Which Charging Profile for Lithium? (Samlex EVO-1212)

[Sabre602]

OK, I've got my two 12 volt, 280 Ah batteries built, each using a 120 amp Xiaoxiang BMS (JBD branded RadioB Tech). They'll be wired in parallel on my boat, supplying and charged by a Samlex EVO-1212 inverter/charger. (We will also charge from a Kisae DMT 1250 Abso DC-DC charger from the alternator with built-in MPPT solar controller from future panels that will be installed later). I plan to use 10% to 90% SOC as our useful range in order to promote pack longevity.

The Samlex has a rich variety of programmable options, and I have the remote panel that gives access to this. With much help from you all, I have set my initial voltages for inverter function, but now I'm looking at programming the charging profiles to use when we're at the dock, tied to shore power. During trips we'll want to put the batteries at a high state of charge when we occasionally stop overnight at a marina for shore power. When at our home dock, we can set the voltages to keep the batteries happy at a middling state of charge...50% or so. An SD card will allow us to quickly swap programs for these two different purposes.

OK, I've set the battery type to lithium, and now have several choices for charging profiles. They are as follows:

3 Stage Type 1
Bulk Stage at constant current until desired voltage is reached, then
Absorption Stage at constant voltage for a programmable length of time, then
Float Stage at constant voltage. Reset to Bulk Stage after 10 days in Float or with voltage drop to programmable parameter.

3 Stage Type 2
Bulk Stage at constant current until desired voltage is reached, then
Absorption Stage at constant voltage until current drops to specified amperage, then
Float Stage at constant voltage. Reset to Bulk Stage after 10 days in Float or with voltage drop to programmable parameter.

2 Stage Type 1
Bulk Stage at constant current until desired voltage is reached, then
Absorption Stage at constant voltage for a programmable length of time, then switches charging OFF
Reset to Bulk Stage after 10 days or with voltage drop to programmable parameter.

2 Stage Type 2
Bulk Stage at constant current until desired voltage is reached, then
Absorption Stage at constant voltage; this is a de facto Float Stage.

So what does the collective wisdom say about these options? Will one be preferable for routine charging to 50% SOC when at our home dock and a different one preferred for a high SOC during trips? What are the pros and cons of the different profiles?

Thank you in advance for your input!

 

[Steve_S]

I have a EVO-4024 and most setting should be similar.
I use OPTION-5 : 2-Stage, Type 3
End Amp @ 14A for 280AH Packs.

Stage 1 – Bulk Stage (See Section 5.7.1.1)
• Charge at constant current = the programmed value of parameter “BULK CURRENT” (Default value is 40A. For details of programming range & procedure, refer to Section 4.4.2.1 of EVO-RC Remote Control Manual attached at Appendix-A)
• Transition to Absorption Stage when voltage rises to the set value for programming parameter “ABSORP VOLTAGE” (Default value is 14.4V for EVO-2212/3012 and 28.8V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.2 of EVORC Remote Control Manual attached at Appendix-A) 2. Stage 2 - Absorption Stage (See Section 5.7.2)
• Charge at constant voltage = the programmed value for parameter “ABSORP VOLTAGE”. (Default value is 14.4V for EVO-2212/3012 and 28.8V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.2 of EVO-RC Remote Control Manual attached at Appendix-A)
• Remain in Absorption Stage till the current reduces to value = the programmed value of parameter “ABSORP EXIT AMPS” (Default value is 4A. For details of programming range & procedure, refer to Section 4.4.2.20 of EVO-RC Remote Control Manual attached at Appendix-A)
• Switch off charging after the current reduces to value = the programmed value of parameter “ABSORP EXIT AMPS” (Default value is 4A. For details of programming range & procedure, refer to Section 4.4.2.20 of EVO-RC Remote Control Manual attached at Appendix-A)
• Reset to Bulk Stage under the following conditions: i. If the AC input from the Grid/Generator is disconnected and is reconnected. ii. If battery voltage falls to the programmed value of parameter “RESET TO BULK” (Default value is 12.0V for EVO-2212/3012 & 24.0V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.15

I have Bulk/Absorb set to 28.0V / (14.0V ) [3.500Vpc]
Float set to 27.5 / (13.75V) [3.4375Vpc]
Rebulk @ 24.5V / 12.3V
Under voltage sense/alarm at 22.5V (11.2v)
Undervoltage cutoff at 22.0V / 11.0V [2.750Vpc]

REMEMBER to CORRECT for Voltage drop !
Check at the Inverter Terminals AND Battery Pack Terminals with a good DVOM and correct for the voltage drop on the Inverter.
NB: The Voltage drop will be different between Charge & Discharge. SO adjust accordingly. Even a 0.2V difference can cause a BMS to trip before the Inverter/Charger or SCC do and that should not happen. The BMS is the Last Resort Failsafe as the equipment should cutoff for Hi/Lo Voltages BEFORE the BMS forces it.

