Campbell Scientific CH201 User Manual

Revision: 12/2020

Copyright © 2020

Campbell Scientific, Inc.

Table of contents

1. Introduction 1

2. Precautions 1

3. Initial inspection 3

4. Overview 3

4.1 Communications interface 4

5. Specifications 6

6. Installation 8

6.1 Connect to power source 10

6.1.1 Solar panel 10

6.1.2 DC power 11

6.2 Connect to battery 11

6.3 Connect to data logger 11

6.4 (Optional) Connect to data logger for SDI-12 or RS-232 communications 11

6.5 Turn on power source 12

6.6 Turn on CH201 12

6.7 (Optional) Configure using Device Configuration Utility 12

6.7.1 Battery families and capacity 15

7. Operation 19

7.1 Charging algorithm 19

7.2 Maximum power point tracking 20

7.3 Communications 21

7.3.1 SDI-12 communications 23

7.3.1.1 SDI-12 commands 24

7.3.1.2 CRBasic programming 25

7.3.2 RS-232 communications 25

7.3.2.1 RS-232 commands 27

7.3.2.2 CRBasic programming 29

7.4 LED indicators 29

Table of Contents - i

8. References 30

Appendix A. Downloading an operating system 31

Table of Contents - ii

1. Introduction

The CH201 is a charging regulator for an external rechargeable 12V VRLA, valve-regulated lead­acid, battery, such as the BP12 or BP24 offered by Campbell Scientific. Charging power for this
charging regulator is typically supplied by an unregulated solar panel or AC-to-DC converter.

The CH201 is a smart charger that provides a programmable low voltage disconnect and two-step
constant voltage charging with temperature compensation for optimal charging and battery life.
A maximum power point tracking algorithm is incorporated for solar inputs to maximize available
solar charging resources.

The CH201 is a series regulator, which has the regulator placed, in series, between the charging
source and the load. As batteries become closer to fully charged, series regulators reduce the
current drawn from the charging source. The charging source may be completely unloaded if full
charge is reached. Charging source unloading is acceptable for solar panels and AC-to-DC
converters. For wind turbines, charging source unloading can cause free spinning. Consequently,
do not use series charging regulators, such as the CH201, to regulate wind-turbine outputs
without a method to load the turbine when the batteries require little or no charging current.

The CH201 has several safety features that protect the charging source, battery, charger, and load
devices. Both the DC In 1 and DC In 2 input terminals have polarity reversal protection and
programmable hardware current limits. The CH201 has a programmable maximum battery
charging current limit. A self-resettable, thermal fuse is in-series with the 12 VDC output
terminals to protect the charger from an output load fault. The CH201 includes battery reversal
protection, and ESD and surge protection are incorporated on all inputs and outputs.

2. Precautions

Only use the following battery cables with the CH201: pn34029, pn34031, pn34040, and
pn36589.

Overcharging VRLA batteries can produce excess hydrogen and oxygen gases, and the
accumulation of hydrogen gas can form an explosive mixture. Fortunately, hydrogen gas is
difficult to contain in anything but a metal or glass enclosure.

CH201 12V Charging Regulator 1

DANGER:
Never house VRLA batteries in an enclosure that does not allow dispersion of emitted
hydrogen gas.

When using a current limiting power supply such as a AC-to-DC converter, change the input
current limit using the Device Configuration Utility to prevent the CH201 from pulling more
current than what is available, thus tripping current limit protection of the converter.

VRLA batteries can provide high-surge currents. A 4.6A solid-state circuit breaker protects the
12VDC output terminals, but there is no fusing for inadvertent bridging of the battery terminals.

DANGER:
Accidental shorting of battery terminals by metallic objects, such as watchbands, can cause
severe burns due to rapid heating and is also a fire hazard.

VRLA battery manufacturers state that “Heat Kills Batteries.” While the operating temperature
range is –40 to 60°C, optimum battery life occurs in the 5 to 35°C temperature range1. The
CH201 offers temperature compensation of the battery charging voltage based on a temperature
measurement inside the CH201 case. The CH201 internal temperature measurement only
accurately represents battery temperature for charge voltage compensation if the battery is next
to the CH201. To overcome temperature differences, use the CH201 serial interface to input an
independently measured battery temperature for improved charging temperature compensation.

With rechargeable batteries, a charge → discharge → recharge event is termed a cycle. Depth of

discharge can greatly affect the battery service life. For example, limiting the depth of discharge
to 50% instead of 100% (complete discharge) will double the number of useful cycles available
from the battery. VLRA batteries last longer with less (or more shallow) depth of discharge.

VRLA batteries self-discharge at approximately 3% of rated capacity per month at room
temperature1. A 3% of rated capacity per month self-discharge results in 100% discharge in
approximately 33 months for a battery stored at room temperature. The battery self-discharge
rate increases with higher storage temperatures.

