A month ago I purchased and AGM battery for my Yamaha XS650, a unit which was supposedly shipped fully charged. When it arrived I put a meter across it and got 8.4 volts. I attached a Battery Tender for 24 hours...still 8.4 volts. I found an article in an old version of Hot Rod magazine which had interviewed a technician from an AGM battery manufacturer and his response to charging issues was, if chargers can't detect at least 10.2 volts in a battery they assume that there is no battery and won't cycle on. The tech recommended hooking the battery in parallel with a good battery and attaching the charger to the good battery. I tried it with my 25 year old bulk charger and within 45 minutes was looking a 11.9 volts on the AGM and another hour had it topped off. The technique worked great, probably to the chagrin of those selling those $100 hoochie koochie chargers.
