2oldeshoes

Hello There, Can any one help me, my 650 US custom has lost it's charging, so far through listening to others i have spent over £700 trying to fix it, i have replacd the brains/black box, carb diphrams, changed it to points, all because of it miss fireing, when the charge in the battery got low, i can do about 20 miles then the battery that is fully charged runs down, so it has to be the chargeing system, any ideas on what to look for next, would be welcome, thank you. Fred.