Develop Bugs

Project: Extended Battery Pack (to extend battery x4)

I have an on-going project of creating a battery extender for my xda and I want to share it.
This is composed of 8 rechargable NiCAD or NiMh battery connected in series to produce a 9.6 v. The 9.6 v will be regulated by a 5v regulator (LM7805) then it will be connected in the XDA power dongle.
With this project, the battery life can be x4 or more depending on the batteries used.

I'm currently (no pun intended) trialling a Mugen 4500mAh battery which looks likely to give me >16 hours continual use ob my XdaII. Probably much more expensive than your solution but perhaps more convenient being 'built-in'.
Good idea though, I could have done with your solution two years ago!

Update on my project
I already assemble it and have try it already and here is the update.
The good news is the battery is charging.
The fall back is that the regulator that I have used is emitting too much heat.
I also have done some bench test and here are the data for those who are interested.
1. XDA IIs is drainning about .700 Amperes when charging supplied by 5v
2. XDA IIs will not charge with 4.8 V or below
-I got this data using a adjustable power supply with an Ampere meter

Project Fall down
For the fall down, I think it is because of two reason:
1. It is because the total Voltage supplied by the batteries is 9.6V and the out put regulation is 5V, therefore the 4.6V is being converted to heat.
- I should have use 6 battery insted of 8 to 7.2v instead of 9.6.
2. Since 5v is the out put of the regulator and it is charging the battery with a 4.8v (for i.e.) this will mean that the .2v drop will be in the line between the charger and battry which also mean the current is the max output of the regulator (Applying OHMs Law I=V/R, and R being 0 will result to infinity in theory and maximum in reality)
____________
| |
V1=5V V2=4.8V
|___________|
-I think I should have put a resistor to control the current or I should have designed a regulated current supply instead of a regulated voltage supply
For the #2 reason i'm not still sure about this because, this can only be true if the XDAIIs or it's battery does not have a built in charging circuit.
I have read some articles on mugen battery that it has a overload protection circuit my guess is that XDA also have it my I dont have any information yet. Incase XDAIIS or the battery alreadhave a charging circuit I only need to resolve my #1 Fall down.
I think I need to do more research, but if anybody could provide me information it will be highly appreciated. XDAIIs service manual maybe a greate help.

resolved
My project is now working, the over heating was resolved by putting a heat sink on the IC regulator and reducing the numbers of AA battery to 6 pcs (6 x 1.2 =7.2).
I'm still not sure where the over charging protection circuit is installed (XDA unit, battery or in the power supply/Craddle) incase it is not with the xda or the battery then I need to be carefull not to overcharge my battery with my project but if it is in it then my project is now perfect.
Any body knows where the over charging protection circuit is please help.

Re: resolved
there is a russian link for the same project - http://forum.pocketz.ru/index.php?showtopic=11339&hl=battery extender&st=100
Adapter:
http://wince.box.ru/russian/caradapter.htm
typically you can take any car adapter, give 12v to its input and take 5v from output for charging your PocketPC battery. Most car adapters would give 5V output if input is between 8...12V

hi kabayan,
i think the over current protection is in the device.
i converted an external battery charger (using 4x AA battery) intended for blue angel to my himalaya. there's nothing inside it except for a 10K resistor in series with the output.
i also noticed that even with the correct regulated voltage applied, my hima won't charge without a current limiting resistor, so its definitely an over current protection in the device!
congrats in your project!

Schematic Diagram
Anybody has a schematic diagram of XDA? Please share

If you have the money might as well buy additional battery so no need for you to go thru all thoses stuffs. My project had work for me actually it is easy just basic ohms law. The challenge I have encountered in the project was the heating up of the regulator but it was resolved. by the way the reason I made a battery extender is because that time extra battery is not easy to find and I dont have a budget for it so I just salvage some electronic parts from my previous projects. But now I already bought an extra battery- a lot convience than before

High current USB charging (mains, car or battery pack)

Caution: only for people with electronica experience who are aware of riscs such as electrical shocks, fire and damage to equipment.
If third party USB chargers are used, charging current may be limited, as I noticed at my iPAQ 314.
I measured the signal wires of HP charger's USB; it was 3V with an Ri of 4K.
So I set up the next circuit which mimicks this on a 3th party charger with can deliver 5v, 1A:
red --6k8-- white --10K-- black
red --6k8-- green --10K-- black
This works for the iPAQ 314 and also for the HTC HD2.
I added this circuit to my battery pack (4 x NiMH serial) with the 10K resistors connected to the cable shield to prevent discharging while not connected.
When the plug is inserted in the iPAQ, shield is connected to the black wire via the iPAQ. Also this works OK.
With 2300 mAH cells, the battery pack contains up to 11.5 WH, wich is more than twice the capaity of a 1350 mAH Li-Ion battery.
Caution: only use NiMH, otherwise the higher voltage may damage your equipment.
Caution: use a 2A fuse to avoid problems due to short circuits.
The max voltage of the battery pack may be 5.6V this is .35v higher than the USB spec, but it drops rapidly to within the spec.
I used such a battery pack for several years now, on the iPAQ 314, iPAQ 2210, HTC P2650 without experiencing bad effects and I will use it on the HD2 as well.

