So, if you had to recommend (based on your experiences and knowledge)...would it be appropriate to keep a lithium battery connected to a battery tender, and with the battery placed in the motorcycle?.....or would it perhaps be safer to maintain The battery icharging but inside a metal cube?….
My question is not to generate a controversy. because I already know that there are users who have been using lithium batteries in their motorcycles for many years, connected to a battery maintainer……But I would like to know the opinion of an expert in catastrophic situations.
Obviously the photo is for a tool battery, which I'm not too worried about, I just have the can there anyway from using it to charge the e-bike. That's the battery I'm most cautious about.
First off, (at least the) Battery Tender brand chargers use very low rates of charge and don't charge LiB batteries to their max so they minimize stress.
Second, all of the motorcycle batteries I'm aware of are the safest chemistry, LiFePo4 (LFP) which is very hard to get to burn. It is possible, just more difficult and generally requires physical damage or external heat from something else already hot. Or over-charging (charger failure), a battery already damaged, such as by repeated cold charging or over-discharge. The reason is there's no cobalt and the iron-oxide bond is stronger than the cobalt-oxide bond.
Here's a crude test to show that even though it is already discharged, LiFePo4 can burn (still won't explode). While yes he used a massive steel bar to puncture it, realize the same can happen if a pebble gets between the battery and case and the glowing red-hot at first which could ignite anything flammable coming in contact. The generation of smoke doesn't last long in LFP but can be both flammable and toxic.
So to your question and while I know a lot of people who leave their motorcycle battery on a tender all the time, it its not what I do. In winter when I think I can occasionally get to ride I'll connect it for a day then leave it off for a week or two or three till I think of it again because the Guzzi has an alarm and clock circuit that provides a
very slow drain. If the weather looks bad for a longer time, the best thing you can do is simply disconnect one of the battery connections because lithium batteries effectively don't self-discharge over very long (months) of time.