hi,
Any idea what temperature the SkyFi3 is rated down to, also should it be thermally insulated at all when really cold ( e.g. <5C)? Asking as went flat relatively quickly the other night (~4c), though I didn't charge fully before went out, hence may have been me not charging up enough. regs Jamie
Jamie,
I'm not aware that we have explicit temperature ratings. The SkyFi 3 has a lithium ion battery in it. They will have reduced capacity at low temperatures. Here is what "Battery University" has to say:
Lithium-ion works within the discharge temperature limits of -20°C to 60°C (-4°F to 140°F). The performance is temperature based, meaning that the rate capability at or below -20°C is reduced due to the increased impedance of the electrolyte. Discharging at low temperatures does not harm the battery. Lithium-ion may be used down to -30°C (-22°F) with acceptable results. Larger packs will be necessary to compensate for the reduced capacity at these temperatures.
Also, from Wikipedia:
Charging temperature limits for Li-ion are stricter than the operating limits. Lithium-ion chemistry performs well at elevated temperatures but prolonged exposure to heat reduces battery life.
Li‑ion batteries offer good charging performance at cooler temperatures and may even allow 'fast-charging' within a temperature range of 5 to 45 °C (41 to 113 °F).[84][better source needed] Charging should be performed within this temperature range. At temperatures from 0 to 5 °C charging is possible, but the charge current should be reduced. During a low-temperature charge the slight temperature rise above ambient due to the internal cell resistance is beneficial. High temperatures during charging may lead to battery degradation and charging at temperatures above 45 °C will degrade battery performance, whereas at lower temperatures the internal resistance of the battery may increase, resulting in slower charging and thus longer charging times.[84][better source needed]
Consumer-grade lithium-ion batteries should not be charged at temperatures below 0 °C (32 °F). Although a battery pack may appear to be charging normally, electroplating of metallic lithium can occur at the negative electrode during a subfreezing charge, and may not be removable even by repeated cycling. Most devices equipped with Li-ion batteries do not allow charging outside of 0–45 °C for safety reasons, except for mobile phones that may allow some degree of charging when they detect an emergency call in progress.[85]
Thanks Bill, answered what I needed - dont need to wrap the unit up then - more robust than my phone!