that had been the case then we would probably have been getting a larger battery with twice the capacity to start with! As it is, the monstrous 4000, or 4200 mAh battery we're getting is probably the largest capacity battery in the business, for this kind of device. I for one expect to be completely happy with the Pandora's battery capacity. I've been pretty happy with the 1500mAh battery in my N800, which I use all the time and only had to charge once or twice a week. After 2.5 years the battery started to sag though.
As it is, the monstrous 4000, or 4200 mAh battery we're getting is probably the largest capacity battery in the business, for this kind of device. I for one expect to be completely happy with the Pandora's battery capacity. I've been pretty happy with the 1500mAh battery in my N800, which I use all the time and only had to charge once or twice a week. After 2.5 years the battery started to sag though.
Polossatik
I reject your reality and substitute my own
Pleng said:
Depends, If the (internal) charging system is designed to max charge to 4.10 ~ 4.15v and to consider the battery "dead empty" (device refuses to even start) at 3.0 ~ 2.9v then this is not a problem.
You can perfectly "discharge" the battery then because the "empty" level is above what will provoke damage to the battery.
It however "limits" the amount of charge you could get out of it to approx 90% ~ 95% of what you could get when going to 4.20v and 2.7v for example, but this will greatly reduce the lifespan of the battery, The little added "battery runtime" is IMHO not worth killing the battery :rolleyes: .
Would be nice to know what limits are set in the pandora (and this should ideally NOT be "user configurable" in anyway), so that if people use a external charger (or build one) they know what the pandora uses.
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