Recharging: Your HP adapter will recharge the battery pack many times. A fully charged battery pack should last for about 10 hours of continuous use. The HP adapter/charger will recharge the battery pack faster if you turn off the display, yet will also charge it with the display on. These batteries will completely recharge through your plugged in HP adapter in about 6 hours, depending on the prior calculator usage.
The 2800 Bonai battery pack is an excellent battery pack. Eventhough it is labeled at 2800, it functions as any 3000 battery pack I sell. The Bonai cells are mor expensive and hold their charge very well.
Battery Storage: Please protect your beautiful HP calculator! All new rechargeable battery packs will eventually leak a corrosive acid that may harm your calculator. However, as a precaution, write on the label the purchase date plus three years after installing it for the first time. Conservatively replace after three years (should last much longer). If you are not using the calculator for a long time, please consider removing the battery and place it in a sealed plastic bag. These devices are just too awesome to risk any potential damage.
Shipping: Shipping costs are listed below. For multiple battery pack purchases contact me for actual shipping costs. I will refund your extra shipping charges and only charge you actual shipping costs. BTW, 93.9% of my sales are mailed in one day.
Also check my other HP calculator battery packs for sale especially the HPClassic HP-35, 45, 55, 65, 67 calculators and for the larger HP-Topcat HP 95-97 calculators. Waterhosko is also advertised on the HP Calculator Museum website.