Constant Cruise

Batteries under the bed???!!! In a fully ventilated compartment as per BSS? If a battery compartment is ventilated, as per my understanding of said regs, then not impossible for inside ambient temperature to be very close to outside ambient, which could be tricky in winter. Ventilation essential for lithiums as they can get hot and if you're au fait with warranties then you'll know the terms. Ventilation essential not just for gassing, lithiums don't, but cooling of the batteries. And further are your insurers happy with batteries under the bed if not in fully ventilated compartment as per BSS? Strikes me you are pushing it a bit, still it's your boat.

Have been following the Lithiums v LA argument for a while; unfortunately most if not all folks overlook the paperwork. Not the technical specs per se, which are interesting enough, but it is the warranty folks should read. The warranty is pretty specific about the range of temperatures it covers. Lithium batteries are claimed to be the answer (for now ... I am intrigued about the application of hydrogen fuel cells in that French boat visiting the Thames ... narrowboat next?) for storage batteries and in specific circumstances they are truly excellent, but not necessarily in a temperate climate as we have in the UK. And for those folks not in UK my observations may not necessarily apply to their locale. The warranty virtually warns against their usage in in some climates (my interpretation of course) because you should avoid charging them at high rates at subzero temperatures. Doing so can allow lithium to permanently plate one of the electrodes (Google for tech aspects, it is fairly involved. You will find details also on such arcana as Battery Management Systems ... extremely important in lithium battery chemistry). The warranty will not cover you for this type of damage. Plus the upper limit for usage is described as 43C. Exceed this and you're on your own if seems. Nobody will forget that a year of so ago we experienced winter temperatures of neg 14C in rural areas. So if your lithiums got below freezing then unless the BMS took this into consideration you risked over charging the batteries and their consequent destruction. Subzero charging rates are measured in milliamps, which rather defeats the claim of rapid charging. There are some lithium batteries that incorporate an inbuilt battery heater, which is one solution, but it takes time to heat up the battery to a "safe" temperature for charging at a higher current. You will note this again defeats the claims of rapid charging. And you may think that a lithium battery is getting more packed with BMS electronics and now heating equipment. Does this complexity imply less reliable operation? I don't know and certainly don't want to find out when I have flat batteries on an iced up canal and not enough current to run my Webasto and circulating pump. Of course I can fire up my Morso but I don't have a backboiler. Please note too that discharging a lithium battery at subzero temperatures is not a problem ... until it goes flat. These issues would put me off lithium batteries completely. In light of this I have slightly altered the direct of this topic, so apologies up front. I would suggest therefore researching the lead carbon technology. Lead carbon technology is not new by any means but one plus is that by using carbon in the "electrode chemistry" sulphation is very much reduced. By reducing the action of sulphation, so to speak, this results in an extended life. I gather too that lead carbon batteries can be charged at higher rates in less time cf ordinary lead acid batteries. Not quite a match for lithiums but not far off. As above Google is your friend. What might be of interest too is there are a lot of papers published by, for example, Ford Motors and American universities, on the topic of lithium batteries regarding their application in the "real world". By "lithium" I refer specifically to the LiFePo types. Lithium has been combined with many other elements to produce many variations of batteries for specific applications. IE the lithium battery in your cellphone is an entirely different type of lithium battery we would use to replace a lead acid battery. So, to summarise, quoting the technical aspects of a lithium battery is largely academic, it's the ambient temperature in which they are used is what you want to worry about. In my opinion.