WARNING:
Leaving a lead-acid battery in a discharged state for prolonged periods causes large sulfate
crystals (sulfation) that are detrimental to battery performance.

Every few months, recharge stored batteries to prevent irreversible sulfation due to prolonged
time in a discharged state.

1

Genesis Application Manual – Genesis NP and NPX Series US-NP-AM-002, June 2006.

CH201 12V Charging Regulator 2

3. Initial inspection

Upon receipt of the CH201, inspect the packaging and contents for damage. File damage claims
with the shipping company.

4. Overview

FIGURE 4-1 (p. 3) provides a simplified schematic of the CH201 charging regulator. See Table 5-1

(p. 7) for rechargeable batteries offered by Campbell Scientific.

FIGURE 4-1. CH201 schematic

CH201 12V Charging Regulator 3

An unregulated solar panel or AC-to-DC converter typically supplies charging power to the
CH201. As shown in FIGURE 4-1 (p. 3), diodes connected to the two DCIn terminals provide input
reversal protection and isolation between power sources. DCIn terminals have a polarity that
must be followed. Connect the positive wires to the DCIn terminals, and connect the negative
wires to the G terminals. Reversed polarity inputs, however, will NOT damage the CH201. The
DCIn input terminals have an input current limit of approximately 10amps, making the CH201
well suited for 170watt or smaller solar panels. Higher powered solar panels may not damage the
CH201, but the additional power likely won't be fully used. Additionally, each input has a
programmable current limit. See (Optional) Configure using Device Configuration Utility (p. 12).

Internal diodes route power from the source with the highest input voltage. An AC-mains­powered application can use a solar panel for back-up if the AC-to-DC source has a higher
voltage than the solar panel. The solar power will be the primary supply and AC will be the
secondary supply if the solar panel has a higher output voltage than the AC-to-DC source.

The 12V output terminals are for powering a data logger and peripherals. A toggle switch
controls power to these output terminals. The total output current is limited by a 4.6A solid-state
circuit breaker.

Each battery family uses a unique charging algorithm to calculate the best charging voltage for
battery temperature. The algorithms use the charger temperature as the default temperature
source. If the charger and battery are in the same enclosure, the two temperatures will be similar.
If the battery will be in a separate enclosure, place a temperature sensor on or near the battery
and use the appropriate SDI-12 or RS-232 command to send this temperature to the module (see

Table 7-4 (p. 25) and Table 7-6 (p. 27)).

The CH201 has two LED indicators, the CHG (charge) LED and the CKBAT (check battery) LED.

Table 7-7 (p. 30) and Table 7-8 (p. 30) list the conditions and associated colors for the CHG and

CKBAT LEDs.

The CH201 communicates using a data logger or computer COM port. Data logger
communications can be done using SDI-12 or RS-232 as indicated in FIGURE 7-3 (p. 23) and

FIGURE 7-4 (p. 26). See Communications (p. 21) for details.

4.1 Communications interface

The CH201 can send data to the user to observe and manage power requirements and possible
problems. It can also be configured to work with a wide range of batteries and input power
supplies and test the existing battery system for possible shorting and sulfation problems.

The CH201 can be used without any configuration or communications. To take advantage of the
additional features of the CH201, however, the CH201 supports three kinds of communications:

CH201 12V Charging Regulator 4

l Communications to a computer running Device Configuration Utility. This utility simplifies

configuration of the CH201 and allows for operating system updates. Device Configuration
Utility may be downloaded free of charge at www.campbellsci.com/downloads. See

(Optional) Configure using Device Configuration Utility (p. 12).

l SDI-12 communications as an SDI-12 sensor according to the SDI-12 standard

(www.SDI-12.org). See SDI-12 communications (p. 23) for an in depth explanation.

l RS-232 communications to a data logger or computer. See RS-232 communications (p. 25)

for an in-depth explanation.

SDI-12 data logger programming is usually simpler than RS-232 programming. Also, multiple
SDI-12 sensors can share a single data logger control or universal terminal if they have unique
SDI-12 addresses; RS-232 devices are limited to one device per terminal. The advantage of RS-232
is its speed can be faster than SDI-12.

All CH201 serial communications use three COM terminals, TX, RX, and G. The CH201 will detect
the mode of communications and will reconfigure itself accordingly.