Do you have any schematic diagrams to explain what your saying ?
Thanks

I verified that the circuit works OK with the HD2.
As for the diagram: look again, it's there!
Have fun, Bert

Wired charging not working - Help identifying a broken component

The charging port on my Nexus 7 2013 starting playing up and only charging when the cable was held in certain positions and then finally it stopped working altogether.
I took it apart to replace the port and the problem was that the legs on the connector had actually lifted the tracks off the board.
I replaced the connector and wired the legs to the nearby pads the tracks I believe they're supposed to go to and when plugged in both the charging symbol appeared and usb data communications worked.
However I then had a slight mishap while handling it and managed to knock off and break the component pointed to by the arrow in the photo.
The component has no markings on it and is about 2mm x 1mm. I can't measure the original with a meter as it's physically broken.
Can anyone tell me what the component is so that I can replace it?

I meant to also add that while looking for info I came across this site regarding the port repair which some people may find useful although personally I think you're better of removing the sub board and then using a proper desolder station if you have access to one.
http://freemansgarage.com/blog/?p=1082

Ollie2 said:
what the component is so that I can replace it?
Click to expand...
Click to collapse
This component has a sub-ohm resistance and is a fusible resistor or choke/inductor. Either way you can just short/bridge it - no worries

k23m said:
This component has a sub-ohm resistance and is a fusible resistor or choke/inductor. Either way you can just short/bridge it - no worries
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Click to collapse
Thank you very much for the reply, that's just the kind of answer I was hoping for.
With the link bridged the device does show it as charging when plugged in however the charging rate is now really, really slow and at it's current rate of charge looks like it'll take about 50 hours to fully charge.
If I put an ammeter across the two pads then it looks like it pulls about 85ma whereas I'd expect it to be more like 10 times that.
I've tested it with several cables and chargers (0.5A, 1A and 2A) that used to work perfectly with it previously and still work with other devices..
I've ordered an inline usb ammeter that should arrive later today to double check the current usage but the charger or battery don't get warm so I'd guess it's correct.
The repaired tracks look to be correct and beep through fine, the data cable works and I can transfer data but presumably there is something else wrong with it.
Any suggestions of what else to look or is there anything that I need to do with software to reset the charging process?

Ollie2 said:
If I put an ammeter across the two pads then it looks like it pulls about 85ma whereas I'd expect it to be more like 10 times that.
Click to expand...
Click to collapse
The ammeter's internal resistance may trigger N7's lower charging current draw which normally happens to prevent overloading USB2 or weak chargers.
Anyway, do a recalibration:
fully discharge N7
recharge it completely while off
disconnect the charger and turn N7 on

Thanks for the reply.
I added the ammeter inline as it was charging so slowly and the 85ma it looks to pull roughly equates to the charging times I'm seeing.
The tablet is fully charged at the moment (via a wireless charger) but when it's not needed for a few days I'll flatten the battery and let it charge using the cable, I'd guess it'll take 2-3 days to do so.
Interestingly apps such as ampere show the sort of current I'd expect the device to be getting in the 800ma range however I'm guessing it's calculating this as the requested current but it's just not making it to the battery for some reason.

My T800: Your device is overheating.

I have been browsing the web when suddenly my apps shut down and I got this message. This happened twice. What's going on?

Here are some screenshots

Maybe find the offending app?
Try booting in safe mode.

The same thing happens in safe mode. I suspect it has more to do with the fact that I recently opened the back cover to replace the USB connector and left speaker. Maybe I have disturbed contacts or some cooling components on the mainboard.

Akopps said:
The same thing happens in safe mode. I suspect it has more to do with the fact that I recently opened the back cover to replace the USB connector and left speaker. Maybe I have disturbed contacts or some cooling components on the mainboard.
Click to expand...
Click to collapse
Did you disturb the heat sink on the cpu?If you did you will need some heat sink compound to mount it properly to the heat sink.

I run geekbench with the cover open and as the tablet was heating up I touched the backs of all mainboard parts and it appears that the part that gets hot is where the USB charger cable plugs into it. So I am guessing that this is related to the incident when I apparently "fried" the USB charger by plugging it into a malfunctioning USB hub. I changed the USB charger and its connector, but I guess this did not help.
I could change the mainboard if I could find one cheap. Gosh, those things are expensive. I see vendors selling them on ebay for well above 100USD, a surprising price for a three year old, used part. Those that are cheaper are sold already defective. For comparison, the mainboards of Samsung Galaxy S5 phone, which was a 2014 device of comparable performance are sold for just 30 bucks.

