My alternator had failed a second time, so Rob and I were going to fly from Middletown to Dayton General to have it replaced. We took off from Middletown with a dead battery. When the airplane had enough speed and a positive rate of climb, I brought the gear up as usual. Unfortunately the gear is brought up by an electro-hydraulic motor, and I had no battery power. The gear came half-way up and stopped. Luckily Rob was there to hand-pump the gear back down.