How do you lithium users monitor state of charge?

[BAD ORCA]

Im just starting to educate myself on lithium systems and have become aware that lithium does not drop in voltage like lead acid does as its depth of discharge decreases. Since lithium holds a high voltage throughout most of its discharge cycle, how do you guys monitor the lithium banks current state of charge? i use an SG-200 on my lead acid bank but i dont see any similar monitors for lithium. Is monitoring state of charge incorporated into the displays on products like the Victron inverter/chargers or is it done another way?

[ThereAndBack]

Victron BMV 712. It counts amps in and out.

[hjohnson]

I'm building a DIY lithium battery for my Ericson 27. In our case, the state of charge will be measured by the BMS itself. We're building a fully integrated system, using a REC Active BMS. One of the things it does is play with our Victron Gear, and tell us what the SOC is.

[BAD ORCA]

Originally Posted by hjohnson

I'm building a DIY lithium battery for my Ericson 27. In our case, the state of charge will be measured by the BMS itself. We're building a fully integrated system, using a REC Active BMS. One of the things it does is play with our Victron Gear, and tell us what the SOC is.

Oh interesting. I was wondering about that. Havnt learned the ins and outs of the BMS's yet. Im assuming the Lithionics batteries that have internal and external BMS will do the same.

[Pete7]

We monitor the BMS via the app to see what the percentage of charge is, but accept this isn't very accurate, probably voltage based. Equally we have a printed table and check the battery voltage occasionally, again not very accurate, but actually it doesn't matter.

Whilst its important to watch lead acid is fully charged, we don't worry about the LFP if its at 60% or 90%. We sometimes boil the kettle if its getting close to the knee (greater than say 95%) and have used the engine to add charge if bad weather is coming in, rest of the time solar just does the charging nicely.

It does take a change in mind set which can be quite hard to do if you are used to baby sitting lead acid.

[bergius]

We use a Victron SmartShunt. No display, but easily viewable via a smartphone.

We also have a Cerbo GX so we get a very nice overview of the state of the boat

[BAD ORCA]

Originally Posted by Pete7

It does take a change in mind set which can be quite hard to do if you are used to baby sitting lead acid.

That wont be hard. Im so fed up/disgusted with lead acid.