How to Charge Lithium Batteries, w/o BMS Comm.

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How to Charge Lithium Batteries, w/o BMS Comm.

In the present blog, we highlighted a step by step installation guide how to set up the lithium batteries if your off-grid or hybrid inverters do not have a BMS system. The following procedure is necessary for an optimum charging process.

The LCD displays and inverter setting are corresponding to our off grid 5kW and 5kW hybrid solar inverter. This article is only valid for inverters with manufacturing date 2018 or older. The production from 2019 onwards includes a special software for establishing communication with the Battery Management System (BMS) of Pylon US200, US2000B, US2000 Plus

Conversol S1 off grid 5kW – Set up

The LCD below appears on the 5kW 48V Conversol (also known as MKS-48V, MPPT). The user defined battery is available in the menu 5.

LCD display of Conversol MKS Axpert solar inverter.

You have to follow the below instructions in order to charge the US2000 or Phantom Pylon Batteries correctly and at the right current ratings.

  • Connect the inverter to the battery to start up the system and power up the screen.
  • Press Enter for 5 sec to enter the settings of the inverter
  • Press ‘Up’ and ‘Down’ to choose the setting item No., press ‘Enter’ to enter into the detailed setting parameter, when finish press ‘Enter’ again. The following setting items need to be set follow the recommended value:
Program/MenuSettings required for US2000
Program 02Set to N*25A, N=battery amount
Program 05Set to USE
Program 12Set to 48V
Program 13Set to 51V
Program 26Set to 53.2V
Program 29Set to 47.5V

Table 1. Important charging parameters for lithium in US2000 batteries.

Three major settings for charging the batteries correctly

  • Set bulk charging voltage
  • Set float charging voltage
  • Set low cut-off voltage
Conversol MKS 5KW Menu for Battery Settings
Entering the menu for user defined lithium battery charging

Note: Axpert/Conversol Inverter can only be powered up via battery, if the battery is turned off due to over-discharge, over temp. or other reasons, in order to wake up the inverter you need turn on the battery manually.
Any further questions to this SOP please contact us via

Range of charging voltage: Bulk/Floating/ Low DC Cut Off

Table 2

Charging with Compatible BMS System – Conversol V5

Having a compatible inverter with Pylontech batteries, it simplifies the installation procedures and does not require any software adjustments.

The following diagrams illustrate the connection of lithium batteries to our Conversol V5 inverter/charger. This particular model has a built in communication protocol with the BMS of US2000. Using the right RJ45 ethernet cable (provided with the inverter), the user should not make alter any settings. The charging, discharging and equalization processed are managed automatically by the BMS.

Table 3: Energy stored and minutes of consumption with 50% (2500Watt) and 100% (5000Watt) load.

The above table is a useful tool that help you to understand how much storage is required according to the back up time. We took into the the 80% depth of discharge (DOD) as worst case scenario . A battery of 2.4kWh has actually 1.95kWh usable energy every day.

No. US2000 BatteriesUsable Energy (kWh)
2 3.9kWh
3 5.85kWh
4 7.8kWh
5 9.75kWh
Maximum No Batteries
Without communication hub.

Table 4. Back up time with lithium blocs from 2 to 8 in parallel.

Voltasol Hybrid 5.5kW inverter-Set up

Table 5. Back up time with 50% and 100% load using Hybrid inverters. The values are quoted for the entire range of Infinisolar and Voltasol Hybrid 3kW, 5.5kW, 5kW and three phase 10kW.
Designer and developer of solar photovoltaic systems from 1kW to Megawatt range. Steve worked for Alstom and General Electric for 11 years. He develops solar inverter and complete systems with energy storage that are affordable, easy to install, and have a quick return on investment.

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