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I have two of the same MPPT 75/15 Controllers, one of them goes to absorption mode way before the other, which means I get to my batteries being full at a slower pace.
The settings are both on factory default.
Is there a reason why this is happening and is there a solution to have them both keep running until my batteries are full.
**One controller has 2 panels conected in series
**The other controller has 2 panels connected in parallel
Hi @Andrew84,
that's because the MPPTs don't know of what the other is doing. So they need to talk together.
One way to achieve this is by using VE.Smart Networking, where the MPPTs are networked and talking to each other for synchronised charging.
More about that here: VE.Smart Networking
What is the battery voltage when one is in bulk and one is in absorption. If the battery is at the absorption voltage when one is in bulk and one is in absorption then the batteries will not charge any faster. If you get them synchronised then both will go into absorption at the same time. For lead acid batteries, as long as you are at absorption voltage the batteries control how fast they charge.
for example, if the batteries were taking 30A in bulk, 15A from each controller. When absorption voltage is reached one goes into bulk and a little while later the batteries are taking 28A, one charger in in bulk at 15A and the other is in absorption at 13A. That is as much as they will take, absorption is constant voltage, reducing current. If you get the chargers synchronised, then when the absorption voltage is reached, both will go into absorption and the current on both will reduce. In the example, when the batteries are accepting 28A, then both controllers will be supplying 14A in absorption.
