my tp600e only charges to 42%

[mcpl@]

i have recently brought a tp600e without battery. i brought a battery from ebay (a new one from laptop auctions) when i first charged it it charged to 98% but the second time it only charged to 42% and it will only charge to 42% have tried discharging (using the looptest) but it still refuses to fully charge. HELP

thanx in advance for any help