Battery Substitute

[magatru]

Hi all,

Currently I'm working on project to replace the internal battery from PDA (iPAQ series 37xx and 38xx), because the original battery is very expensive so I'm looking for substitute from cellphone battery which have lower cost and have the same power (in type, Volt and close in mAh), everything work normaly until I power on the device, i'ts seem the battery drain so fast, can't last more than 1 hours.

original battery : 3,6V Li-Polymer 950-1200mAh
substitute battery: 3,6V Li-Ion    950mAh

1. If the case of low in mAh, why the same type for replacement didn't work well? (original battery for 37xx series is 950mAh)
2. how to measure the real mAh from the battery?
3. and last, did the procedure for substituting the battery will harm or affect the device?

Because I don't have electronic theory basic, don't know where i'ts wrong? :-[

Any help would be greatly appreciated,

 

[EdwardM]

Hi magatru

The first question I have to ask is: are you sure that the replacement L- Ion battery is fully charged? as within reason 950mAH is the same no matter which battery technology you use.  I've done a net search of PDA's and some specify that either L-Ion or L-Polymer can be used.

If the substitute starts fully charged and only gives 1 hour of life, does an original battery give full or the same length of time?

To measure mAH, you need to at least be able to measure current using a multimeter, ideally you should use a datalogger as the power consumed by the PDA will vary greatly during the discharge cycle.

Lastly, provided that both types of battery use the same connector scheme, there is no reason to harm the PDA.

Hope this helps

Ed

 

[magatru]

@EdwardM,

Thanks for the reply, honestly.... I followed the DIY tutorial from PDA forum to change old PDA internal battery with cheap and easy to find cellphone battery, and succesfully change the battery without problem (using flat ericsson battery  - T28-T39-R520 type and SE 610 with more power, yes ... you have to open the plastic case and use only the battery without the regulator inside because the iPAQ  did have regulator itself ).

Yes, I got the battery full charge ( from the iPAQ,  tap at Start>Setting> System>Power it show charging procedure until full at 100% and the led stop blinking) also I did the common first time charger when it's takes more than 8 hours to left the battery at charger position even if the led stop blinking).

Because the battery life will vary considerably depending on the backlight setting (it's the worse part which consume a lot of power) I try to ajust the setting in the powersave mode and hope it can be give more living to the battery, AFAIK the original battery with this setting can give you more than 1,5 hours of constant used.

For more testing I left the PDA uncharged for almost 2 days, and I found it only left 25% of battery capacity, when I turn it on its show blink at the backlight then dead. This is the software protection to maintain the data if the battery capacity reaches the critical level to power off the device.

1. Is the battery has fake label in capacity?
2. Can you describe more detail in measure current - mAh from the battery using multimeter?
3. What is datalogger?

Sorry  .... if I have too many question, 


regards,

 

[EdwardM]

Hi magatru

from the sound of it, the replacement battery is probably faulty and is not charging fully even if the PDA says that it is charged.

To answer your questions:

1. There are counterfeit goods around, I don't know.  If you got the battery from a reputable source then it was probably OK

2.  mAh is a measure of the capacity of a battery to deliver current for some length of time.  In your case, 950mAh means that the battery should deliver 950mA for 1 hour or 95mA for 10 hours or 9.5mA for 100 hours. 

To measure the fully charged battery capacity you need to do two things, first you need to connect it to a circuit which will measure current and voltage at the same time and then connect a resistor which will cause the battery to discharge. A circuit is shown below.  The idea is to make a note of current and voltage at fixed time intervals and then produce a graph from which is deduced the mAh figure, this is a tedious process and should really only be undertaken if all else fails. 

3.  The measurement I've just described can be done automatically by a datalogger, this is a machine which at fixed intervals, say every 10 seconds, will record voltage and current for you instead of you writing it down. 

The PDA forum you mentioned, perhaps you could post details of the DIY tutorial.

Best of Luck

Ed

View attachment 37018

 

[magatru]

@EdwardM,

Hmmmm, the first thing come in my mind is I got the fake battery, the labels didn't prove it's should be. Maybe I should take your advice to buy it from reputable source  ;D

The DIY tutorial I describe above can find at http://en.pdamobiz.com/en/forum/forum_posts.asp?TID=142&PN=1&TPN=1
and I have post the same question too  ;D

From your explanation it's need more than brave heart to open the case and change / subtituting the battery ;D

Thank you ... very very very much,


best regards,

magatru

 

[magatru]

Sory wrong address  ;D ;D

the topic is here http://en.pdamobiz.com/en/forum/forum_posts.asp?TID=225&PN=1l

best regards,

 

[EdwardM]

Hi magatru

Good site!, I may need to use it myself soon

Best of Luck

Ed