At 11:29 PM 10/17/00 -0400, you wrote: >Ken Adrian asked: >1) If I have two batteries with 800 cranking amps each when I hook them >together will I have 1600 cranking amps? >2) What is the difference between amps and cranking amps? >3) How many cranking amps do I need? The boat came with two D8s for >starting batteries and an S/P switch (all three are on the way to the bone >yard.) >Thanks >[edited] >============================================================= >Captain Al Pilvinis responds: >No you will have half or 800, but 800 at 24 volts is equal to 1600 at 12 >volts. >============================================================= > >I find this confusing. If you place two 800 cranking amp 12V batteries in >parallel (plus post to plus post and negative to negative) - you get 1600 >cranking amps at 12V. If you place them in series (plus to minus and minus >to plus) you get 800 amps at 24V. Using a very large capacity battery >switch will serve to parallel these batteries for starting purposes. Al then >states "By the way Cold cranking amps are about twice as much as Marine >cranking amps. Thats why I use automotive Die Hards, a 550 cold cranking amp >battery is equivalent to a thousand amp marine cranking battery." I'm sure >that is true, but it does not alter the computation. It does, however, alter >the power available (amps) to start the engine(s). =============================================================== Ken-------Ron is going into over kill. what HP engines do you have. I know a single Automotive Die Hard will crank a 300 HP diesel for quite a long period of time. We did a test by shutting off the fuel and tried cranking the engine intermittently and gave up thinking we might burn out the starter motor. On my own boat 220 HP I have 3 Diehards in parallel which gives me about 1800 cold cranking amps, about the same as 4000 marine cranking amps. My house bank is also automotive Die Hards 7 year warranty and 2 year free replacement. You can replace your batteries every 2 years, they have a very liberal retun policy. I keep fresh batteries on board all the time. And check the price especially on sale. Just make sure you tell Sears they are for a car othewise the warranty is cut in half. I can see no good reason to have marine or deep cycle batteries on board. . Captain Al Pilvinis "M/V Driftwood"--Prairie 47 2630 N.E. 41st Street Lighthouse Point, Fl 33064-8064 Voice 954-941-2556 Fax 954 788-2666 Email yourcaptain@earthlink.net Website http://home.earthlink.net/~yourcaptain