Battery or recharge circuit problem - C860

[Miami_Bob]

Aussie -

 << the AC/DC charger can then recharge the battery, and the LED light will be on continuously. When the battery has charged, then no further current can flow through to the battery, and the LED blinks intermittently. >>

This popped up from my back brain just a bit ago.

Do you mean that when your Z is fully charged in normal use, the charging LED *blinks*? The LED on my C860 goes OUT once fully charged. The only time that I have ever seen it -blink- is on AC with no battery installed.

If yours blinks when charged full, that may mean something significant also.

[gromituk]

...the multimeter shows that the battery charges to 4.2v quite quickly with my 5.1v, 2.5amp AC>DC charger.

I would be careful charging the battery with such a high current - you may well shorten its life considerably.

Very interesting deductions going on on this thread!

[ThC]

I think it's one of the worst days of my life ...
yesterday when unplugging my charger , I accidentaly inversed the polarity on it (damn third party multipurpose charger) and plugged it in with inversed polarity for ... maybe half a second before relising the light weren't going on and unplugging it... Now the charging light is back when I plug it back wih good polarity but the battery don't seem to charge at all ... I think I've frown the charging circuit in my Z BUT do you think I should/could try this solution anyway ?
If someone experienced the same problem and had to send it back for repair ... how much did it cost ? is there a way to have it fixed by myself/someone else than sharp ?

[ThC]

Just followed the HOWTO... et voila.. seem to work well now, just used wifi a few minutes and recharged the battery to its initial state,will test more tomorrow ... so it seem the values got lost because of inversing polarity ...

edit : i got wrong and was dreaming too much ... it didn't worked and it won't charge anymore   ... if someoe could answer my second question plz (can I have it repaired by myself/someone else than sharp ?)

[cgrieves]

I'd love to be proved wrong, but I reckon there are two types of charging issue:

1) Those who have simply lost their charging parameters in flash memory.

2) Those who actually have a fried charging system.

I think we really need users with and without problems to post their voltage values from the service menu. If people with no charging problems are reading 2.8 volts with a fully charged battery then there's hope.....


Incidentally, I don't know a lot about embedded systems, but it seems to me that if the service menu (which surely is just a program stored in flash memory) can adjust the charging parameters, surely we should be able to write an application that can modify the values outside of the service menu?

[Miami_Bob]

Have not seen this info mentioned on ZUG. Its important (IMHO) for anyone charging the Sharp EA-BL06 battery by alternative methods.


sbbloom69 posted on "The Zaurus Message Board Forum Index -> Hardware" in the thread "C700 - battery charge problem"

http://externe.net/zaurus/forum/viewtopic....fa3a29b6dc3b75f

----------------Begin--------------------------

 You must be very careful with the battery. It is not just a battery. I had a dead EA-BL06 (in my SL-5500) and decided to dissect. I then found a Li-IOn white paper from Panasonic that describes the batteries construction and operation.

 The EA-BL06 is actually a Li-Ion battery, a small circuit card with a voltage (or current, I'm not sure) regulator, an in-line fuse, and a thermistor imbeded down in the battery. Yes, all these components are on the small sliver-sized circuit board. The three battery terminals are actually large trace pads on this circuit board. The components are on the other side.

 The thermistor is a temperature variable resistor that can be read between the center terminal and the negative terminal. Its purpose is to control the charge current to the battery based on the battery temperature. That's how you can get a full charge in only few hours. The charge current is adjusted high enough to just prevent heat damage. Many laptop batteries have this too.
 

 BTW, I just took meter readings and here's what I got on a brand new, fully charged EA-BL06 battery:

 Voltage: from + to - terminals: 4.21 volts DC

 Resistance: from 7 to 12 kilo-ohms from the middle terminal to the negative terminal (depends on battery temp).

