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post #10 of Old 07-06-2010
Mark F
Join Date: Mar 2006
Location: Felton CA
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I have two separate banks (sets) of batteries. One is made up of four 12 volt group 27 AGM batteries connected in series. Each battery is rated at something like 90 amp hrs, by connecting them in series you get 48 volts and the amp hrs stay the same - 90 ah. The other bank is four group 31's rated at 110 ah, so 48 volts and 110 ah. Your 130 ah Trojan's are a real good start and should do fine for local stuff. I like having the redundancy of a second bank even if I rarely need to dip into the second bank. You should find out what the amp draw is for 3, 4 & 5 knots of motoring boat speed. Also the proper prop is important to performance. I started with a fixed two blade 11x8and got 3 knots at a 20 amp draw. Now with a fixed three blade 12x10 I get 4knots at 20 amps. Does the Bristol have a way to monitor the batteries?
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