In the photos sharpfork2 posted the battery is listed as a McNair Li-Poly rated at 1600mAh at 7.4 volts. These types of batteries are typically 3.7 volts. I have a feeling the device is stepping down the voltage to 3.7 volts, which would effectively make the battery the same as a 3.7 volt battery at 3200mAh at the rated wattage. I think this is why people are seeing performance they would expect from a 3000mAh battery.
The battery in the Pandigital Novel
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Nothing like getting a battery naked to start the day!It really is a 7.4V battery. Wires are just doubled up to handle possible current requirements.Very very little in the way of battery protection. Pretty much nil. Verbal description should the pictures go away.The black covering is a plastic adhesive wrapper.Under that is a stamped metal sleeve that houses the batteries and plastic framework.They are two generic LiPoly batteries attached to a basic battery protection PCB. Hope PDN didn't pay much for this battery, almost would have probably been cheaper to put down two connectors on the main pcb and drop in two 3.7v batteries and connect them in the pcb instead of a fancy battery + carrier. You can see from the close up the wiring coming from the PCB where the 2 reds are soldered together (ditto for black)
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Damn The one interesting part of the whole exercise, is that based on the size etc, one could conceivably get two batteries that are a couple mm thicker, wider an longer (ie the frame/case space) and put them in. Probably would end up getting only 10-20% battery life increase.. nothing to write home about unfortunately.
The one interesting part of the whole exercise, is that based on the size etc, one could conceivably get two batteries that are a couple mm thicker, wider an longer (ie the frame/case space) and put them in. Probably would end up getting only 10-20% battery life increase.. nothing to write home about unfortunately.
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My thoughts exactly.Couldn't USB charging be theoretically possible given that these are 3.7v batteries? USB runs 5v: more than enough to charge a 3.7v battery. But I assume you would need to charge them in parallel, where I would imagine they are connected in series... but that's doable, right?My bad, if I'm way wrong. I know just enough about electrical engineering to be dangerous.oneglory;30191 said:
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you can get somewhat bigger cells in there, but you will be limited based on LiPoly technology- IE its effectively a linear relationship of cell size to capacity. (Removing the "crappy budget battery" vs the quality name brand battery comparison) So you will only get an percentage increase roughly equal to the precentage increase in cell size. It won't be much. The biggest gain would be if McNair used cheap-a$$ chinese LiPoly's that won't hold a long charge and have a lower than average current capacity. I;ve been seeing that with alot of the 18650 that have flooded the market. listed as "2800mah" but after several proper charge cycles, they settle lower (down as far as 2000-2100) The sanyo's and other japanese high quality control ones hold very close or even above rating. Its all about quality The topology inside the unit is to take 7.4V and step it down to all the parts inside, as jackbox said earlier. You would have to do a step-up (boost converter design) from 5V to charge. 7.4V & 1600mAh = 3.7V @ 3200mAh = 11.84 Watt-hours = 5V @ 2,368 mAH USB for charging will max out around 1800 mAh and for usage aka power your ipod if the battery is dead, roughly 1500mAh.Their design is just too power hungry for quick battery charging, and powering the device etc. Design compromises... usual thing.And for fun math, 12v would be 986 mAh (just under 1Amp)Could you design it to charge from USB. sure, but you would be limited to the current draw. So even if they went to 3.7, but kept to cells in parallel (bad idea, better to go with one larger sized cell) now you are at 3000 -3500 maH on the cell.. that equates to 11-13 Watt-hours of power.The draw to charge quickly on the 5V usb would be , 2200 -2600 Wh. So now you have to limit your charge capacity, leave some margin, tell the usb port you are requesting 1500 mA max, so you now charge at 1/2C to 2/3C aka if the battery takes 1 hour to charge, now its taking up to 2 hours to charge, people generally dislike to wait for their device to charge. And the longer it takes , well it gives a negative impression overall. Anyways, enough of the dirty EE talk
