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Home > Charge Controller Support > PWM Solar Charge Controller Support > PWM-30-UL > GP-PWM-30-UL Operation: Maximum Power Boost Technology
GP-PWM-30-UL Operation: Maximum Power Boost Technology
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Maximum Power Boost Technology™

Maximum Power Boost Technology™ (MPBT) allows you to override the normal charging algorithm of the solar controller. MPBT is designed to be used before the end of the day, if you know you will be running many loads through the night. This feature can also be used when you have just installed the solar controller, to put batteries on a boost charge up to 14.4 VDC (Flooded, AGM and LFP) (14.1 VDC for Sealed/Gel) right away.














To activate, hold the MAX BOOST Button for 3 seconds. As long as there is full sunlight present, your battery voltage will be boosted (to 14.4 VDC for Flooded, AGM and LFP; and 14.1 VDC for SEALED/GEL) for 30 minutes regardless of the battery’s state of charge.


Icons Displayed: BOOST; Battery Symbol


In older controllers, the BOOST text icon will remain on until the controller can maintain a Boost charge voltage for 30 cumulative minutes. In newer controllers, the BOOST text icon will only appear while the controller is maintaining a Boost charge voltage.


Turning boost off or boost always on


The max boost sign comes on when either an automatic (2 hrs based on a voltage drop below 12.3V) or manual boost (30 min) is initiated.  It does not come off until the battery voltage has risen to the boost maximum (I believe this is 14.4V) and is able to hold this for the specified period of time for the boost program that has been initiated  If, for some reason, the full boost charge time cannot be completed while PV current is available, the remaining time is added to the next day’s boost schedule.  


So, for example, if the user initiates a manual boost at the end of the day, and there’s not enough juice to get the battery up to 14.4V before the sun goes down, the 30 minute boost time is added to the next day’s “automatic” boost cycle when PV current is available again.  So, instead of a 2 hour boost cycle, the next day the battery will boost for 2.5 hours.


Now, the boost memory can be cleared if the user makes a “hard reset” of the controller.  However, if the battery is below 12.3V when reset, the boost symbol will stay on because the controller detected a battery voltage below the boost activation voltage.


So, the first thing to check is what the battery voltage is at when restarting the controller.  It’s a good idea to verify this with a multi-meter both at the controller terminals and directly at the battery in the event there is a voltage drop in the wires.


IMPORTANT: Do not use the Maximum Power Boost function more than twice a day as it could damage lead acid batteries due to gassing. Sustained high voltages decrease lithium battery lifespan.



  If sunlight is insufficient or not available, completing Max Power Boost may take much longer than 30 minutes from the time of the button press. Max Power Boost and the BOOST icon cannot be turned off by pressing the Max BOOST button.

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