Temperature, page-2

Hi.

The gist is that the temperature operating limits are defined in terms of electrolyte fluid temperature and that this fluid has a high thermal mass (holds a given temperature quite well for long periods), and that as a result the outside air temperature can be well outside of the fluid temperature range for extended periods without issue.

In terms of fluid operating temperature, the current limits (which may be widened in the future) are:

Charging from 10C, Discharging from 15C, and running from there up to a maximum of 50C. Beyond those limits the unit blocks charging and/or discharging to self-protect (and is not damaged).

Peak efficiency is in the mid 20's Celsius, and the onboard fan and radiator structure build in under the stack are used to access ambient air to raise or lower the fluid temperature when there is a differential to the outside air temperature that allows this to happen. In other words, the system actively 'controls' for that optimal temperature band and generally manages to achieve it very well.

We have operated batteries for an extended period (and continue to do so) on sites where the outside ambient temperature is routinely well below 10C (indeed where it routinely below zero in winter) without issue, on sites where the batteries are continuously operating (which is also the strong point of our battery in terms of application suitability).

As a natural by-product of operating, all batteries (and ours is no exception) get warm - in effect our battery keeps itself work by the act of operating normally. That includes for extended idle periods where the pumps have stopped - it still takes ages for the fluid temperature to drop - especially when inside an enclosure. The fan/radiator are then used to limit maximum temperatures (as already noted).

The only issue we have found in practice is 'bootstrap' from 'cold' - i.e. for a site where the batteries have been shutdown for an extended period and where the site is being recommissioned (or indeed commissioned for the first time) in a very cold place. In that case it can need one to wait for the ambient temp to rise above 10C or the use of a cabinet heater to get it going (which can be as simple as putting a small heater near the fan air inlet to the battery, so our on-board control system can detect that higher temperature and will automatically run the pumps and fan to draw the warm air in and raise the fluid operating temperature).

I will note that the use of cabinet heaters is a routine, common, and low cost thing that gets put into telco equipment and/or battery cabinets all the time - lots of batteries have specific operating ranges in terms of temperature (most don't like running as hot as ours do, though, and can need cooling - something we generally don't require).

I'll also note that shutting down other sorts of batteries for an extended period generally leads to them becoming damaged - but ours don't mind being shut down for extended periods at all. No risk of damage from total discharge accrues for our product from running down completely or from being put on a shelf for an extended period and just 'left there'.

All that said, one reason why our battery really shines in hot countries is that high ambient temperature has a strong impact on the longevity/lifetime of lead acid batteries (and doesn't impact our lifetime - our battery thrives in warm places).