How Hot Temperatures Affect the Vandoit Lithium Power System

How Hot Temperatures Affect the Vandoit Lithium Power System

Confirmed Issue:
High temperatures during hot summer weather can impact the Vandoit lithium power system, leading to a shutdown of the Combimaster Inverter and/or other disruptions to the power system.

Affected Units:
Vandoit vans with the Mastervolt lithium power system

Issue Explanation:

To begin, what one first needs to understand is that maintaining your lithium system does not solely include the batteries, but the entire Mastervolt management system. The Mastervolt system used in your van includes the Mastervolt CombiMaster 120V series (Inverter/charge controller),  ML-RBS Remote Battery Switch (controls flow of power in and out of the battery),  Mac Plus (Charges from alternator), and MLI Ultra 12/2750 or 5500 Lithium Battery Series (Lithium Batteries). Each of these components has a different operating temperature:
 
Component Operating Temperatures:
CombiMaster:  14°F to 140°F  
ML-RBS Remote Battery Switch: 14°F to 140°F
Mac Plus: -4°F to 140°F  
MLI Ultra Lithium Battery: -13°F to 122°F <--- (Lowest Threshold Temperature)

A few notes about these temperatures:
  1. The Mac Plus will begin to derate above 104°F.  This means there will be a reduction in output power depending on ambient conditions.  Derating serves to protect the Mac Plus from harm, thus increasing reliability and life expectancy of the component.
  2. These operating temperatures are distinct from the ambient temperature of the air in the van. 
  3. Temperatures above 77°F may affect the lifetime and cycle life of the battery.

According to Mastervolt's website, "When charging the battery, the exact charge voltage is of the essence. The charge voltage must be adjusted to the temperature of the battery. When the battery is cold, the charge voltage must be slightly higher to charge the battery fully. In high ambient temperatures the charge voltage must be reduced to ensure the battery is not overcharged. Mastervolt battery chargers are set as standard to a battery temperature of 25 °C (77° F)...  At 50 °C (122° F) the charge voltage will be reduced to 12 or 24 V to protect the battery in these high temperatures."  (Please note that your batteries are 12V, not 24V.)

Resolution:

If the Mastervolt Combimaster shuts down due to high temperatures, about 50% of the time, it can be reset simply by plugging the van into shore power.  The other 50% of the time, the inverter will need to be manually reset by doing the following:

1. Unplug the van from shore power.

2.  Underneath the Combimaster Inverter, there is a black toggle switch marked "On | Charge only" (see photo below for reference).  Switch the inverter into "Charge Only" mode.  (You may need to remove a panel below the inverter to access this switch.)

3.  Plug the van into shore power again.

4.  Switch the inverter back to "On" mode. 




If you do not have access to shore power, the following steps can help with charging the batteries via the Mac Plus.

1. Start the van's engine

2. Make sure all vents in the cargo area are open

3. Turn On the air conditioner at the overhead passenger controls to full power 

4. Remove the plexiglass in front of the battery, Combimaster, and Mac Plus (This will allow the interior temperature of the van to cool, which will allow the battery and Combimaster temperatures to cool faster)

If the above steps do not bring the CombiMaster Inverter back online, please reach out to the Vandoit Customer Support team by submitting a ticket through the Customer Support portal or emailing support@vandoit.com.