Hope it helps, Good Luck.

 

[Sabre602]

Thanks, Steve! I was hoping for a response from you, knowing that you had an EVO yourself. Yup, I have your thread about voltage calibration bookmarked, and have been making good use of these voltage differentials during the testing phase on my dining room table.

OK, you run bulk at your favorite current until you hit 3.5 v per cell (14.0 v pack voltage in 12 v equivalent). You then switch to absorption, constant voltage mode at 3.4375 v/cell. To clarify, your ABSORP EXIT AMPS is 14 a?

Is there a particular rationale in selecting your EXIT AMPS? How about the choice of your voltage to re-enter bulk charging?

It has been interesting to see the voltage differentials during charging and discharging, and am gratified to see that these deltas are consistent between the two batteries that I have built. I understand that I will set the EVO with values obtained at the battery terminals plus/minus these differentials.

Thanks so much for your thoughtful response, and for the contributions that you've made in the forum.

 

[OffGridIdaho]

I have a EVO-4024 and most setting should be similar.
I use OPTION-5 : 2-Stage, Type 3
End Amp @ 14A for 280AH Packs.

Stage 1 – Bulk Stage (See Section 5.7.1.1)
• Charge at constant current = the programmed value of parameter “BULK CURRENT” (Default value is 40A. For details of programming range & procedure, refer to Section 4.4.2.1 of EVO-RC Remote Control Manual attached at Appendix-A)
• Transition to Absorption Stage when voltage rises to the set value for programming parameter “ABSORP VOLTAGE” (Default value is 14.4V for EVO-2212/3012 and 28.8V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.2 of EVORC Remote Control Manual attached at Appendix-A) 2. Stage 2 - Absorption Stage (See Section 5.7.2)
• Charge at constant voltage = the programmed value for parameter “ABSORP VOLTAGE”. (Default value is 14.4V for EVO-2212/3012 and 28.8V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.2 of EVO-RC Remote Control Manual attached at Appendix-A)
• Remain in Absorption Stage till the current reduces to value = the programmed value of parameter “ABSORP EXIT AMPS” (Default value is 4A. For details of programming range & procedure, refer to Section 4.4.2.20 of EVO-RC Remote Control Manual attached at Appendix-A)
• Switch off charging after the current reduces to value = the programmed value of parameter “ABSORP EXIT AMPS” (Default value is 4A. For details of programming range & procedure, refer to Section 4.4.2.20 of EVO-RC Remote Control Manual attached at Appendix-A)
• Reset to Bulk Stage under the following conditions: i. If the AC input from the Grid/Generator is disconnected and is reconnected. ii. If battery voltage falls to the programmed value of parameter “RESET TO BULK” (Default value is 12.0V for EVO-2212/3012 & 24.0V for EVO-2224/4024. For details of programming range & procedure, refer to Section 4.4.2.15

I have Bulk/Absorb set to 28.0V / (14.0V ) [3.500Vpc]
Float set to 27.5 / (13.75V) [3.4375Vpc]
Rebulk @ 24.5V / 12.3V
Under voltage sense/alarm at 22.5V (11.2v)
Undervoltage cutoff at 22.0V / 11.0V [2.750Vpc]

REMEMBER to CORRECT for Voltage drop !
Check at the Inverter Terminals AND Battery Pack Terminals with a good DVOM and correct for the voltage drop on the Inverter.
NB: The Voltage drop will be different between Charge & Discharge. SO adjust accordingly. Even a 0.2V difference can cause a BMS to trip before the Inverter/Charger or SCC do and that should not happen. The BMS is the Last Resort Failsafe as the equipment should cutoff for Hi/Lo Voltages BEFORE the BMS forces it.

Hope it helps, Good Luck.

This worked perfectly on my evo 1224hw.