Shunt vs Lithium w/BMS & Bluetooth

[Dr. Ohat]

Hi All,

Was planning on adding a shunt as I transition to lithium. Met with Lion Enerty at Hershey RV show and heard they are coming out with bluetooth in their BMS.

Question - if I can get accurate SOC directly from each battery via bluetooth, are there other benefits to having a shunt?

Thanks,
Greg

[JoeHTP]

Consider where you are to place them, some of the batteries with shunts are not water resistant so should not be in an external battery box.

[richard5933]

If you have a Victron system with a touch screen, having the shunt means that the information will be displayed on the screen. Infinitely easier than having to do it on an app.

Even without the touch screen, I find being able to have both of us see the data on the smaller monitor instantly quite convenient. I'm the only one who will use an app to monitor something like this, so if I expect my other half to ever help keep an eye on things it better be right out there in the open. Besides that, there are times I don't feel like carrying the phone around or even going to find it, so glancing at the monitor is always an option.

Aside from all that, there are other things you can do with the Victron shunt, such as use it to open/close remote relays and activate other devices depending on various set points. Not sure if the BMS on the batteries can do that.

[Lucky Skunk]

We chose to not have the additional monitor inside and to exclusively use the app. I regret the decision!

[uncle_bob]

Hi

The charge data that comes from a BMS is a bit suspect. Even the data from a proper shunt has it's limits. The better result will come from the external shunt.

Bob

[Jcondon]

I have been using the Renogy Smart Lithiums with a wired battery monitor that just plugs in. I also have the app on my phone with the Bluetooth info from the Solar and DC 2 DC chargers. It gives you all of the info you would ever need without a shunt. And it is all plug and play. Very simple to use. And that is good.

[Jcondon]

Originally Posted by uncle_bob

Hi

The charge data that comes from a BMS is a bit suspect. Even the data from a proper shunt has it's limits. The better result will come from the external shunt.

Bob

The Smart BMS is way more accurate than a Smart shunt especially if your Peukert Exponent is off a bit. Calculating the SOC has way more possible errors than reading the SOC from the BMS.

[Jcondon]

Originally Posted by Dr. Ohat

Hi All,

Was planning on adding a shunt as I transition to lithium. Met with Lion Enerty at Hershey RV show and heard they are coming out with bluetooth in their BMS.

Question - if I can get accurate SOC directly from each battery via bluetooth, are there other benefits to having a shunt?

Thanks,
Greg

No. The future is the Smart BMS. Here is the Victron Smart Shunt manual. Just realize you will not have to do any of this! https://www.victronenergy.com/upload...rtShunt-en.pdf

[uncle_bob]

Originally Posted by Jcondon

The Smart BMS is way more accurate than a Smart shunt especially if your Peukert Exponent is off a bit. Calculating the SOC has way more possible errors than reading the SOC from the BMS.

Hi

You are putting a lot of trust in folks who have come up with defective BMS implementations time after time after time ......

There are ton of threads on how to set things up correctly. The shunts work well. The BMS internals are very much an unknown.

Bob

[JohnTF]

1st iff the word shunt is a vari simple component that is in series with the negative side of a battery = the only function it to allow a sensor tap --- the end .
A BMS has this component on a circuit board with many other components .
If you get enough info [ that you want ] then your good .
If you want more info , data tracking , physical display - then you could add a BlueTooth display that mounts to where you need it .
This is a shunt Google search says a little over $22 for 50 amps .
Depending on your abilities , you use the BT in the BMS , add a shunt [ rated for max current of system ] and any kind of metering - to me a meter that records input & output of system .

Buying from a single brand allows extreme lack of knowledge & ability , but at typically very high prices .
I prefer to know enough to reduce costs & repair when issues come up .

All above is just a matter of choice

[Dr. Ohat]

Thanks all for the various perspectives. I guess I can try the BMS w/BT and see how it works and always add the shunt later. My first priority is getting the additional power from the Li batteries.

Thx,
Greg

[jimdelane]

The external monitors such as the Victron 712 or SmartShunt provide better data. It seems that as good of an idea as the internal monitors are - they are not all that reliable.