 Resistance from + to - doesn't make much sense on this battery, unless you have 0 volts. If you have 0 volts, the internal fused on the circuit card probabaly blew, and you will then get a very high resistance (100 Kohms to several Mohms). A multimeter in the "resistance" mode actually sends out a small voltage and performs Ohm's law (R=V/I) The meter "knows" the voltage and measures the current. Do the division and you know the resistance. A battery is putting out its own voltage (makes sense!), countering the resistance meter's voltage. Therefore, you can't really read the resistance on a "good" battery. Battery internal resistance can be determined with a bridge circuit, or by connecting a precision resistor and ammeter to the battery and solving the equivalent circuit analysys. You should still get about 7 to 12 Kohms from the thermistor (middle to negative terminal), the colder the battery is the higher the resistance.

 Hope this helps. It amazes me that a simple battery is not just a simple battery anymore. It does bum me out that the Zaurus wont' work at all without a functional battery (just the charger plugged in). I verified this with Sharp: No battery, no zaurus.

 I'm waiting on a BL-08 to do the mod and give my C700 twice the life. I'll post my results when I get it.
Stu
_________________
Stuart
======
SL-C700 (Dynamism, Sharp ROM), AmbiCom WLAN, 64MB Kingston SD card, RIDATA 256MB CF Card
SL-5500 Sharp Rom, SOCKET LP-E CF LAN, 64MB Kingston SD Card, Various 8, 16, 32MB CF Cards
-----------------End---------------------------

I was curious about the "Li-IOn white paper from Panasonic that describes the batteries construction and operation" mentioned & tracked it down to:

http://www.panasonic.com/industrial/batter...on_Charging.pdf

The paper is titled "OVERCHARGE/OVERDISCHARGE/OVERCURRENT SAFETY CIRCUITS" and dated Aug 2003.

One interesting & useful portion of the paper is the section titled "Battery Pack Block Diagram (Reference Example)"

"The diagram below shows a diagram of a lithium ion battery pack. The battery pack includes the batteries, the safety circuits, and thermistors."



I could not get the post to retain the formatting of a diagram here no matter what I did so will try to add it as an attachment.


"1. The Safety Circuits

1.1 The Controller IC

The controller IC measures the voltage for each cell (or for each parallel battery block) and shuts off a control switch to either prevent overcharging (if the voltage exceeds the specified voltage range) or to prevent overdischarging (if the voltage falls below the specified voltage range). Moreover, the voltage of the control switch is measured on both ends and in order to prevent overcurrent, both control switches are shut off if the voltage exceeds specifications.

1.2 The Control Switches

The control switches usually comprise FET structures, and they turn off the charge or discharge depending on the output of the controller IC.

1.3 The Temperature Fuse (Reference Materials)

If the control switches experience abnormal heating, this fuse cuts off the current (non-restoring).

 (NOTE THE "non-restoring"! -- M_B)  

2. The Thermistors

The thermistors are included in order to accurately measure the battery temperature within the lithium ion battery packs. The battery or charger measures the resistance value of the thermistor between the Tterminal and the negative terminal and during the charging process, controls the charge current along with controlling until the charge is terminated.


 Functions and Performance Required in the Charger (Recommendations)

(1) Charge Voltage

The voltage between the charging terminals should be no more than 4.20 V (Set this at 4.20 V (max) after taking into account fluctuations in power supply voltages, temperature deviations, etc.).

(2) Charge Current

The reference charge current should be 0.7 CmA.

(3) Ambient Temperature of the Battery Pack During Charge

0°C to 45°C (Consult Panasonic if the battery pack is to be used outside of this temperature range).

(4) Low-Voltage Battery Pack Charge

When the voltage per cell is 2.9 V or less, charge using a charge current of 0.1 CmA or less.

(5) Termination of Charging

The system will determine that the battery is full by detecting the charge current. Stop charging once the current has reached 0.1 CmA to 0.07 CmA. Note that there will be some degree of variation for each individual battery.

(6) Charge Timer

A total charge timer and a charge completion timer should be included.

