China makers offer a wide selection that is compatible with units from industry giants. Many have a capacity of 4,400 and 5,200mAh but 6,000 to 7,200mAh versions are also available. Six-cell Li-ion types dominate.

For HP DV4

Daxpoo Tech Co. Ltd
The DV4 model from Daxpoo has a voltage of 10.8V and a 4,400mAh capacity. The six-cell Li-ion laptop battery comes in black and is designed for HP DV4 computers. It is packed in a carton with anti-static bag and sponge cushioning. Warranty is one year.

ThinkPad series

Dongguan Greenway Battery Co. Ltd
Dongguan Greenway's model IBM ThinkPad R61I 10.8V Li-ion laptop battery comes with 4,400mAh and 6,000mAh capacity. It is compatible with the ThinkPad R61, R61i, R61w, R61p, R61u, R400 and T400 series, and Lenovo laptops. The unit is available in black and measures 224.2x76.5x32.8mm.

Fits Sony VGP-BPS13

Dongguan Greenway Battery Co. Ltd
Available in black-and-silver, the SO BPS13 model from Dongguan Greenway serves as a replacement battery for Sony VGP-BPS13 and other Sony laptops. The 11.1V Li-ion unit has a capacity of 4,400mAh and weighs 309.7g. Product dimensions are 204.2x47.1x20.6mm.

9 cells, 7,200mAh

Dongguan Zhaoshun Electronics Technology Co. Ltd
Dongguan Zhaoshun offers the 9-cell AC ONE(H)-Black-1-1-1-1-1-1-1 model that suits Acer Aspire One units. The CE-marked rechargeable Li-ion battery has a voltage of 11.1V and a 7,200mAh capacity. It is available in black-blue-white and weighs 458g.

Suits ASUS laptops

Wecanpower Technology Co. Ltd
The model K72 6-cell Li-ion laptop battery from Wecanpower is compatible with ASUS A72, K72, N73, N71, K73 and X77 series. The standard voltage and capacity are 11.1V and 5,200mAh but 10.8V 4,400mAh versions are available. The unit has a life span of 500 to 800 cycles and a backup time of 3 to 4 hours. The model meets CE, FCC, UL, TÜV and MSDS requirements. Warranty is 12 months.

Lasts 500 to 800 cycles

Wecanpower Technology Co. Ltd
Wecanpower's selection also includes the BPS26 model that fits Sony VGP-BPS26, VGP-BPS26A and VGP-BPL26 units. It suits the Sony VIAO C, CA and CB series as well. The 6-cell 11.1V 5,200mAh Li-ion laptop battery is good for 500 to 800 cycles and has a backup time of 3 to 4 hours. The unit adheres to CE, FCC, UL and MSDS standards, and comes with a 1-year warranty.