(ET) New batteries in E20

I procrastinated long enough on this, so I went ahead and purchased a new set of US Batts 2200's for my E20. My tractor is up in the California Foothills in the Gold Country, which has had a ton of rain this year. Rain = Weeds^ big time around here and I needed to be prepared for the season. Pulled the old set out, which I purchased used from golf cart shop 3 years ago, and plopped the bran new puppies in. Batts were charged to 80% from dealer so I plugged in the Landis controlled stock charger and let it charge overnight. Next morning I placed my plow attachment on tractor and moved serveral piles of downed tree limbs over to the burn pile. Plenty of power now with no problems in the 2 hours this took to push piles around. Next I took plow off and attached the front mower deck and started to cut approx 2 acres of foot high growth. Problem started shortly after this which I noticed upon going up inclines on the property. I used to cut in L with no noticeable change in tractor speed going up or down hills. My cruise control went out a few years ago and I have not fixed it yet. This time when I started to go up a hill, the tractor immediately started loosing speed. Power gauge looked normal with no dip that would indicate loss of electrical power. On a couple of small hills I actually had to drop into LL to continue on, this is with the mower still running. I seem to have only 4 speeds forward now which may be indicative of relay problems? Has anyone had a similar thing happen to them after replacing batteries? Could I be in need of a new #4 card?