Magnum 4448 charger/inverter

More or less, charging runs from 5% to 13% typical for solar panels. And genset charging generally runs from 10% to 20% (or even 25%)--With 13%+ rate of charge recommend having a remote battery temperature sensor and/or you monitor the bank temperature and make sure it does not get too hot...

Also, Flooded cell batteries take high charging current at ~80% or less state of charge--And charging is pretty efficient (little charging current changes into heat/gassing)... Above ~80% State of charge, the FLA battery is roughly at the charging setpoint (absorb stage) and gradually reduces charging current acceptance... Over 90% to 100% state of charge, much of the energy turns into gassing and heat (EQ charging is mostly gassing and heating, with the "low cells" slowly being charged. Nominally 5% rate of charge for EQ charging--And even that can overheat the battery bank if done for hours on end.

So--It looks like your inverter has a default of 60 Amps... And you can change that from 100% to a lower XX% charge rate... For a 450 AH battery bank:

• 10% * 450 AH = 45 Amps
• 13% * 450 AH = 58.5 Amps
• 20% * 450 AH = 90 Amps

So--For your 450 AH, you are just over 13% rate of charge--So there is no reason for you to back the charging current below 100% (assuming your genset/utilty circuit can handle the charging current on the AC side)

But I have a question about how the Magnum uses the XXX AH capacity... Looking at the manual:

https://www.solar-electric.com/lib/wind-sun/Magnum-MS-PAE-Manual.pdf (page 37)
That is a "different" way of using "AH"... Guessing if "600 AH" = 120 minute absorb, then "400 AH" = 80 minutes for absorb time(?).

Generators are usually not very efficient during the end of Absorb cycle (low charging current, low generator loading, inefficient fuel usage at less than ~50% of genset rated load).

So, I would look at how you need to use the genset/solar/battery bank... Normally, use the genset to bring the state of charge to ~80% or so, then let the solar do the final charging (save fuel/genset runtime)... Or, if no sun for rest of day, start the genset the next day by 50% state of charge and bring back to ~80% again... You can easily do this for days on end (FLA batteries do not like to sit below ~75% SoC, but cycling is OK).

On solar, usually suggest that Absorb timer (if used) is set to ~2 hours for shallow discharges, and upwards of 6 hours for cycling to 50% SoC... It does not sound like the Batt AH setting is going to do anything bad to your batteries if you start with 600 AH setting...

Just monitor your battery bank specific gravity and try to get >~90% SoC once or a few times a week. Don't try for 100% SoC every day--That is really hard on your battery bank. Gassing (and "hot battery" from EQ and >90% SoC charging) erodes plates/causes positive grid corrosion, water usage etc.).

At least, that is how I understand the issues...  Others may have better understandings.

-Bill