I gotta friend who wants to hook up a dry cell rechargeable battery to run his computer in his car. (no its not some crappy job, hes pretty much got his whole computer running the accesories in his car) he wants to be able to keep his computer on stand by when he turns off his car without taking too much from his main battery. but the battery he is wanting to use im pretty sure is a dry cell. im not sure what kind though because the website didn't list it http://www.batterymart.com/battery.mv?p=SLA-12V7-F2 hes going to attempt to hook it up with diodes and such so that the computer will be the only thing taking power from his second battery. but charge will flow the other direction to help charge it. but im worried about A) too many amps flowing through to the battery, and B) fast charging a dry cell battery. now im no battery expert but i think hes gonna have a problem. what do some of you people with more experience think?