FIGURE 4-2. CH201 COM terminals

CH201 12V Charging Regulator 5

5. Specifications

Operational Temperaturea:

Dimensions:

SOLAR Terminals (Solar Panel
or Other DC Source)

b

Input Voltage Range:

Maximum Charging Current:

Power Out (+12 terminals)

Voltage:

Battery Charging

c

CYCLE Charging:

FLOAT Charging:

Measurements

Input Voltage:

–40 to 60 °C

11.40 x 10.08 x 3.38 cm (4.49 x 3.97 x 1.33 in)

15 to 50VDC

10 A

Unregulated 12 V from battery

4.6 A solid state circuit breaker. Self-resettable thermal.

Vbatt(T) = 14.70 V – (24 mV) • (T – 25 °C)

Vbatt(T) = 13.65 V – (18 mV) • (T – 25 °C)

±(1% of reading +15 mV)

Battery Voltage:

Load Currentd:

Battery Currentd:

Charger Temperature:

±(2% of reading +15 mV)

±(2% of reading +2 mA)

±(2% of reading +10 mA)

± 2 °C

Quiescent Current

No Charge Source Present:

No Battery Connected:

Compliance:

300 μA maximum

Typical 5 mA at 40 VDC

View the EU Declaration of Conformity at

www.campbellsci.com/CH201

a

VRLA battery manufacturers state that “heat kills batteries” and recommend operating batteries at temperatures

below 50 °C.

b

Battery voltages below 8.7 V may result in <3.0 A current limit because of fold-back current limit.

c

Two-step temperature compensated constant-voltage charging for valve-regulated lead-acid batteries. Cycle and

float charging voltage parameters are programmable with the default values listed.

d

Impulse-type changes in current may have an average current measurement error of ±(10% of reading + 2 mA).

CH201 12V Charging Regulator 6

Table 5-1: Available Campbell Scientific battery packs

Operating

Battery Pack Model

Amp-Hour Capacity

Temperature Range

1

Battery Family

(Ah)

(ºC)

Charge: –15 to 50

BP7 7

EnerSys/Genesis

Discharge: –20 to 60

Charge: –15 to 50

BP12 12

EnerSys/Genesis

Discharge: –20 to 60

Charge: –15 to 50

BP24 24

EnerSys/Genesis

Discharge: –20 to 60

BP84 84 –40 to 71 Concorde Sun Xtender

1

Battery specifications are from the manufacturer. The CH201 contains charging algorithms that optimize battery
charging over the range of –40 to 60 °C. Battery usage outside of manufacturer specifications could have unknown
effects on the life of the battery.

WARNING:
Battery life is shortened if the battery is allowed to discharge below 11.5 VDC. Low voltage
disconnect can be set in the CH201. Default low voltage disconnect is 6 VDC.

Charging requirements and tips:

Campbell Scientific offers a variety of solar panels and AC-to-DC transformers to meet the power
requirements of a system installation.

l 10 A is the highest input current that the CH201 can fully use. Although a solar panel or

transformer with a higher output current won't damage the CH201, its power will not be
fully used. Peak voltage of the solar panel must be less than 50VDC.

l Solar panel specifications assume a 1 kilowatt per square meter illumination and a solar

panel temperature of 25°C (77°F).

l Individual solar panels may vary up to 10%.

l Solar panel output voltage increases as the panel temperature decreases. VRLA batteries

also have increased output voltage as the battery temperature decreases.

l Higher latitudes and less sun hours during winter months might require a larger solar panel

than what is required to keep the battery charged during the summer.

l Use the Device Configuration Utility to change the current limit settings of DC In 1 or

DCIn2 to accommodate the current limit of a charging source. For example, set the

CH201 12V Charging Regulator 7

current limit to 1.67 A to avoid tripping the power supply when using a wall charger with a

1.67 A current limit.

DCIn terminals have a polarity that must be followed. Connect the positive wires to the DCIn
terminals, and connect the negative wires to the G terminals. Reversed polarity inputs, however,
will NOT damage the CH201.

6. Installation

The CH201 module is designed to handle extreme conditions and to transmit charging, load, and
battery voltage and current information directly to a data logger by using SDI-12 or RS-232
commands. The data logger program can use the CH201 data to calculate a power budget for the
system and remotely pinpoint power problems. SDI-12 or RS-232 connections are not required for
normal operation, and the module is ready to use out of the box.

The CH201 has mounting holes on one-inch centers for mounting to a standard Campbell
Scientific enclosure backplate—see the enclosure manual for mounting suggestions. See FIGURE

6-1 (p. 9) for a typical enclosure installation using a CH201.

NOTE:
By default, the CH201 module is programmed with a battery capacity of zero amp-hours (Ah).
This sets the charger to charge at a lower current rate. A battery capacity must be configured
into the CH201 to enable the more aggressive two-step constant voltage charging scheme.
See Battery families and capacity (p. 15) for making changes by using Device Configuration
Utility. A downloadable example program using SDI-12 to set the battery capacity is available
at www.campbellsci.com/downloads/ch201-program-examples.

CH201 12V Charging Regulator 8

FIGURE 6-1. CH201 configured for SDI-12 communications

The installation section discusses the following:

6.1 Connect to power source 10

6.2 Connect to battery 11

6.3 Connect to data logger 11

6.4 (Optional) Connect to data logger for SDI-12 or RS-232 communications 11

6.5 Turn on power source 12

6.6 Turn on CH201 12

6.7 (Optional) Configure using Device Configuration Utility 12

CH201 12V Charging Regulator 9