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Old 03-21-2011, 09:13 PM   #1
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Location: netherlands
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Default what battery pack do i need

have to batterys in my boat
it's a 2400scr with a 4,3 mercruiser 6-cil vortec
one is a 75 ampere and the bigger one is a 88 ampere
wich one is to fire up the engine

why this question ?
seems like the big battery has the thinnest leads and the smaller battery is connected to the engine


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Old 03-21-2011, 09:42 PM   #2

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I assume both batteries are connected to a battery switch, yes?

The answer is - which ever one will start the engine!

However, both batteries should be connected with the same size wires - unless there is no battery switch. If there is no switch, then I would have to guess that the smaller battery, with the thicker leads, is meant for the engine and the larger battery with the thin leads is for the "house" (navigation and other lights, stereo, GPS, etc) electrics.


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Old 03-22-2011, 01:16 PM   #3

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The starter will draw a huge amount of amps for a very, very short time. Several hundreds. The house will draw very little in amps over a long time. The guage of the cable is sized to accomodate the load. The starting batt. does not need to have a large capacity, but does deliver high amps over that short time. Once the starter starts the engine, the alternator recharges what was depleted.
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