Herk...you're right! I totally forgot about how the amp ratings don't change when connecting in series to make the 12 volts. Thank you for correcting that, he'll have to run 2 sets of 2, meaning 2 6 volt in series and then two pairs in parralel to make the 400 aH's he's looking for.
Also, I think you meant 240aH at 20 amps...not hours. One thing I noticed about battery ratings is that not all companies rate at 20 amp draw. You'll see either 25 amps or at 100 amp draws, which makes it difficult to compare side by side without recalculating their ratings. Anyway, thanks again for keeping me honest on my reply
Where we've been:
2000 Rockwood Roo M-18 Hybrid
2006 Dodge Ram 2500 Auto 5.9 Diesel
Gone but not forgotten -1986 Rockwood 1003 PUP