Any MPPT charge controllers charge lithium's by capacity?

Hello: I have an EPever Tracer MPPT solar charge controller in my travel trailer. I have set the lithium parameters according to the setup booklet, however the major charging only takes place when batteries are under load. As soon as the load is removed, the charging drops off. This is even as the battery capacity diminishes.



Example: 400 amp hours of battery, 100% capacity, 14 volts, no load, no charging.

400 amp hours of battery, 100% capacity, 13+- volts, 20 amp load, 20 amps charging.

400 amp hours of battery, 60% capacity, 14 volts, no load, trickle charging. (takes many hours or even days to bring back to 100% capacity.)



My tracer seems to only apply charging compensation under load, not capacity.

Any parameter tweek ideas to bulk charge for capacity?



Thank You for any assistance.

Alpen54 said:

have set the lithium parameters according to the setup booklet

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The values you have used would be useful to the discussion.

How are you determining capacity? The values given by Epever will not be correct.
The problems you are encountering are similar to others using the Epever charger, this may be resolved by adjusting charge perameters.
Other users have no issues .

More details of your setup would be useful, model of charger, make and capacity of battery, system voltage, solar array power and configuration, load, system diagram.

Alpen54 said:

400 amp hours of battery, 60% capacity, 14 volts, no load, trickle charging. (

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If the battery voltage is 14.0 volts with a zero or very small current under charge conditions, then its possible the battery is almost fully charged and In protection mode.
If, under these conditions, the charger is disconnected and a small load, 1 or 2 amps is applied, what is the battery voltage ?

Alpen54 said:

My tracer seems to only apply charging compensation under load, not capacity.

Any parameter tweek ideas to bulk charge for capacity?

Click to expand...

The parameters to set are - Throw away the useless time wasting Epever and get yourself a Victron SCC.

Maybe I am putting too much trust in the monitors, but here is what I put together.

4 100 watt panels (can’t remember the manufacturer, but definitely not cheap)
4 100 ah lithium batteries in parallel (Will opened them up on YouTube to find made by chins).
Epever tracer mppt 40a with MT50 monitor/parameter setting
Renogy battery monitor with all loads connected directly to 500 amp shunt at the battery bank,
3000 watt pure sign wave inverter (that was inexpensive, put performs perfectly)

Settings:
Charging:
Charge limit 14.6v
Over voltage disconnect 15v
Over voltage reconnect 14.2v
Equalizer charge 14v
Float 13.8v
Boost 13.8v
Boost reconnect 13.2v

Discharging:
Low voltage disconnect 10.8v
Low voltage reconnect 12.4v
Under voltage warning 11.6v
Under voltage reconnect 12v
Discharge limit 10.4v
Over discharge disconnect 10.4v
Over discharge reconnect 11.6v

Equalize duration 120 min
Boost interval none


So, a scenario is starting with 100% charge and approx. 14 volts, no load, no charging. (makes sense)
Turn on the A/C, run for a while, batteries at 90% charge, 13.8 volts, 108 amp load, charging as much as the panels provide at the time, up to 28 amps. (also makes sense).
Turn off the A/C, batteries at 90% charge, back to approx. 14 volts, charging drops off to minimal. I sort of understand the MPPT will charge by drop in voltage, not state of charge (capacity), but lithium’s voltage don’t seem to drop much except under load. It takes many hours to bring the charge back to 100% under this setup.

Alpen54 said:

:
Charging:
Charge limit 14.6v
Over voltage disconnect 15v
Over voltage reconnect 14.2v
Equalizer charge 14v
Float 13.8v
Boost 13.8v
Boost reconnect 13.2v

Discharging:
Low voltage disconnect 10.8v
Low voltage reconnect 12.4v
Under voltage warning 11.6v
Under voltage reconnect 12v
Discharge limit 10.4v
Over discharge disconnect 10.4v
Over discharge reconnect 11.6v

Equalize duration 120 min
Boost interval none

Click to expand...

These settings are not quite correct.
The most important is 'boost' voltage, normally termed absorbtion voltage. This is the 'target voltage' the charger aims for. Once it reaches this value, it should hold this voltage constant for the 'boost duration'. (absorbtion period)
Typical values recomended by battery manufactures are absorbtion volts 14.2 to 14.4, absorbtion duration 60 minutes.
Float voltage, set to 13.5 volts.
Equilisation is not needed for lithium, occurs every 28 days, set volts same as boost volts and duration to 10 minutes.

Almost of all the other settings relate to the load output control .

The SOC reading on the Epever is not accurate, ignore completly.
It's not clear how you are measuring voltage, its possible any reading on the Epever is in error.

Under charge the battery voltage will be the same as boost volts if the battery is in a high state of charge
With the battery under no charge or load, the voltage 'full' will be 13.4 volts or higher.
If the 'full' battery is loaded ( not under charge) the voltage will fall to around 12.8 to 13.2 depending on load.

Expect a rested battery, no load or charge, to have this relationship between voltage and SOC,

Many 'give up' with Epever controllers and move to the Victron Smart units.
One item that will give a accurate SOC is a battery monitor, the 'gold standard' is the Victron Smart Shunt'
.

Even with trying all different sorts of settings, some Epevers sometimes don't respond to loads.

Here's where I documented my ones behaviour from this post and on in this thread...


That's why I say you could end up wasting a lot of time on the Epevers and not solve the issue and end up getting a Victron SCC anyhow then wish you did it sooner.

Battery is not at 14.0 volts if down 10%. Can't get there from here. Have you verified voltage with a separate voltmeter previously tested on something else?