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Hey Folks. I am looking for details on sizing a smartshunt. For example, for the 1000A model, can it handle higher inrush from cranking or is 1000As the the absolute limit? What happens when current rating is exceeded?
I have Detroit 6-71s and i read that they typically have a 10HP starter, which i think works out roughly to ~700As @ 12VDC (??).
Not answering your question but why would you put the starter through the shunt? Normally the starter motor would bypass everything else and be directly connected to be batteries via only the starter solenoid. This leaves your shunt to be sized by just your normal loads.
You may have a specific reason for doing this but if not, might be worth reconsidering your wiring.
To be honest i am asking myself the same question :-). My original intention was to monitor a house bank (Vs. cranking bank), and then realized that i would be missing alternator current going into the house bank as my grounds for each bank and engines are all tied together at the batteries (between house bank Neg to Cranking bank neg, 2xEng grounds to cranking bank Neg). I think i need to move the grounding connection which connects the two banks together to go from cranking battery to bus bar on the "other side" / upstream of the shunt. This way current from house-alternator flows to House batteries, shunt, cranking bank / eng Neg, but cranking current flows cranking battery, starter, back to cranking bank without going through shunt(?). Makes sense?
Yes, makes sense. You could end up having to have a new earth cable direct from starter to battery to bypass the shunt rather than the starter connecting to an earth point.
I have a 400A rated shunt connected to our 300Ah 4 cell LiFePO4 battery. It is the only battery in our motorhome and powers both the truck and the RV. It has happily carried the many hundreds (thousands) of 3.9l turbo diesel truck startup currents over the last 6 years of full-time travel. Highest ever peak current observed was 742A but only for a fraction of a second. The shunt still looks pristine.
