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Xantrex current monitoring and Blue Sea ACR bypassing the current coil


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2004 original Xantrex inverter/charger. I know there are better ways of monitoring the battery state of charge but this is kind of working. I have replaced the house to chassis relay with a Blue Sea ACR. It works great.  there is a current coil around the house big battery cable with monitoring by the Xantrex that determines current going in and out of the house battery. When on the road, the engine alternator is charging house battery thru the ACR and a short cable and this cable nor the current goes thru the coil. After many hours on the road, both batteries are at 13.8 volts and I would assume pretty fully charged. I fired up the generator the other evening and the Xantrex showed the batteries at maybe 90% but only charging at a few amps. I was originally thinking about buying a longer battery cable to go from the ACR thru the coil and then to the battery. Just walked out to make sure the coil was where I thought it was. Coil is probably too small to get two cables thru. would have to run another foot or so to get to the house battery switch and then all current would go to the battery thru one cable.  My sailboat had a shunt that the inverter monitored and all current going into the battery was accounted for. Looking for what others are doing.

Thanks for the input,

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Posted (edited)

I have an older than yours Xantrex 3012 and the SOC reading (and time to charge etc.) was never making sense or looked correct to me. I assumed the sensing part was internal to the unit so I never considered looking for it or spending time to make it work better. I installed a cheap shunt in the battery ground cable instead and that is working fine for me. The display fits where my original tank level gauge, which is replaced by SeeLevel, used to be. The ground cable is common to all my charging/discharging currents for the house and I learnt to trust it, it now makes sense.

20220603_095732.jpg

Edited by Ivan K
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I am using Victron’s Smartshunt. No display-all the info comes to my smartphone. It has a short range about 5 feet - probably because the Smartshunt is inside an all metal battery box. 
 

I also have used Victron’s BMV-712.  Both worked great. I did have to run the cable into my rig - the Bluetooth range was much better - probably because the transmitter is in the display and the display was in the living space. I found I never looked at the display and always just looked at my phone, so I replaced it and gave it to my dad for his 5th wheel. 
 

Both are great products and once dialed in give great results. My favorite feature is a “Time Remaining” calculation that shows (at the current use rate -over the last three minutes) how long the batteries will last until they reach the set discharge floor (my lithium’s set at 20%- lead acid’s 50%).  When boondocking I often check this as I am headed to bed - just to make sure there is plenty of power until morning (and we haven’t left something on).
 

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I'm not sure you have a problem.  You don't state what Thule or batteries you have but based on you are charging going down the road, you likely don't have LiFePO4 (Lithium) house batteries.  If this is the case, you might only draw a few Amps while in Float (typically between 85-90% charge up to 100%  That is by design so as to not overheat the batteries at the engine of the charge cycle.  That is also why I recommend not continuing to run the generator after the charger switches to Float unless you absolutely require a full charge.  That last 15% can take hill to 6 - 8 hours depending on number & type of batteries.  That little bit extra is usually not worth the fuel cost. 

It is interesting that the coil you mention appears to be in the positive battery cable.  This is known to be problematic when most than one charging shots for the battery exists, and is why the sensor is typically in the negative battery lead (Between the battery negative terminal and chassis ground.  This will "capture" all the current going into & out of the battery. 

Nothing above is meant to negate the inherent inaccuracies in many inverter states of charge indicators & shunts and dedicated instruments like the Victron series will be more accurate. 

  -Rick N 

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I appreciate the input on having the shunt on the ground. I will give that a try in a couple of days.

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On 6/2/2022 at 9:24 PM, ok-rver said:

2004 original Xantrex inverter/charger. ... there is a current coil around the house big battery cable with monitoring by the Xantrex that determines current going in and out of the house battery.

What kind of xantrex inverter do you have? Are you certain that coil on your pos cable is connected to the xantrex? Seems strange that they'd use an inductive loop where everybody else in the industry uses a shunt.

Maybe it's something different from the way my 2003 was originally set up: trace/xantrex rv2012(?) with RC7 panel. It didn't have a current loop connected to it. It measured current with an internal shunt in the negative cable inside the inverter.

Cheers,

Walter

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I have determined that the coil is part of the Aladdin system. The Xantrex has an internal shunt. working thru what is connected to the green post and to the battery negative.

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  • 3 months later...

I want to thank all for their input. As I stated b4, the coil is part of my Aladdin system. Finally got around to wiring my Blue Sea ACR dash switch and then today I swapped the coil from my positive (battery to the house switch) lead to the negative from battery to the ground point on the frame. Previously, current coming from the alternator to the ACR to the house battery was not being monitored. With the coil on the negative lead, no shore power, the engine running, inverter on and microwave heating water, the drain was 110 amps isolated house to chassis and 20 amps combined house to chassis. The alternator was making up 90 amps going to the positive lead and only pulling 20 out of the house battery, if I read all of this correct. While this may not "fix" the inverter battery state of charge, It does get the Aladdin to be giving me more accurate info.

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