(7) Countermeasures for Battery Problems

Select an overvoltage guard in the power supply so that there will be no excessive voltage applied to the battery even if there is a problem with the power supply".

The paper also includes a detailed section titled "FLOWCHART FOR CHARGING LITHIUM ION BATTERY PACKS" which is highly informative but too complex to reproduce here.


A 2nd useful paper in this series is located at:

http://www.panasonic.com/industrial/batter...Precautions.pdf


None of the OEM lithium ion batteries listed at:

http://www.panasonic.com/industrial/batter...hion/index.html

have the form factor of the Sharp EA-BL06, BTW. They are of the "Cylindrical Type" or the "Prismatic Type - Aluminum Housing". So it appears likely that the EA-BL06 are assembled either by or for Sharp specifically.

[cgrieves]

I just checked my unit with a multimeter. The Sharp standalone charger puts out close to 5V with no battery inserted. My C860 puts out 2.4 volts across the same terminals. Either this voltage ties in with the voltage set in the battery adjustment section in the service menu (i.e. the voltage we're setting is in fact a charge voltage, not a battery voltage), or the charging system truly is fried and will never put out enough voltage to fully charge a battery.....

There may be a quick way to resolve whether there is a hardware or firmware issure here. Can someone with a C860 with a known-good charging circuit remove the battery, plug in the Sharp PSU, and measure the voltage between the terminals in the battery bay?

[Miami_Bob]

I just checked my unit with a multimeter. The Sharp standalone charger puts out close to 5V with no battery inserted. My C860 puts out 2.4 volts across the same terminals. Either this voltage ties in with the voltage set in the battery adjustment section in the service menu (i.e. the voltage we're setting is in fact a charge voltage, not a battery voltage), or the charging system truly is fried and will never put out enough voltage to fully charge a battery.....

There may be a quick way to resolve whether there is a hardware or firmware issure here. Can someone with a C860 with a known-good charging circuit remove the battery, plug in the Sharp PSU, and measure the voltage between the terminals in the battery bay?

cgrieves -

My C860 has been charging without any problems. I put it on AC then pulled the battery. The AC/charging LED went out as soon as I flipped the battery switch to Unlock.

The voltage (good digital multimeter) + to - at the C860 with the switch set to unlock was 0.556 V. When the switch was moved to Lock (still no battery) the AC/Charging LED began to flash & the voltage went up to 2.386 V.

I do not have a stand alone charger so can't give any info on that.

I'm curious as to the voltages put out under the D+M menus with & without charging enabled, but I a bit chicken of possibly frosting my charging circuits by turning charging on in D+M without a battery in place. I think that I'll leave THAT test up to someone else.

But your 2.4 V looks like an acceptable value based on my own working system.

[Miami_Bob]

cgrieves -

The Panasonic charging flow chart starts with a battery pack insertion check. I suspect this is done by checking the thermistor - fuze loop from the (-) to the (T) terminals. Possibly combined with the Lock/Unlock switch?

If no battery pack is detected, the chart loops back to the top & checks again.

If a battery pack is detected (entry point A), it updates & checks a charge total time value T1. If T1 is > 720 min the loop abends with a timeout error. Otherwise, the battery temp is checked and tested to be between an upper & lower max.

If the battery temperature is not in the correct range, the system waits then loops back to (A). If the temp is OK, then  "Is voltage check 1 (no load) higher than the charge completion voltage? (4.2 V)".

If > 4.2 V the loop abends with an Overcharge error. In < 4.2 V the next check is "OCV>2.9V". If YES, the system goes into 0.7 CmA charge mode. If NO, into 0.1 CmA charge mode.

In  0.1 CmA charge mode the system either senses the battery voltage > 3V and loops to (A), or a recharge timer causes a loop either to (A) or to the Timeout error.

In 0.7 CmA charge mode, the charging currernt is monitored and compare to two preset values. Based on these measurements and a timer, the system can loop back to (A), timeout or succesfully complete charging.

