monoblock management module (mmm)docs.balancell.com/mmm_data_sheet.pdf · monoblock management...

June, 2016 1 www.balancell.com

Monoblock Management Module (MMM) ________________________________________________________________________________________

6V MMM and 12V MMM versions

• Monitoring every 2 seconds of monoblock voltage & temperature

• 3W of passive balancing configurable for desired float

• Amount of balancing coulombs recorded and reported

• Operates from 4V to 18.6V (both 6V and 12V versions)

• Measures directly across monoblock terminals to avoid voltage drops

due to monoblock interconnects

• Oscilloscope mode facilitates monoblock impedance analysis

• Tolerant of overvoltage up to 43V and to reverse polarity connection

• Works on any pack up to 128 monoblocks

• LED indicators for balancing, warnings and status

• Communications over a single signal wire that is fully isolated

• High noise immunity communication using RF Modulated signalling

• Low power as typically uses 0.12mA at 12V (<1.4mW)

• Autonomous operation in a stand-alone configuration

• External thermistor option for temperature measurement

• Fully over-molded, insulated, shockproof (IK05), waterproof (IP67A)

and sulphuric acid proof

Description

The Monoblock Management Module (MMM) is

a per-monoblock device, with one MMM

connected to each monoblock of a battery pack.

Used in conjunction with a single Battery Energy

Meter (BEM), a complete Battery Management

System (BMS) can be implemented. The BEM acts

as a central management unit to collect

information from the individual MMMs and

distribute commands to them. The MMM is

designed to operate on any monoblock within an

operating voltage range of 4V to 18.6V. Two

versions with different balancing resistor values

are available being a 6V version and a 12V

version. The two versions only have different

balancing resistors. The MMM performs three

main functions: continuous monitoring of

monoblock voltage and temperature, measuring

and reporting monoblock voltage, temperature

and balancing current and passive balancing of a

monoblock.

The MMM is designed to be used in any pack

configuration with any number of monoblocks in

series and/or parallel combinations from 2 to

128, and bigger banks can have a split BMS’s

sections.

The MMM can capture and report an oscillogram

waveform, with a 1k sample length at a variable

sample rate from 20sps to 96ksps. This is carried

out synchronously with all the MMM’s throughout

the pack, together with the BEM, which captures

the battery pack voltage and current. This allows

detailed monoblock impedance analysis to be

performed using anything from a DC step, to the

50/60 Hz ripple from the charger, to a 1 kHz

injected signal.

By default the temperature measured and

reported is the temperature inside the MMM

itself. As the MMM is on top of the monoblock this

internal temperature is a fair indication of actual

monoblock temperature, provided it is not

balancing. An optional external thermistor can be

factory fitted to the MMM if required, and would

then be reported additionally.


The MMM provides up to 3W of passive balancing

on any chemistry. The voltage set-points at which

passive balancing occur can be fully configured.

This function can also be enabled or disabled as

required.

The module is fully over-molded and made to meet

the very harshest environmental conditions, being

completely insulated, mechanically robust, flame

retardant, waterproof and acid proof. It can

survive complete submersion in concentrated

sulphuric acid. This allows its use in most

environments including flooded lead acid

monoblocks in motive applications.

The communication between a MMM and BEM is

carried out over a fully isolated (1500V) and

floating single wire. An RF modulated signal is sent

over this wire using a proprietary communication

protocol with multiple levels of redundancy and

error checking. This was designed to deal with the

high levels of electrical noise present on large

battery packs used by industrial equipment. Large

monoblocks have low impedances, however, the

cell to cell interconnects and physical battery

layout add inductance to the battery pack. Hence

noisy industrial equipment with very high current

transients will cause the battery terminal voltage

to exhibit significant transient voltage spikes. This

necessitated the use of an RF modulated protocol

by the MMM so that it can communicate through

the noise in these environments.

The MMM offers continuous monitoring,

performed every 2 seconds, for limit conditions on

both monoblock voltage and temperature. These

limit conditions are fully configurable and if

exceeded are reported to the BEM as well as being

visibly indicated on the MMM via the on-board

LEDs. This enables immediate visual identification

of any monoblock at fault. The three limits that are

user configurable are over-temperature, over-

voltage and under-voltage.

The MMM module in monitoring mode consumes

very little power, since it is in sleep much of the

time between the one minute reporting and two

second monitoring operations. The power and

current requirements are given in the typical

performance curves section (e.g. 0.12mA on a 12V

monoblock). If monoblock voltage is below 3V then

the MMM shuts down, where it draws less than

0.1µA.

The MMMs also offer a failsafe feature, as they

continue to operate in a stand-alone manner even

if the BEM fails. In this case the balancing of the

pack continues to be performed and the LEDs

illuminate when limits are exceeded allowing

visual identification of monoblocks at fault. Putting

an intelligent MMM on each monoblock, creates a

more resilient battery bank made up of “smart

monoblocks”.

