question

davymy avatar image
davymy asked

Smart Shunt

Hi Guys can you help me?

I fitted a smart shunt to my system, I am also running x1 Roamer 100Ah lithium battery through a redarc B-B charger. My battery is 100% full, however, for test purposes, I have discharged it down to 89%.

Im not sure if I have a fault somewhere because the battery SOC doesn't seem to charge back to 100% when I crank my camper up to charge from the chassis battery...... any idea anyone what the problem might be?


Many thanks

David M

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battery chargingSOC
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4 Answers
klim8skeptic avatar image
klim8skeptic answered ·

@davymy It seems likely that your SmartShunt is not wired up correctly.

Please check this diagram.

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davymy avatar image davymy commented ·
Hi there .. thank you for the reply.

What I can say in reference to the Redarc wiring diagram, I followed diagram then took advice regarding the wiring of the shunt from my supplier.

I was given instructions to connect the earth/ground lead of the Redarc BB charger to the SYSTEM MINUS of the shunt along with the load negative feed from my fuse box. I have then took a negative supply from the TO BATTERY MINUS to the negative post on my Aux battery which is in turn grounded to the shassis..

I hope this makes sense .. I am a novice and learning as I go guys..


Many thanks



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pwfarnell avatar image pwfarnell davymy commented ·
The problem you have is the battery is connected to the chassis ground and so current flowing through the chassis ground wire bypasses the shunt and is not measured. Take the chassis ground wire off the battery and connect it to the load side of the shunt. The only wire that should be connected to the battery negative post is the shunt, nothing else.
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davymy avatar image
davymy answered ·

@pwfarnell Thank you for your reply.. Just so I get this straight.

Do I reconnect my chassis earth lead from chassis to System Minus my side of my Victron Shunt and then take a connection from the (titled) TO BATTERY MINUS to my AUX battery Neg?

Like I said int previous message I am a complete novice to Auto electrics field. I really appreciate your feed back however I apologies for a basic knowledge.



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pwfarnell avatar image pwfarnell commented ·
Your understanding is correct.
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davymy avatar image davymy pwfarnell commented ·
In effect the connection direct from chassis to the SYSTEM MINUS is acting as the earth/ground for my Aux battery? @pwfarnell
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pwfarnell avatar image pwfarnell davymy commented ·
Yes
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davymy avatar image davymy pwfarnell commented ·

Many thanks @pwfarnell so me correcting my mistake will then allow charge back into the Aux battery from chassis battery.


So again in effect the way I’ve wired up previous as blocked change to to my Aux battery?

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pwfarnell avatar image
pwfarnell answered ·

T he previous way did not block charging, it still charged but it did not pass through the shunt so it was not counted. Electrically, the two methods are the same, the correct way means all current flowing into or out of the battery has to go through the shunt so it is counted.

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davymy avatar image
davymy answered ·

Hi there @pwfarnell thanks for the advice you gave me buddy. I rewired my shunt according to your instructions, I'm now getting an accurate reading from the shunt, however, from the readings on the VICTRON APP It reads that I'm pushing low amps when the engine is running through to my AUX battery, around eight/ten amps at most, whereby the REDARC BB charger as an output of 40amps .....this is taking ages to charge my aux battery say from 80% back to 100%. Do you have any ideas/advice on how I can solve this problem?

Or if anyone else can give me some advice I would be grateful

. PS Im running a 100Mh Roamer lithium battery as my AUX


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pwfarnell avatar image pwfarnell commented ·
I am not familiar with the Redarc B2B charger. I assume that you have it on the correct profile for charging. Other than that generic thoughts are what voltage does it reach at the battery and does it reach what has been set. Have you checked your system for tight connections. Have you seen if there is any voltage drop, i.e. What are the battery voltage and the charger output voltage just in case you have a poor connection. Some B2B chargers reduce the output current if they get too hot, is the charger somewhere that it can get cooling air to it.
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davymy avatar image davymy pwfarnell commented ·

@pwfarnell Yes I've checked connections, and all seem tight. I haven't checked for a voltage drop. This is something I will check tomorrow.

I will check the positive cable from the BB charger that feeds the aux battery. plus I will check the current state of charge of my Aux battery and go from there.

Many Thanks

DM

ps could my alternator cause this problem? reasons for asking, when I crank the engine the alternator sometimes makes a clicking noise before firing up. My chassis battery is healthy and fully charged I've checked it.

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pwfarnell avatar image pwfarnell davymy commented ·
Re your comment about the alternator, does your RV have one of the smart alternators managed by the engine (Euro 5 or 6) because at times these can go into a low voltage float mode to reduce power consumed by the engine and if the alternator has a low voltage I would have assumed that the B2B boosted this, but again I am not familiar with the Redarc.
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