The voltages mentioned in the paper are 4.2V & 2.9V in the flow chart and the following

1. The Overcharge Safety Function

The charge stops when the voltage per cell rises above 4.30 ± 0.05 V.
The charge restarts when the voltage per cell falls below 4.00 ± 0.15 V.

2. The Overdischarge Safety Function

The discharge stops when the voltage per cell falls below 2.3 ± 0.1 V.
The discharge restarts when the voltage per cell rises above 3.0 ± 0.15 V.


For what its worth. It still doesn't make much sense to me yet.

[cgrieves]

That cycle does kind of make sense. I just used a faster responding voltmeter on my Sharp standalone charger and the voltage between the terminals ramps rapidly, as if the charger is searching for a battery using the logic loop you describe. However the same two terminals in my C860 do not do this. Whether this is due to the componentry being fried or the flash settings limiting the voltage is, I guess, impossible to tell...

I am going to pull my standalone charger apart tonight, has anyone got any detailed pictures of the inside of a C860? I know it's unlikely but if there's a common component between the PDA and the charger we may at least know which part is responsible, and how much of a nightmare it would be to replace.

[Miami_Bob]

That cycle does kind of make sense. I just used a faster responding voltmeter on my Sharp standalone charger and the voltage between the terminals ramps rapidly, as if the charger is searching for a battery using the logic loop you describe. However the same two terminals in my C860 do not do this. Whether this is due to the componentry being fried or the flash settings limiting the voltage is, I guess, impossible to tell...

Does your stand alone charger have 3 terminals like the C860 & battery? If so, you might want to put a resistor between the middle (T) terminal & the (-) of the charger to simulate a battery thermistor (ie - tell it a battery is there). I seem to recall 17k ohm as one of the values in another post of the other related thread here.

Of course, if the stand alone charger is measuring the (+) to (-) voltage &/or the charging current, it probably won't be fooled for long, but the voltage output behavior may give some more useable data.

If I understand the Panasonic paper correctly, the flow chart loops are executed by the external charging hardware while the Overcharge & Overdischarge values seem to refer to the safety control circuits internal to the battery pack itself.

It would be really nice to be able to place a "break out box" between the C860 battery bay terminals and the battery so as to be able to track the charging voltage & current from the C860 interal circuitry. Not sure if this could be done without considerable difficulty, though.

[seva]

Any updates on the possibly fried charging circuitry, has anyone tried replacing it?

Also, https://www.oesf.org/forums/index.php?showtopic=11539

[edi800]

Any updates on the possibly fried charging circuitry, has anyone tried replacing it?

I will try this or nexxt week to fix my SL-C760, so stay tuned.

I have the same problem - lower battery charging voltage, so that battery is not being charged anymore. Caused that by inverting polarization on the DC adapter :-(

I think also that probably those small capacitors on the Z mobo are fried, so they need to be replaced. I found that such small capacitors can be found on some PC mainboards, so the only problem that remains is to find a solder gun capable of soldering such tiny elements :-)

[stuffman]

Well, my 860 is not charging, but for a different reason entirely. The cute little power adaptor that came with it seems to only want to put out about 2.1vdc to the Z (it's rated at 5vdc output). I can probably go to Rat Shack and get an adaptor to replace it, but I'm quite fond of its easy portability. Has anyone taken one of these apart? It seems like it's just snaped/glued together, and shouldn't be too hard, but it feels like I'm going to break it before it opens. Any help would be greatly appreciated.

[cgrieves]

Sorry to bring an old thread back from the dead, but it seem this is the only source of info for Cx60 users with truly fried charger circuitry....

Has anyone managed to repair the faulty charging circuit? Alternatively has anyone outside of Japan had their units repiared for a reasonable price?

I'd love to make my C860 usable again so I can ditch this 'orrible IPAQ!
Cheers!