This one for Lithium / LiFePO4 batteries -

 

L Bob: I have a twin power Lithium in my RK,almost 4 yrs old. I got in touch with Optimate as soon as I bought the battery. They recommended the TM-291 which is their 5 amp model. I wouldn’t go with a different brand or a lower powered model.

 

The TM-291 is Optimates top of the line model that is designed to do more than just maintain a battery - it also has a recovery mode
that is necessary should you somehow run your lithium battery into shutdown. Of course that feature isn't free - about $45 more - but
probably worth it considering it can also charge at a higher 5 amp level.
Here -