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Old 14-03-2018, 12:32   #1
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Basic question.....

Small diesel (Beta 25) auxiliary.

Rolling amps for the starter is 100 amps...

Micro second initial spike to roughly 300 amps...

Plan is carry this load to a common bus rated at 250 amps continuous.

Is this OK??

Or should I over size this bus to accommodate the spike?

Tx.
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Old 14-03-2018, 12:36   #2
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Re: Basic question.....

Iíve got our engine (same block as a beta 28) attached to a slow blow 250 amp fuse on the start battery and havenít had a problem yet. The spike is of such short duration that it develops unmeasurable heat.
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Old 14-03-2018, 12:51   #3
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Re: Basic question.....

Quote:
Originally Posted by Sailmonkey View Post
Iíve got our engine (same block as a beta 28) attached to a slow blow 250 amp fuse on the start battery and havenít had a problem yet. The spike is of such short duration that it develops unmeasurable heat.
Great ........thanks.

Plan is to fuse at the battery with a 300 amp fuse. Was curious about the bus. And if you have fused with 250 amp and it has not blown .........should be no problem.

That is my gut feeling......but wanted to toss it out to the forum.

Cheers.
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Old 14-03-2018, 23:09   #4
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Re: Basic question.....

if you put the 2 wires on the same post, then it doesn't even mater what the buss rating is.

gernally things are rated with a continuous rating and a cranking rating (which is much higher)
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Old 15-03-2018, 02:07   #5
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Re: Basic question.....

I've used 250A fuses on my house banks which also connect to the starter of a 33hp motor for some time and never had one blow. Fuses tend to be more tolerant of regular but brief overloading then breakers.
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Old 15-03-2018, 07:16   #6
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Re: Basic question.....

Quote:
Originally Posted by smac999 View Post
if you put the 2 wires on the same post, then it doesn't even mater what the buss rating is.

gernally things are rated with a continuous rating and a cranking rating (which is much higher)
Thanks Smacc,

That was my plan. 1/0 cable from the main batt switch to a 250amp common bus. 1/0 cable from the bus to the starter shares the same post as the switch.

Thanks for the confirmation.

S
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