Non-metric or non-decimal money is referring to systems where the multiple tiers of money, like our cents and dollars, are seperated by amounts other than 10 or 100, like the old British system of 12 pence in a shilling and 20 shillings in a pound https://en.wikipedia.org/wiki/£sd
To be fair I think it is there as a backup for low temperature climates, the Lithium batteries wont charge at temps that low, but they still could have setup the lithium batteries as an emergency backup for all the 12v stuff.