The distributed nature of implementing a module

per-monoblock means that failure of individual

MMM’s will not interfere with the operation of

rest of the system, making the BMS more robust.

Replacement of a single MMM is an easy and cost

effective fix, compared to the replacement or

repair of an entire BMS. The complete isolation of

each module also means that the battery stack can

be broken or disconnected to replace monoblocks

with no damaging effects on the rest of the BMS.

CE certification for electrostatic discharge,

radiated emissions and radiated susceptibility has

been obtained for the MMMs.

• CISPR22 (2008) / SANS 222 (2009)

• IEC 61000-4-2 (2008) / SANS 61000-4-2 (2009)

• IEC 61000-4-3 (2010) / SANS 61000-4-3 (2008)


Electrical Specifications

Operating voltage range

Valid monoblock voltage readings region 4V to 18.6V

Maximum overvoltage 43V

Reverse polarity voltage (6V MMM) -8V

Reverse polarity voltage (12V MMM) -16V

Operating temperature range

Operating temperature range -25°C to 80°C

Default monoblock over temperature warning 50°C

Balancing

Balancing Power Maximum (6V And 12V MMM) 3W

Balancing resistor (6V MMM) 22Ω

Balancing resistor (12V MMM) 82Ω

Balancing stops When monoblock voltage >18V

Balancing stops When MMM temp >85°C

Balancing resumes When MMM temp <70°C

Relative voltage measurement (MMM to MMM) Typically at 30°C, Max range -25°C to 80°C

Measurement time < 200us

Measurement synchronization between monoblocks < 200us

12 Bit ADC, Quantization of ADC 4.5mV/bit

Relative measurement accuracy Typ = +/-9mV Max = +/- 27mV

Absolute voltage measurement accuracy Typically at 30°C, Max range -25°C to 80°C

Monoblock voltage from 4V to 18.6V Typ = +/-18mV Max = +/- 36mV

Oscilloscope voltage measurement Typically at 30°C, Max range -25°C to 80°C

Sample memory, 12 bit, same range as above 1000 samples

Synchronization between all monoblocks < 4us

Sample rate 20sps to 96ksps

Total sample period (of whole oscillogram) 10ms to 50 seconds

Temperature Measurement

Reported 8 bit value range (Internal, Chip level:) -128°C to 127°C

Accuracy Typ = +/- 1°C Max = +/- 3°C

External, 10k thermistor:

12 Bit ADC, quantization of ADC TBD – implementation specific

Total accuracy TBD – implementation specific

Certifications

CE CISPR 22, IEC 61000-4-3, IEC 61000-4-2

SABS SANS 222, SANS 61000-4-2, SANS 61000-4-3

Environmental IP67A, IK05 (only module, not battery connections)


Operation

Limits: Over voltage, over temperature and under voltage limits can be set on MMM’s. The flashing pattern

is given in the table below. The temperature is based on the MMM’s estimate via its connection leads. The

estimate of monoblock temperature is adjusted to compensate for any heat generated by balancing.

RED LED

Flashing pattern Condition Default

50ms on / 450ms off = Short pulse twice a second

Over-temperature 50°C

450ms on / 50ms off = Long pulse twice a second

Over-voltage 15V

Fully on

Over-voltage and

over-temperature

15V

50°C

50ms on / 3000ms off = Short pulse once every 3

seconds

Under-voltage 5V

50ms on/ 200ms off/ 50ms on / 3000ms off = two

short pulses once every 3 seconds

Under-voltage and

over-temperature

5V

50°C

BLUE LED

Flashing pattern Condition

On power up, the BLUE LED will come on once only for 3 seconds.

NOTE: This is used to show correct polarity connection. Its absence

indicates that the device has been connected incorrectly.

Correct Initial

connection

50ms on/ 200ms off/ 50ms on/ 200ms off/ 50ms on/3000ms off

= three short pulses once every 3 seconds

Un-configured

50ms on/ 200ms off/ 50ms on/ 200ms off/ 50ms on/30000ms off

= three short pulses once every 30 seconds

Lost communication

Whenever a message for itself is received correctly, the MMM will

flash its BLUE LED once for 50ms = short pulse.

Received Message

Correctly

Note on un-configured state: If the MMM has not been configured it will flash its BLUE LED for three short

pulses, every three seconds. This is to indicate that a MMM has not yet been addressed by the BEM.


Note on lost communication: If the MMM has not received any communications from the BEM to itself for

more than 90 seconds it will flash its BLUE LED for three short pulses, once every 30 seconds. This is used to

indicate either a bad communication connection to the MMM itself, or that the BEM has stopped

communicating.

YELLOW LED

Flashing Pattern Condition

Always on, but brightness is proportional to the duty cycle of

balancing resistor. Brighter indicates higher balancing current.

Balancing

Reverse Polarity Connection

The MMM can handle a reverse polarity

connection provided it is within the nominal

monoblock voltage region. This is -8V for a 6V

MMM and -16V for a 12V MMM.

