Healthgrades Editorial Staff. Tingling in both feet can have a number of causes, including an injury, sitting in one position for a long period of time, or a circulation problem that impairs blood flow to the feet. Tingling in both feet can also be caused by nerve damage from extreme heat or cold or from toxic substances.
A lopped-off finger will still have a place on your hand for about 12 hours after amputation if not refrigerated, but a full limb like an arm or leg -- left at room temperature -- must be reattached within six to 12 hours, due to rapid death of muscle tissue.
As an example: Say you have a 100 amp-hour battery that has been discharged by roughly 50 percent. You would therefore need to replace 50 amp-hours. Using a 10-amp charger, take 50 amp-hours and divide by 90% of 10 amps (or 9 amps) = an approximate 5.6 hour recharge time. A deeply discharged battery deviates a bit from this formula, requiring more time per amp-hour to be replaced.