
MLI Ultra 12/1250 & 24/1250
Advanced Systems Group EMEA P.O.Box 22947, NL-1100 DK Amsterdam, The Netherlands. Email: info.emea@OneASG.com Web: www.mastervolt.com 10000018507/00
This Quick installation guide provides a brief overview of a basic stand-alone
installation of the MLI Ultra 12/1250 & 24/1250. Always read the complete
and installation manual in parallel with this quick start guide. Scan the QR
code to download the manual.
All electrical systems (DC and AC) must be disconnected from any power source during the entire
installation! Use isolated tools!
Always avoid short circuits, too deep discharges, and too high charge currents.
Always handle with care and lift the battery at the handle.
Never open or dismantle the battery and do not short circuit.
The Material Safety Data Sheet for Mastervolt Lithium-Ion batteries is available on www.mastervolt.com.
Read the safety instructions (chapter 1 of the user and installation manual).
Open the box. Before taking the battery out, take out the handle and insert it into the recess on the back and front side
of the battery (item a in drawing) to secure it. Now take out the battery.
a) Provision for removable handle.
b) M8 positive terminal
c) M8 negative terminal
d) Hold down edges group 31, fit battery group size 49
e) Attachment strap support (for stationary applications only)
f) Protective vent; maintain adequate ventilation around this
opening. Do not touch the membrane!
g) Auxiliary connector
h) MasterBus/CZone connectors
i) Status LEDs and DIP switch cover
j) Battery switch-button (safety disconnect)
Check the contents of the delivery. Contact your supplier if one of the items is missing. Do not use the MLI Ultra if it is
damaged.
B. 2x plain washer
C. 2x spring washer
D. 2x battery terminal M8 bolt
E. 2x battery terminal M8 Allen bolt
F. 1x automotive battery pole positive
(thick)
G. 1x automotive battery pole negative
(thin)
H. 1x MasterBus terminator
I. 1x MasterBus cable (1m)
J. 1x CZone Drop cable (1m)
K. 1x 6p auxiliary cable (2m)
L. 2x Mounting straps
M. 1x Handle
N. 1x Quick installation manual

MLI Ultra 12/1250 & 24/1250
Advanced Systems Group EMEA P.O.Box 22947, NL-1100 DK Amsterdam, The Netherlands. Email: info.emea@OneASG.com Web: www.mastervolt.com 10000018507/00
Secure the battery in place. Choose the option that best fits the position.
Mounting straps
(stationary applications only)
Hold-downs on long side (group 49)
Make sure that the charger is Lithium Ion compatible and meets the MLI Ultra's charge parameters.
Out of the box, the battery is on (switch is closed). Press the Battery switch-button to switch-off (safety disconnect).
Description of the Battery switch:
• Short press to make LED C show the status of the Battery switch.
- Solid on for 1 minute: battery is on (switch is closed).
- Blinking for 1 minute: battery is off (switch is open).
• Press for 1 second to switch-off. LED C will blink.
• Press for 5 seconds to switch-on. LED C will light up for 1 minute.
If this LED is on, a BMS error has occurred or cells are damaged. Check
the installation and contact your supplier.
During normal operation the LED is off.
SoC low. Charge the battery.
CZone network identification (during installation).
Auto cluster configuration error. See the user and
installation manual for details
Battery is executing a recovering procedure.
Battery is updating its firmware.
When the Battery switch-button is pressed short, this LED indicates the
status of the battery switch.
- Solid on for 1 minute: battery is on (switch is closed).
- Blinking for 1 minute: battery is off (switch is open).
Status LEDs and
DIP switch cover

MLI Ultra 12/1250 & 24/1250
Advanced Systems Group EMEA P.O.Box 22947, NL-1100 DK Amsterdam, The Netherlands. Email: info.emea@OneASG.com Web: www.mastervolt.com 10000018507/00
Due to the Interrupt Rating, use a T-fuse or an MRBF
fuse. In our example we use an MRBF fuse.
Directly on the battery terminal (A),
mount an MRBF fuse holder (B).
Add the fuse (C).
Add the positive cable (D).
Add a flat washer (E).
Add a spring washer (F).
Tighten the bolt.
Connect the negative cable to the – terminal.
Recommended torques: 14.7 – 19.6 Nm/130 – 170 InLbs.
Never mount a stud fuse directly on the battery terminal. Always use the
isolated fuse holder! Otherwise the fuse will not work!
* or connect directly to load or charger
A. No communication. Continue with the step 10.
B. CZone
• Set DIP switches 1 and 2 to OFF.
• Use DIP switches 3 to 10 to set the dipswitch number used in a CZone
network. At least one of DIP switches 3 to 10 must be ON.
• Connect the drop cable. On the battery side, plug the connectors into either
of the communication ports.
• Keep DIP switch 1 ON.
• Option: set DIP switches 2 to 8 to
match the required settings. See
table "MASTERBUS DIP SWITCH
SETTINGS". DIP switches 9 and 10
are not used in MasterBus.
• Plug the MasterBus cables (or
MasterBus Terminator if required)
into the communication ports.
Example of a MasterBus network
Detail of a CZone network
New out of the box, the MLI Ultra is suitable for use in a MasterBus network or as a stand-alone battery. Use the CZone
Configuration Tool or MasterAdjust for advanced settings. See the user and installation manual for details.
Press the Battery switch-button for 5 seconds to switch the battery on. LED C (green) will be solid on for one minute.
Switch on some loads and verify that they are working. Switch off the loads, switch on the charger and verify
(charger status) that the battery is being charged. The battery is now ready for operation.

MLI Ultra 12/1250 & 24/1250
Advanced Systems Group EMEA P.O.Box 22947, NL-1100 DK Amsterdam, The Netherlands. Email: info.emea@OneASG.com Web: www.mastervolt.com 10000018507/00
MASTERBUS DIP SWITCH SETTINGS
CZone communication
MasterBus communication
MasterBus powering disabled
MasterBus powering enabled
Event-based 'stop charge' can be setup per charger
Automatic 'stop charge' for ALL Mastervolt chargers
In a multiple unit configuration, one battery is
the Primary unit, the others are called replica
units.
For complex configurations, keep DIP
switches 4,5 and 6 of all units off and use
MasterAdjust to modify the settings.
Stand-alone unit
Replica unit
Primary unit in a 12V system
Primary unit in a 24V system
Primary unit in a 36V system
Primary unit in a 48V system
The Battery Management System controls
the built-in battery switch. Including switching
on again when conditions are safe.
Auto switch-on feature enabled
Auto switch-on feature disabled
If the battery is switched-off, there will be no
voltage at the poles and some
(non-Mastervolt) chargers will not start
charging.
Battery detect feature disabled
Battery detect feature enabled
See the user and installation manual for details.
SPECIFICATIONS
Bulk/absorption (max charge) voltage
Float voltage (end of charge)
Recommended charge current
Max. continuous discharge current
Peak discharge current (10 seconds)
–20 to 50ºC [–4 to 122ºF]
Charging at temperatures below -5ºC / 23ºF may result in battery not accepting
charge current.
If a charger is connected and the temperature of the MLI Ultra is below 0°C
[32°F], then the internal heater is turned on until 5°C [41°F] is reached or the
charger is disconnected. It takes about one hour to get from -20°C [-4°F] to
above 0°C [32°F].
Temperatures below 5ºC / 41ºF and above 25ºC / 77ºF may affect lifetime and
cycle life.
* Due to thermal protection, this high discharge current can be used for 3 minutes at or above an ambient temperature of 25ºC [77ºF].
Do not dispose of with normal household waste! Act according to local rules.