I've been using Yuasa batteries for my last 2 MCs for many years. I had a Yuasa YTX20HL-BS Battery in my 2002 Concours since Sept 2008. I use Yuasa Smart Shot 12V 1.5 Amp Battery Charger for the last 6 + years, and, mine has worked great. I went out 2 weeks ago to take the MC for a ride to work, and I got the bike to turn over twice and then it quit. Nothing, no click, no lights, no dash lights, just completely dead. The following week I had time to check the battery. It was @ 8.3 VDC. I put the battery on the charger, and it took several hr.s to get to full charge (the Yuasa charger shows a green light when fully charged). After I pulled the charger off, I put a voltmeter on the battery, and it showed it was dropping voltage rapidly right off. I did some checking online @ the Yuasa web site, and it says that a fully charged battery should read 12.60-12.80 VDC. (well, that's with sulfate stop...)
Since the old one was dropping off below 12.6 after it reached full charge, I figured after 5 yr.s, 9 months it was time for a new one. I purchased another Yuasa YTX20HL-BS, same as before since it had worked well. I followed the directions to the letter filling the maintenance free battery. Mostly it involves waiting to let it fill, then waiting a full 1 hr to allow the AGM plates to fully saturate. On the battery it says it's a 18.9Ah (20 HR) battery. Reading on top of the battery, it says you could apply a 9 amp charge for 1.5 hr.s. I had a Schumacher 2a/10a/50a automotive charger. Since the Yuasa 1.5 Amp charger would take awhile and the battery said it could take a charge of 9amp @ 1.5 hrs, I used the 10amp for 45 min.s. I came back @ 40 min.s or so and the battery showed on the charger to be at zero amps, fully charged. It wasn't hot, and showed 12.65 VDC across the terminal. I put it in the MC, and put the other Yuasa automatic charger on just to check to see if it showed it was fully charged. I left it on for an hr, and it never showed the green light...
The voltage reads 13.4 or 13.5 just after the charger is pulled off, and then drops 12.65-12.75 VDC but doesn't go any lower. My notes from 2008 showed the last Yuasa YTX20HL-BS topped off @ 13.2 after the charge.
My question is; did something happen to the battery using the 10 amp charge from the Automotive charger that now affects the battery so it wouldn't take a full charge from the Yuasa 1.5 amp charger?
Any opinions, thoughts would be appreciated. I'm figuring as long as the MC battery doesn't fall below 12.6 after it's been sitting, then it should be ok. It's just that I usually go out every week, and put the Yuasa automatic battery charger on it once a week until the charger shows the green light. I've been gone for a week, and I checked the battery once I got home from my trip, and it was 12.7 VDC. I put the Yuasa charger on it, and left for 2 hr.s. I came back and the charger was warm, (not hot) but no green light. I took the charger off, and VDC drained off from around 13.2 or so, to around 12.7 pretty quick, but didn't drop below that. I'm going to leave the charge on all night and see if it ever goes green. I keep thinking I should not have used the 10 amp charge for the 45 min.s, as maybe it was too much.
Any idea, and/or thoughts would be appreciated. Thanks