Using anything other than the recommended charger you will damage the battery!

Have Lithium batteries in all my bikes. And a bunch of customer bikes. A few things will kill them. Overcharging, letting them get completely flat, and using a charger with a 'desulphite' cycle, such as the one found on some Optimate chargers.
Had some long chats with the folks at Shorai and Battery Tender.
The early Shorais needed their charger, the later ones don't. In fact, if you have a Shorai that is almost flat, they told me to but it on a conventional charger first.
Shorai also said that the early Battery Tenders had too low a voltage level in the maintenance mode to keep their batteries charged. Later (last 10+ years) have a slightly higher maintenance voltage level and work well on Lithium batteries. The lithium batteries like a little higher charge level than is found in a lot of vintage bikes (Airhead BMWs use 13.8 volts, and come in at fairly high RPMs). I've used the batteries in old bikes that I upgraded the charging system on.
Early Suzukis (70's and early 80's) had a charge rate of 15.5 volts. That is what the factory called for. Never saw another brand of bike that did that. 15.5V is enough to blow up a lithium battery.
I usually go as big as possible when using a lithium, as they lose a lot of punch when it is stupid cold out. Turning the key to the 'Park' position for a minute and lighting up the tail light will put enough draw on the battery to warm it up internally and help the cold weather cranking.
And the usual stuff, upgrade the hight amperage wires. Check all the charging system connections.