The Dcell size you are thinking of are lithium ion. I wanted to do that but by the time you figured the cost for all the parts, a new one from Ballistic was about $30-50 more. The other part that dissuaded me was the fact that many of the available batteries were from China and were purportedly fake. My first one blew up in about four miles because I had knocked the sense wire off the regulator. That one I ripped apart and only one cell was wrecked. It had seven still at 3.0-3.3v each. I've had the other one for two seasons. It spins it over great. I originally set it up with a relay to get actual battery reading for the regulator, but the regulator is setup for a battery to get in the 13's for voltage. Lead acid are 6cells do 2.1 v each or 12.6v. LiPO4 batteries are 4 cells of 3.3 or 14.2v. They come in groups of 4, 8, 12, or 16 cells. Mine is eight cell. Mine would slowly drain the battery when I had it wired through the relay. I was really disappointed and ready to change out my reg/rec. but I got rid of the relay and ran it up through the start switch as normal and it has been fine ever since. They need over 14.2 to charge up. The guys who run them on sport bikes usually have a port on them to trickle charge them at home.
If you go the LiPO4 route, they want Goldwings to have a 16 cell battery, about$300+. An 8 cell seems fine for mine, the hybridized 1200,000. Another weird thing about these. If you turn them on a few seconds, then wait a few minutes, their voltage goes up. Mine sat for two months last winter, and when I checked it, it had 13.8 volts. Twenty minutes later, it had 14v, just using the multimeter "woke it up." They say in cold temps to turn the key on for a few seconds and wait a few minutes before starting it.
I bought an agm from China for my stock 77. One season, so far so good.
