battery bank inverters lxi

[davidbrady]

Hi Kevin,

Great to hear from you. Tell us more about your Li-Ion's. What if any battery management do you use? Do you keep them in a temperature controlled basement bay? I've been reading some real world longevity studies that show temperatures swings can impact life time and number of cycles. One of the big draws of the more expensive Li-Ion's is drastically increased number of cycles but in the real world I'm not so sure.

I believe our dual Trace/Xantrex inverter/chargers have the same behavior that you describe with your Magnum's. If the batteries are deeply discharged then both chargers jump into the constant current bulk phase, as the voltage nears the constant voltage threshold one usually prematurely transitions to the absorption phase. This prolongs the bulk phase. The amount of time that each spends in the absorption phase also varies. At some point the dominant charger becomes apparent and the other prematurely moves to float stage. This is my gripe; they don't move in lock-step thru each stage, but they both definitely charge. With the hybrid nature of mine it can mean that one actually starts to lower the voltage by going into inverting and syncing with the grid!

Exasperating this phenomenon is the lack of a high impedance voltage sense wire. The Xantrex/Trace measures the voltage level of the battery bank using the same 4/0 cable that it uses for charging. The voltage drop, capacitance, inductance, ripple voltage, and impedance of this cable makes it impossible to accurately gauge the true voltage at the bank. If the chargers are to behave in sync then they both need a good independent, clean, high impedance sense line. Does the Magnum have such a line?