[larry barello]

@larry barello , you're the resident Renogy expert, can you chime in?

Whaaaat?🤣

Monitors might not consume much, but it isn't zero. Even the BMS consumes some power and are the primary source of the self-discharge in lithium batteries, hence the shelf-mode for those "smart batteries" (power down the BMS)

For our purposes the shunt monitors probably consume negligible power.

For big power users (heaters, fans, refrigerators, inverters) they often have "battery saver" functions and turn off when the terminal voltage is too low. That saved my batteries once, but the ice cream got pretty soft . At least I still had enough power to turn on the lights and fix the problem.

 

[larry barello]

I can confirm the low ma draw of a sleeping promaster. I had my aftermarket radio mis wired and it was drawing something like 700 ma which killed the service battery after a week of dark and stormy PNW weather (no solar trickle charge). After fixing the radio wiring the current draw of the radio was < 1ma and the total on the service battery was in the low single digits.

Now that my van is completed I need to store it for 6 months. What is the easiest method to prep my lithium battery for long term storage?

Charge it and then disconnect the battery. Charging to 40-70% SOC is considered best, but full works for me. I keep my batteries fully charged the last two years and they seem fine. Only lost .3% capacity (indicated) over that time period (200->199.3 AH).

 

[larry barello]

I have ZERO experience with external shunt monitors. I rely upon the internal ones in the Renogy smart batteries. Any statement I make about electronics other than the ones I own are based on my reading of user manuals and general knowledge about electronics and batteries.

That said, I think fully charging the batteries (using your handy-dandy inverter-charger) and setting the monitor to whatever the stated AH rating is would be a good place to start. 100% is meaningless without capacity. How to determine actual capacity - well, I have some ideas, but I don't really know. Amps in do not equal amps out so simple integration doesn't do it. You need to estimate or know the coulometric efficiency of the batteries, etc. A good shunt probably has adjustments for all these factors - or should.

 

[larry barello]

The question is when you first install the monitor. It says to set to 100% 0r zero fullness, regardless of how full the batteries are. That seems odd to me.

Ok, I read the manual. It looks like a good product.

RNG-220819-RBM500（EN） (mybigcommerce.com)

I think one needs to read the manual and understand all the user settings before it will accurately display values. There is no guidance, but the terminal voltages (full and empty) are going to be different for Lithium and various lead acid batteries. Determining full and empty will be essential for the unit to self-calibrate.

 

[larry barello]

I would think 5 Ahrs drain in 21 days on a 95Ahr starter battery should always crank over the engine ,,, no?

Sure, sounds good to me. Under all weather conditions (well, down to 11f) the Pentastar has always started with almost no cranking. I would expect you could start the car with a pretty depleted battery. Still, if storing for 6 months, maybe pull the ground clamp?

Keep in mind that at 10ma draw your 95 AH probably is more like 105-110, maybe more. LA chemistry capacity is pretty dependent upon the load. Also, I am inclined to believe the 3ma value. Dunno how much the B2B adds to the load. Best to measure directly with you multimeter:
Clip to negative post and clamp. Remove clamp, measure draw. (oh, yeah, wait for van to go to sleep first )

 

[larry barello]

The manual is pretty sparse and doesn't really explain much. Probably calling technical support will get you more information - they have always been pretty helpful to me. However, just setting the capacity (like you did to 300AH) and a few charge/discharge cycles and the unit probably self discovers the other parameters. It is weird, though, that the default "full" and "empty" voltages are 0v and invalid, yet it seems to work.

I wonder if setting the V full to 13.5 and V empty to 11.0v would significantly improve the performance of the shunt. Gotta ask Renogy about that.

 

[larry barello]

The readings have appeared accurate since then, based on corresponding voltage readings (which is probably how the monitor displays percentage of charge)

No lithium battery monitor shunt uses voltage to estimate SOC. They integrate current over time (the whole point of the "shunt"). The best you can do with voltage is "empty", "full" and somewhere in between. The following is one of many charts on the web that all have slightly different voltages. For measurement purposes the flat area is truly flat with variations of battery, load and age affecting the actual voltage.

 

[larry barello]

Ok, enough of this guessing: I called Renogy, just now, and talked with technical support on how to set up the 500A shunt monitor. You NEED TO SET VFULL AND VZERO for it to work properly. For Renogy Lithium batteries these are the recommended numbers:

• V Full 14.4v (I would use 14.3v to cover measurement errors since 13.5 and above is generally 100%)
• V zero 10.0v (or 12.0 if you want to be conservative and have ~10% reserve but this will affect the capacity #)
• V off 11.0v (this just turns the monitor off; button press wakes it up)
• Alarm 20Ah (low water mark for the alarm, 20% of capacity is typical)
• Attenuation: 0.000% (For Renogy. For other manufactures, call them and find out)

(IMO Capacity, V full and V zero are the only setting that are required. Alarm, Attenuation and Poff are optional)

With the batteries fully charged and the settings screen set appropriately, then:

• Press Ok
• Press << (to go back to main screen)
• Press ^ (to set 100% although this should be redundant if V-full has been set)

With V full and V zero the percentage value should be reset whenever the battery is fully charged or drained. The manual implies that a full discharge/charge cycle will reset/calibrate the capacity of the pack. The manual also implies that you can manually set 0% and 100% with the v & ^ buttons but is silent on whether it sets V zero and V full at the same time.

I am guessing that setting the capacity (e.g.300AH) and 100% is good enough for a general idea of battery status. Must be since that is what @Lolaeliz and @proeddie did and they seem satisfied with the results.

 

[larry barello]

Yeah, HIGH == full, LOW == empty. I would set both. HIGH = 14.3 and LOW = 10.5. Then set 100% on the main screen ('^' arrow) when the reported voltage is in the 14v range.

 

[larry barello]

Any chance you installed it backwards?

Picture of the installation? The main screen, the programming screens?