The topology inside the unit is to take 7.4V and step it down to all the parts inside, as jackbox said earlier. You would have to do a step-up (boost converter design) from 5V to charge. 7.4V & 1600mAh = 3.7V @ 3200mAh = 11.84 Watt-hours = 5V @ 2,368 mAH USB for charging will max out around 1800 mAh and for usage aka power your ipod if the battery is dead, roughly 1500mAh.Their design is just too power hungry for quick battery charging, and powering the device etc. Design compromises... usual thing.And for fun math, 12v would be 986 mAh (just under 1Amp)Could you design it to charge from USB. sure, but you would be limited to the current draw. So even if they went to 3.7, but kept to cells in parallel (bad idea, better to go with one larger sized cell) now you are at 3000 -3500 maH on the cell.. that equates to 11-13 Watt-hours of power.The draw to charge quickly on the 5V usb would be , 2200 -2600 Wh. So now you have to limit your charge capacity, leave some margin, tell the usb port you are requesting 1500 mA max, so you now charge at 1/2C to 2/3C aka if the battery takes 1 hour to charge, now its taking up to 2 hours to charge, people generally dislike to wait for their device to charge. And the longer it takes , well it gives a negative impression overall. Anyways, enough of the dirty EE talk
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From what I've read (battery university/other blogs), there's a limited number of charges to Lithium batteries.Lithium batteries degrade due to heat.For laptops, the recommendation is to use the charger whenever possible. And to charge as often as possible with monthly (or so) full drains. What I never understood is the comment that "charging when 50% empty will allow for more charges". HUH?Well, 10 x 0% full = 20 x 50% full charges, so what difference did it make since the number of full charges is limited?No good explanation was really given.So what I do is try not to let the Novel drain down 100%. I'll charge after each use. Not sure if that is good or not or even correct.(NOT APPLICABLE TO THE NOVEL and OFF TOPIC)Personally, I had an older laptop whose DC jack started to wiggle. I surmised that it's easier to get a spare battery than to replace the DC jack (which I tried, but ended up shorting something else). So, I find using the battery more efficient and safer than having the jack plugged in all the time.
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Has anyone found a supplier for a replacement battery for the Novel? I have also considered adding a second battery in parallel to extend the reading time between charges.
To the person who took their battery apart. That was mean. Poor battery. I don't understand why the PDN doesn't use the USB port for charging like most other devices do nowadays. I hate having to plug in a charger in the side. Plus, if it was USB it would charge whenever I was playing around with ADB or transferring files, like my Chinese made (Thai branded) Android 2.1 phone does.
I don't understand why the PDN doesn't use the USB port for charging like most other devices do nowadays. I hate having to plug in a charger in the side. Plus, if it was USB it would charge whenever I was playing around with ADB or transferring files, like my Chinese made (Thai branded) Android 2.1 phone does.
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PDN didn't use the USB for probably several design reasons... one (which was mentioned by me in some other post) was USB has current limiting for charge. So it would take quite a long time to charge. Why doesn't your laptop charge from a usb port? Think of the Tablet more like a laptop than a cell phone.Yea I was a mean bugger taking apart the battery I wouldn't try to find a supplier for the battery per say... PlaceHolder for powerizer.com and other similar places could build up a 2 cell pack with shrink wrap and the right connector. ymmv etc.It would be easier (in my view point) to just have a 12V pack connect externally. Just a thought.Spincontrol - you got the gist right,.. heat... heat causes oxidization causing higher internal resistance, causing less charge to be available etc...the linear example isn't correct... because the battery is analog in nature... 1 0-100% charge doesn't equal 2 50-100% charges. Due to the battery having to accept charge to be recharged you are dealing with heat, pushing electrons around etc... So the length of "time" a battery lasts is very dependent on how well it is treated.
I wouldn't try to find a supplier for the battery per say... PlaceHolder for powerizer.com and other similar places could build up a 2 cell pack with shrink wrap and the right connector. ymmv etc.It would be easier (in my view point) to just have a 12V pack connect externally. Just a thought.Spincontrol - you got the gist right,.. heat... heat causes oxidization causing higher internal resistance, causing less charge to be available etc...the linear example isn't correct... because the battery is analog in nature... 1 0-100% charge doesn't equal 2 50-100% charges. Due to the battery having to accept charge to be recharged you are dealing with heat, pushing electrons around etc... So the length of "time" a battery lasts is very dependent on how well it is treated.If the battery components, packaging and controlling electronics were all designed correctly, you should not have to worry about level of charge, usage characteristics, etc. Unfortunately, a lot of times they are not, and result in problems if fully discharged, or fully charged. If you are referring to the "memory effect" of Ni-Cd's, no it does not apply to Li-ion or Li-poly.
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