question

dermot-dublin avatar image
dermot-dublin asked

Starter battery wiring to smart shunt

Hi all I hhave installed a smart shunt in my van- all working fine.

However I now would like to activate the starter battery monitor wire.

My house or auxiliary battery and system is not grounded to the chassis of my van.

If I connect the red supplied wire to my starter battery how do I give it a negative connection to complete the circuit?

SmartShunt
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6 Answers
grayjp5 avatar image
grayjp5 answered ·

I suppose you'd have to connect your buss bar to the chassis to make it work, or run a negative with the positive to your starter battery. You're running the wire anyhow.

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grayjp5 avatar image
grayjp5 answered ·
The shunt should be grounded if installed correctly.?
2 comments
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grayjp5 avatar image grayjp5 commented ·

Re:

1654120189046.png

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1654120189046.png (17.5 KiB)
grayjp5 avatar image grayjp5 grayjp5 commented ·
The only information you'll get from your starter battery (as wired) will be voltage.
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grayjp5 avatar image
grayjp5 answered ·

I guess I should've posted my comments in the answer section..

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Sarah avatar image
Sarah answered ·

The shunt relies on a common ground between the house and starter battery to measure the starter battery voltage. This is common in most van/boat installs. An alternative is to use a smart battery sense for the starter battery.

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kevgermany avatar image kevgermany ♦♦ commented ·

@Dermot Dublin

To add to Sarah's answer. Connect the load side of the shunt to a good chassis ground.

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roscoe avatar image
roscoe answered ·

I have a question re this topic, new to this forum and not sure if this is the correct place to ask…. But the topic is very similar so here goes….

I’m connecting a smart shunt to my aux battery, just wondering if I can connect the positive side to a positive feed (6 awg wire) which comes direct from aux positive battery terminal to a dc-dc charger located in rear of my truck above house battery …?

This would save me running the wire all the way thru the cabin of vehicle. Negative goes to a common ground in rear as stated by you…

Would the fact that the positive is also connected to dc-dc charged affect the accuracy of smart shunt voltage display?

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pwfarnell avatar image
pwfarnell answered ·

Yes you could do this but when the battery to battery charger is charging the measured voltage will be lower than the actual starter battery voltage. How much the error will be can not be determined from your information. Use a voltage drop calculation (there are many on line ones) to estimate this. Only you will know if this is important or not to you.

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