[Captivate Accessories] slvr00gt:
SUMMARY:

china1800, jindian1900 and andida1850 sold on ebay is a SCAM. The real capacity of these batteries is less then 1300mAH. Instead, for the same $10 on ebay you can get two spare batteries at roughly the same capacity and a charger. Capacity of newly available on ebay extended size batteries for captivate (cptvt3500_1) is also overblown, but for $10 a pop you get a battery with 2100mAH worth of juice. It is 40% improvement over stock

TERMS:

( See picture of the battery inside LiIonTester.zip file. Each tag below has corresponding picture file inside LiIonTester.zip)

1) china1800_1 – Battery advertised on ebay as 1800mAH:

http://cgi.ebay.com/1800mAh-Samsung-...item230c6fa877

2) china1500_1 - Battery sold on ebay and advertised as 1500mAH

http://cgi.ebay.com/1500mAh-NEW-BAT...974810?pt=PDA_Accessories&hash=item483cef829a

3) china1500_2 - Another battery sold on ebay and advertised as 1500mAH. My coworker gave me two to test. Both performed similarly

http://cgi.ebay.com/2x-1500mAh-Batt...086?pt=LH_DefaultDomain_0&hash=item4aa7cc8bb6

4) china1500_3 - Another battery sold on ebay and advertised as 1500mAH

http://cgi.ebay.com/2pcs-1500mAh-Ba...037707?pt=PDA_Accessories&hash=item2a0c4d960b

5) jindian1900_1 - Jin Dian battery sold on ebay and advertised as 1900mAH

http://cgi.ebay.com/1900mAH-Battery...972297?pt=PDA_Accessories&hash=item2a0cb76649

6) andida1850_1 - Battery advertised as 1850mAH sold by Obostore

http://www.obostore.com/1850mah-andida-spare-battery-for-samsung-galaxy-s-p-315.html

7) samsung1500_1 – OEM Samsung battery came with my phone ( after 6 months of use )

8) china3500_1 - Extended size I9000 battery ( Doesn't fit Samsung Captivate

http://cgi.ebay.com/NEW-3500Mah-EXT...669711?pt=PDA_Accessories&hash=item56423fdf8f

9) cptvt3500_1 - Extended size battery for Samsung Captivate requires new battery door

http://cgi.ebay.com/High-extended-3...774?pt=LH_DefaultDomain_0&hash=item3366c99fce

10) cstm2600_1 - Custom battery I fabricated myself from two highest performing standard size batteries in my arsenal: china1500_1 and andida1850_1. See "custom_battery" folder inside LiIonTester.zip for pictures and DIY guide for the build

TEST RESULTS:

Capacity(10oHM) column is what you care about the most

See “more detail” below to know how 10oHM and 50oHM loads effect the test.

See LiIonTester.zip for all test data

TEST SETUP:

The batteries were tested with special circuit outside the phone. This is a true battery capacity test. Results are not skewed by the installed custom ROM, overclocking, varies apps and interfaces that can be on, usage pattern or out of whack battery stats of the phone.

Li-Ion batteries operate between 2900mV and 4200mV. 4200mV is fully charged and 2900mV is fully drained. Battery tester works within the normal operating range.

The setup consists of the discharge circuit, microcontroller board with the potentiometers(voltage meters) and LCD. Discharge circuit is just a power resister wired across the battery and power FET( transistor) turns the circuit on and off. Transistor is controlled by microcontroller that monitors the voltage drop, calculates the current and controls the test. Test stops when voltage drops to 2900mV.

See my rig's schematic and pics in the attachment below

MORE DETAIL:

samsung1500_1 after 6 months of use still put out 1426mAH in my test environment. china1800_1 puts out only 1275mAH after 1 month of use. Li-Ion battery real world capacity depends slightly on the rate of discharge. The faster the discharge, the lower the effective capacity. In my tester circuit the discharge rate is 370mA per hour. It takes roughly 4 hours to drain the batteries. This is within the spec, but on the higher side. One of my co-workers suggested that cheap chinese batteries might actually have the same chemical capacity, but due to sub-par manufacturing process, internal resistance is more negatively effected by the higher discharge rate then higher quality Samsung OEMs. To check out this theory, swapped 10oHM resistor for 50oHM. This change decreased the current to ~74mA. It improved achievable capacity, but only marginally. Improvement was within my earlier expectations.

Cycling of the new battery doesn't change capacity, but it does effect phone’s circuitry that estimates the charge. To the end user, it appears that battery improves over time. It really doesn't. Estimators within the device get smarter as they learn the properties of the battery installed:

http://batteryuniversity.com/learn/article/is_lithium_ion_the_ideal_battery

china1500_1 put out 1323mAH, but it was only advertised at 1500mAH and sold for pennies, so I am not complaining. The one weird problem I ran in with china1500_1 was its voltage unexpected collapse. During drain cycle voltage went down slowly to 2800mV and then precipitously dropped to zero and stayed there. Other two batteries, drained normally down to 2700mV and after the load was removed voltage went right back above 3000mV. It turns out china1500_1 has battery overcharge/undercharge protection circuit that shuts itself off at 2800mV. This observation was the part of the reason for minimum voltage change to 2900mV.

UPDATE: 04/17/2010

* Added DIY guide on how to build custom extended size battery from two individual standard size batteries. See "custom_battery" folder inside LiIonTester.zip

UPDATE: 04/12/2010

* Build & tested my own extended size battery. See "custom_battery" folder inside LiIonTester.zip for more pictures from the build

* Tested I9000 extended size battery

* Tested Newly available Captivate Extended Size battery

UPDATE: 02/14/2010

* Tested Andida 1850mah battery

* Included CuriousTech test results in LiIoinTester.zip. CuriousTech tested Original battery, Mugen and Andida using RC charger/discharger. His results are not apple to apple comparison with mine, but very useful when you compare it to each other.

UPDATE: 01/21/2010

* Tested Jin Dian 1900mah battery

* Tested another 1500mah battery advertised as G7

* Andida 1850mAH battery is in the mail.

http://www.obostore.com/1850mah-andida-spare-battery-for-samsung-galaxy-s-p-315.html

UPDATE: 01/15/2010

* Tested another 1500mAH battery. My co-worker bought and gave it to me to run the test.

* Upped test minimum voltage by 200mV to 2900mV to be on the safe side. Remaining battery capacity below 2900mV is only 2mAH. This residual capacity is consistent among different batteries so it should not skew the results

* Added slow discharge rate test to show capacity variation range