“User” controller settings for lithium battery using Rich solar 40amp

[Gumby]

The issue is that Rich Solar 40amp controller is showing 0.40-0.44 amps always going into the battery. I’m using the “user” settings, I have a lithium battery with BMS, 12.8v 300ah.
I’ve changed settings several times trying to get zero amps going into the battery...I can’t seem to find the correct setup for this controller. I’m looking for charging of the battery to be 80%/20%....I’d like charging to start when the battery hits 20% discharge and charge till it reaches 80% of full charge.

 

[snoobler]

Welcome to the forum.

You are on a snipe hunt.

The ONLY way to establish SoC is with a quality battery monitor. The % reading on your controller is beyond meaningless as it's purely voltage based and in no way represents anything remotely close to an actual % state of charge.

If your goal is to maximize cycle life, set bulk/boost/absorption to 13.8V and float to 13.6V.

Stop discharging at 12V.

 

[Gumby]

Welcome to the forum.

You are on a snipe hunt.

The ONLY way to establish SoC is with a quality battery monitor. The % reading on your controller is beyond meaningless as it's purely voltage based and in no way represents anything remotely close to an actual % state of charge.

If your goal is to maximize cycle life, set bulk/boost/absorption to 13.8V and float to 13.6V.

Stop discharging at 12V.

Hi! Thanks for the reply. Yup...I got all that going on. Controller always shows that half amp going into the battery. Now I don’t see that half amp charging because I believe it’s not enough to start the “charging” process in the battery. What ever the details are of that, I don’t know exactly, but I know enough to be dangerous ? I have limited knowledge of solar.

 

[Substrate]

In the user settings, for LFP don't forget to disable temperature-compensation.

If the bank is fully charged, and you are seeing constant current flowing, like 0.44a, is it possible that the internal bms balancers are pulling that current?

Note too that striving for zero-amps tail-current on a full time basis is somewhat unnecessary and unhealthy in the long term.

I may be wrong, but perhaps the current you are seeing are the balancers doing their thing on a capacity that large.

 

[snoobler]

Hi! Thanks for the reply. Yup...I got all that going on. Controller always shows that half amp going into the battery.

did you confirm this with a clamp ammeter or some other device that measures current? It could just be a calibration issue where the SCC is in error.

Now I don’t see that half amp charging because I believe it’s not enough to start the “charging” process in the battery.

I really don't know what you might be talking about here. ANY current is enough to start the "charging" process in a battery unless something is wrong with the battery.

 

[Gumby]

did you confirm this with a clamp ammeter or some other device that measures current? It could just be a calibration issue where the SCC is in error.



I really don't know what you might be talking about here. ANY current is enough to start the "charging" process in a battery unless something is wrong with the battery.

I thought lithium batteries don’t start to charge till past 13.2 volts(?)....something about it not stimulating the cells. And that would be why float levels are lower then lead acid, because lithium needs no float.[?]. EDIT....I do have a trouble ticket in with Rich Solar.

 

[Gumby]

In the user settings, for LFP don't forget to disable temperature-compensation.

If the bank is fully charged, and you are seeing constant current flowing, like 0.44a, is it possible that the internal bms balancers are pulling that current?

Note too that striving for zero-amps tail-current on a full time basis is somewhat unnecessary and unhealthy in the long term.

I may be wrong, but perhaps the current you are seeing are the balancers doing their thing on a capacity that large.

Yes...the BMS. I thought about that too. It’s a brand new system & battery. I don’t think I’m hurting the battery and that’s my main concern.

 

[snoobler]

I thought lithium batteries don’t start to charge till past 13.2 volts(?)....something about it not stimulating the cells. And that would be why float levels are lower then lead acid, because lithium needs no float.[?]. EDIT....I do have a trouble ticket in with Rich Solar.

Any battery will charge when a source is attached with a voltage that is higher than the battery.

LFP float levels are actually about the same as lead-acid and in some cases, higher than many. Lithium doesn't NEED float, but a solar power system NEEDS a float voltage or the panels will just sit there doing nothing letting the battery discharge until a re-bulk is triggered. This can result in multiple small cycles per day and completely unnecessary absorption charges. Better to just hold the batteries at 95% and let the panels power the loads for as long as you have solar.