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forester15 asked

SmartShunt new user questions

New 500A SmartShunt installation in an RV with 2 12V batteries connected in parallel. The batteries are from 2015 but still working just fine. Full charge is 12.7-12.8. I have a knife type disconnect to take the batteries completely offline for storage as there are some small draws (parasitic) that circumvent the RV's "on/off" switch. So I turn that off and pull the knife switch which turns off all loads to the battery set. I installed the SmartShunt between the system negative loads and the knife switch attached to one negative terminal. Questions:

1. When I installed the SmartShunt, as soon as I attached the + wire to the battery the shunt went active even before I closed the knife switch. This means the circuit is finding ground somewhere else. There is a whole circuit through the battery isolation monitor (BIM) that reach the chassis (starter) battery to control charging from the generator and also from the chassis alternator. Also there are some 12V items that will run even with the knife switch open, for example the power step and the rear stabilizer jacks. So I assume this is OK that it started up immediately, but wanted to confirm that. (It was not measuring current to/from the battery bank because was not attached to them yet, but it was running with the blue light blinking ready to connect, and it did connect.)

2. For RV storage, I don't want the SmartShunt to stay in standby mode even thought it's a small draw. It is stored outside in deep cold (can be 0 to -20F). Should I disconnect the + line fuse to the shunt? Or just not worry about it at all?

3. For charge level, the manual recommends 13.2 which is my charge float level. But manual also says to set 0.2-0.3 below the float level. If I set it at 13.0, when would the charge level ever be reached since the charger will keep the level at 13.2? I'm inclined to go with 13.2 and ignore the advice to set below the float level??

4. The batteries are unlabeled and unbranded in any way but have a sticker "D27DG-160." The closest I can find anything on is D27DC-160. This shows a reserve capacity of 160 mins. @ 25A which is 66.66 aH. I would have thought the capacity to be higher but does that seem like a good number? If I double that for the two batteries I get 132 but would probably use a lower number given the batteries' age. Thoughts?

5. Every time I connect with the Smart Connect app, the Trends graph starts from scratch. It retains no history, so it's not possible to see "trends." The History tab retains its data but no matter how far I zoom out the graph, it shows only the last few seconds or minutes that the app is connected. As soon as I switch to another app, the history is lost. The manual states in the Trends section, "Providing that the firmware battery monitor is up to date, the battery monitor will store up to 45 days of past data." How can I capture and view the full history?

Thank you!


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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

You definitely need to find the sneak path that's causing the SmartShunt and other devices to be powered when your switch is open. Otherwise, you will be draining your battery. Is there another source of DC power in your RV? Maybe your converter if you are plugged into shore power?

There should be NOTHING on the shunt's battery terminal except the battery bank. Your disconnect switch should be connected to the load side of the shunt, then all loads connected to the opposite side of the disconnect. Even the chassis grounding connection should be made after the disconnect switch.

That puts the shunt power before the disconnect. Victron recommends leaving the shunt powered as it's power consumption is tiny (< 1mA) which is usually less than the self-discharge of your batteries. At that rate, it would take 100,000 hours or 11 YEARS to discharge a 100 AH battery if it started fully charged. Disconnecting the shunt will cause history and the current SOC to be lost. Reconnecting power would either require a full recharge to establish SOC again or if the option is set, SOC would be reset to 100% at power up which would be incorrect.

If you really need to disconnect the shunt, I recommend a separate on/off switch in it's power lead.

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