2009 Vintage battery replacement

[j.r.r.]

Today morning I noticed the OptiMate 4 battery tender connected to my Cal-Vin showing red light which indicates that battery doesn't accept any charge. The bike still has original battery so I think it is time to get a new one. Just to make sure I connected another battery tender (OptiMate 5 used on my second bike) to see if some miracle will take place. Unfortunately, the result is not very promising, after 7 hours the battery tender still shows yellow light which indicates 'SAVE (DEFULFATE) - low battery voltage'. I like to get new battery and not sure if I have to buy the OEM one or there are better options. What about lithium batteries, they are lighter but really worth extra cash?
1. Antigravity 12V 16-cell Lithium Motorsports (http://www.guzzitech.com/store/product/antigravity-battery-bs16/)
2. Lightweight Lithium Battery BikeMaster DLFP20CH-BS (https://goo.gl/LXXs1r)
I don't mind spending extra money assuming I will gain extra reliability, better performance.
Thank you for all comments and suggestions.

[Ncdan]

Jr, I have an 07 calvin and I think they are the same bike for the most part. I would suggest you get the best and highest capacity battery you can get because the charging system on our bikes sux. Therefore you need all the stored power possible.

[guzzisteve]

I would get rid of EVAP can and put in a full size EV batt in it. I use this---

http://www.sunxtender.com/solarbattery.php?id=1

They last around 14yrs cost around $100

[ramarren]

My V7III Racer had, four months old, started to discharge overnight for no reason. When I checked the charging system after recharging it yet again, I got some very 'out there' readings, a sure sign that either the battery, the charging system, or both were toast. Wielding Occam's Razor, I decided to change the battery first.

I replaced the defective battery with an AntiGravity BS-12 from GuzziTech.com. MUCH much better cranking, a re-check of the charging system shows it is right on the money, and the bike idles and runs much better. I suspect that the OEM battery was simply dying from day one and throwing the regulator into fits trying to keep it charged, throwing the overall system voltage up and down in the process and making the idle go wonky, etc.

(The dealer is warrantying the OEM battery and giving me a store credit. They've been great.)

[j.r.r.]

Thank you all for advice. Last night I ordered new lithium battery https://gpbikes.com/antigravity-yt12bs-16-cell-480ca-lithium-battery.html and new battery tender https://gpbikes.com/optimate-5-amp-lithium-battery-charger.html. I will hold with installation till riding season, another couple months. But... looks like I jump the gun because when I went to garage today morning battery tenders on both bikes shows two green lights which means 'all good'