Akopps said:
I run geekbench with the cover open and as the tablet was heating up I touched the backs of all mainboard parts and it appears that the part that gets hot is where the USB charger cable plugs into it. So I am guessing that this is related to the incident when I apparently "fried" the USB charger by plugging it into a malfunctioning USB hub. I changed the USB charger and its connector, but I guess this did not help.
I could change the mainboard if I could find one cheap. Gosh, those things are expensive. I see vendors selling them on ebay for well above 100USD, a surprising price for a three year old, used part. Those that are cheaper are sold already defective. For comparison, the mainboards of Samsung Galaxy S5 phone, which was a 2014 device of comparable performance are sold for just 30 bucks.
Click to expand...
Click to collapse
try to resolder the USB connector, if there is bad joint, that could cause a larger than expected resistance on the 5v or 0v return, this will act as a heating element at the solder joint.
In normal operation there can be up to 2A flowing through that connector, it will heat +10 degree even when functioning correctly, any extra resistance at that point is dangerous since its almost maxed out on thermal dissapation anyway.

Akopps said:
I run geekbench with the cover open and as the tablet was heating up I touched the backs of all mainboard parts and it appears that the part that gets hot is where the USB charger cable plugs into it. So I am guessing that this is related to the incident when I apparently "fried" the USB charger by plugging it into a malfunctioning USB hub. I changed the USB charger and its connector, but I guess this did not help.
I could change the mainboard if I could find one cheap. Gosh, those things are expensive. I see vendors selling them on ebay for well above 100USD, a surprising price for a three year old, used part. Those that are cheaper are sold already defective. For comparison, the mainboards of Samsung Galaxy S5 phone, which was a 2014 device of comparable performance are sold for just 30 bucks.
Click to expand...
Click to collapse
Actually there's no need to change mainboard. This is a common problem of Samsung tablets when battery connector has cracked solder joints.
This is an example
Anyone knows how to solder can do it within 5 minutes
This is an example for a Tab 3, but similar to any Samsung tablets, most use the same battery connector
I fix mine and other tablets having problem of quick discharge, charging or overheating just by resolder the battery connector.

I just picked up an allegedly working T800 with 32GB board (!!) and a cracked screen for only 89 bucks on ebay. Considering my mad soldering skillz, I probably would need to have a backup board anyways, plus I could use this tablet for other spare parts, like the battery. The attachment shows precisely the area that seems to get hot to touch.

so would 50c for the cpu and battery be normal for this tablet? (was running a game)

?my was boost on 1600Mhz 81°C all the time

P605 dead, what to do next?

My P605 has no sign of life.
Internal charger doesn't seem to be working at all. So I've charged the battery with my bench power supply, resoldered the battery connector. Measured the connector on the board and it shows battery voltage. When connected through a USB power monitor the device doesn't seem to draw any power whatsoever though.
Is there some common hardware problem I should be looking at apart from dead battery/bad battery connector?
I do have a hot air rework station, fairly decent soldering skills, bench supply and oscilloscope but nothing super fancy,.

Anduhroid said:
My P605 has no sign of life.
Internal charger doesn't seem to be working at all. So I've charged the battery with my bench power supply, resoldered the battery connector. Measured the connector on the board and it shows battery voltage. When connected through a USB power monitor the device doesn't seem to draw any power whatsoever though.
Is there some common hardware problem I should be looking at apart from dead battery/bad battery connector?
I do have a hot air rework station, fairly decent soldering skills, bench supply and oscilloscope but nothing super fancy,.
Click to expand...
Click to collapse
The usb assembly tends to fail & can be cheaply replaced, but as you already charged the battery externally, there must be another problem.
I found it difficult to attach the connector of my new battery, required a lot of pressure, and to arrange the battery cable such that it won't push up the connector. There was hardly room for the battery cable, as it was two or three millimeters longer & the wires quite stiff.

lecorbusier said:
The usb assembly tends to fail & can be cheaply replaced, but as you already charged the battery externally, there must be another problem.
I found it difficult to attach the connector of my new battery, required a lot of pressure, and to arrange the battery cable such that it won't push up the connector. There was hardly room for the battery cable, as it was two or three millimeters longer & the wires quite stiff.
Click to expand...
Click to collapse
I will check the USB assembly just in case it might affect something. Better to be safe than sorry
What would be super useful would be a schematic/diagram, but I guess that there is no maintenance/service manual available anywhere is there?

Fugget about schematics etc.
The usb assy costs less than $10€,fortunately, but also contains the buttons and leds, which makes replacement a bit more complicated.