As to battery choice it is worth looking at those with absorbent glass mat technology for performance and longevity. Not only can the battery be positioned in any orientation i.e. on it’s side it contains so little acid that Postman Pat delivered mine. I also understand that they are used extensively in military vehicles. When it came time to replace the battery on my SS I repositioned the fuses which enabled me to increase the battery’s capacity from 12 to 18 amp/hours. That was 10 years ago and still going strong. At the same time I didn’t replace the oem cables from battery to solenoid to starter plus earth but ran heavier duty ones alongside so belt and braces. Have a look at these guys. https://www.powervamp.com/news/selecting-the-correct-racing-battery/
I’ve been using Motorbatt AGM batteries for years on my bikes, they hold their charge unbelievably well, I’ve got one that’s been lain on it’s side to fit under the tail hump on my Hailwood lookalike Honda for at least four years and even though I only charge it or run the bike once in a blue moon it always reads around 13v, so I’ll second that for AGM’s
I wont get into the really boring bit about Lithium batteries, I can bang on for hours if I do...but there are Lithium Ion and there are Lithium Iron (amongst other Lithium) types. Lithium Iron Phosphate to be exact. LiFePO4 Lithium Ion is the catchall for all the sub types really. The other Lithium types tend to go in Laptops and stuff like that. Lithiums are lightweight and will recharge from flat in minutes. They will not be killed by going flat BUT they need the correct type of charger to maintain them, and they do go flat quite quickly if not on a maintenance charger if there is any sort of current draw from the bike. If you use the wrong charger, they can catch fire - and you do not want to be around a lithium battery fire. There are different qualities same as with lead acid. Some good, some great, some poor. Old adage of you get what you pay for applies. I had one on my ZRX until I sold the bike last week and it was great I kept it charged up though. I used a Shido battery) which IS one of the better brands, but be warned if you have an alarm, a sat nav or anything at all connected up - they go flat very quickly if the bike is not being used. A week/10 days can be enough to flatten it to a level where you need to charge the batt (5 or 10 minutes can be enough sometimes) - to start the bike. Yuasa or GS ( different companies aftermarket, same company OEM) lead acid batteries are two of the very few manufacturers that ONLY use new lead in their manufacture. That makes for more stamina and they hold charge longer. They last longer as well, provided you look after them. The others use recycled lead which has impurities and affects the quality and life of the battery...you pays your money and takes your choices AGM - Absorbent Glass Mat, is a fancy term but basically all MF batteries have them anyway. They shouldn't leak, but can leak. Some manufacturers boast about AGM like it is a fancy technology, but it isn't really. MF = Maintenance Free (but they aren't, they still need charging lol) If you have the AGM/MF type where the battery is filled from an acid pack and then sealed by the seller or user..well unless you do that job perfectly, they can and do leak. I have seen very expensive bikes ruined by leaks from that type because they were capped before the chemical reaction has finished in the battery which allows the mat to soak up the acid (they need about an hour before being capped and charged), and of course they then can weep acid. The types that are factory sealed, have a shorter shelf life in the shops but wont leak. Both still need maintenance charging to keep 'em at their best
