The battery in Icon HD Net Ready allows for up to 5-7 hours of diving time, with the actual duration strongly dependent on water temperature and usage of the high intensity on the back light. When diving a lot, as on a live-aboard, we recommend charging Icon HD Net Ready every night, like you would for a smart phone.
Icon HD Net Ready however uses up battery power also when not diving, at the rate of approx 5-6%/day. This means that the battery will go from full to empty in about two weeks without doing a single dive. This is due to the fact that Icon constantly monitors the environment, checking for ambient pressure every 20 seconds in order a) to start diving in case a diver jumped into the water without turning on Icon and b) to always have the correct reference pressure at the surface (autozero) in order to be accurate also in presence of altitude changes or barometric changes. Additionally, even in standby Icon must always be ready to receive RF (radio frequency) messages.
The standby battery consumption is quite higher in Icon HD Net Ready than it used to be on the original Icon HD without hoseless tank data integration. Aside for the energy needed to be ready for RF commands in Icon HD Net Ready, this is due to the fact that, while in Icon HD we were able to use stabilizers on the printed circuit board which were very efficient, for Icon HD Net Ready we had to use a different kind of stabilizers that unfortunately are less efficient. The switch to these stabilizers was necessary because of the high electromagnetic noise generated by the original and efficient stabilizers, which interfered with the ability to exchange information via the RF communication. The new but less efficient stabilizers are very quiet in terms of electromagnetic noise, and hence allow the communication to function, but unfortunately at the cost of a higher battery consumption. The problem of electromagnetic noise in Icon HD Net Ready is magnified by the fact that the color display itself generates significant EM noise. In other words, with all the technology packed in this instrument, it is unavoidable to have a limitation somewhere. An iPhone after all is much more likely ot be attached to a power outlet than a standard cell phone.
All this means that, even if you are not diving with Icon HD Net Ready, the battery will be empty within approx 2 weeks. If you haven't dived for 2 or 3 days, you should always recharge Icon HD Net Ready prior to a new dive. It does not hurt the computer to be left on the charger for extended periods of time, as it disconnects itself once it reaches full charge and then reconnects when the power drops by a few percent. An alternative for people with long periods of inactivity in diving is to let the battery run down and then recharge it prior to diving. Even if the battery is left empty for a few months, it does not get damaged by this and you are not going to lose any logbook data. You will however lose the correct date and time, so after charging it prior to a dive, it is necessary to set the date and time (this can be done in one click with Dive Organizer). When charging Icon HD Net Ready after a very long time of inactivity, we suggest to leave it on the charger overnight, or at least for 7 hours, to ensure a full charge.