Passive balancing

Passive balancing is also called dissipative or

resistive balancing and is carried out by drawing

some current/charge/energy off a monoblock and

dissipating it as heat in a resistor. Passive balancing

is only able to sink current from a monoblock,

which is a negative monoblock current and

reported as such.

The MMM can perform up to 3W of passive

balancing. This function can be enabled or

disabled, and a variety of algorithm approaches

can be used. These approaches include a simple

on/off balancing around a single level, to

proportional, to proportional integral, to scaling all

balancers according to highest monoblock, or

maximum temperature etc.

VRIP balancing algorithm

The default algorithm used by the MMM's is

termed the VRIP algorithm and this is an acronym

for Constant Voltage, V, Constant Resistance, R,

Constant Current, I, Constant Power, P = VRIP.

The MMM is set with a balancing level and a

maximum balancing level from the configuration

tool. The maximum balancing level must be in the

region of 10-20% higher than the balancing level.

When a Monoblock reaches the balancing level the

MMM will then start to perform integral control of

the balancing current to keep monoblock voltage

constant. In other words, the balancing current will

be adjusted up or down to keep the monoblock

voltage at exactly the balancing level. If a charger

is set correctly then at top of charge the current

will be reduced to something that will not over

power the balancing. If this is the case then, as a

monoblock reaches the balancing level, the

balancing current will progressively increase, and

hence the monoblocks will receive progressively

less charge current until it has truly reached the

balance level.

The second region is constant resistance which

appears as a pure resistance connected

permanently across a monoblock, and as

monoblock voltage increases the current

increases. The third region is the constant current

region, meaning a constant current is drawn from

the monoblock as voltage increases further.

However in practice this region does have a small

positive slope, so higher voltages will draw slightly

higher current. Thus if the charger current is too

high, then the monoblocks will go into the constant

resistance or constant current region, but the

system will still have a balancing effect as higher

monoblocks will have more balancing current

drawn off them. To explain it in converse, if this

was not the case and higher monoblock voltages

drew less current once they are over the balancing

level, they are then in danger of going even higher

than the other monoblocks and the system

becomes unstable.

Provided the monoblock voltages never exceed the

maximum balancing level, the system will remain


stable as higher monoblock voltages will always

have more current being drawn off them. The

maximum balancing level is the point where

maximum monoblock balancing current and

power will occur. It is the point that the monoblock

voltage should never exceed. If the monoblock

voltage goes even higher than the maximum

balancing level and goes into the fourth region of

constant power dissipation. In this region the

MMM will go into a constant power mode to

prevent itself from overheating, and current will

decrease with increasing voltages. This is simply a

protection mechanism and in theory the

monoblock voltage should never be in this region.

However, even if it does end up in this region, the

design philosophy is that the MMM should and will

continue to draw power from the monoblock in an

effort to bring its voltage down again.

Graphs below show typical balancing levels for 6V

and 12V monoblock. More balancing examples can

be found by downloading spreadsheet to calculate

balancing currents from website.


Typical Current and Power consumption – Of MMM with no LEDs on and not balancing.

0,0mW

0,4mW

0,8mW

1,2mW

1,6mW

2,0mW

2,4mW

2,8mW

0,00mA

0,02mA

0,04mA

0,06mA

0,08mA

0,10mA

0,12mA

0,14mA

0,0V 2,0V 4,0V 6,0V 8,0V 10,0V 12,0V 14,0V 16,0V 18,0V 20,0V

Po

we

r

Cu

rre

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Cell Voltage

MMM normal current and power consumption vs cell voltage

Current Power


MMM Installation

The MMM can have customer specified connector lugs and lengths of connecting leads. Current default

standard is a M6 Lug, and wire lengths so that it is 300mm from lug to lug. It connects to a monoblock at the

normal positive and negative terminals. It is good practise to fist connect the monoblock interconnects and

then connect the MMM’s.

Communications wire Installation

The communications is done using a single wire that is fully capacitively isolated at all connection points and

hence is capable of floating at any DC voltage level. It uses the actual battery pack as a return path. Hence to

minimise noise and pick up interference the communications wire and the monoblock and monoblock

interconnects should make a “twisted pair”, or the area between them should be minimised. Please see

communications wire installation guide and video.

6V MMM and 12V MMM

These are identical except for their balancing resistor values, being 22Ω for 6V and 82Ω for the 12V. They

can be identified on the underside of the MMM by an arrow pointing towards the numbers 6 or 12, as

shown in mechanical drawings

12V MMM 6V MMM


Mechanical Layout

Dimensions in (mm) – typical lead length of 300mm. Lead length can be specified for orders (>3k).

Alternative connection lugs and wiring lengths are available in OEM quantities

monoblock management module (mmm)docs.balancell.com/mmm_data_sheet.pdf · monoblock management...

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