switching charging modes

[n6djr]

I have a MagnaSine MS2024PAE charger/inverter running a 24 volt system using lead calcium batteries. We had several days of overcast and the system shut down as it should have once it reached 20 volts. I fired up my AC generator and the unit immediately went into bulk charging mode. My charger automatically switches between 4 charging modes depending upon the DC voltage, but after two hours the unit never went into absorb charging mode. Is this normal? How can I be sure the charger/inverter is functioning normally? What tests can I perform and what instrumentation is required?
Thank you in advance for responding to my inquiry.
~Christian

[Sunking]

OK what you did is completely discharged your battery, something you should have never done. You have a generator to prevent that from happening. What you see is normal. and expected. Your charger will stay in Constant Current (bulk) until the battery is charged up. Just simple math. If you have a 200 AH battery completely discharged, and charge with 10 amps will take a minimum 20 hours, plus another 6 to saturate with Constant Voltage (absorb) .

You do not want to discharge more than 50% DOD or never go below 24.2 volts. Going to 20 volts does irreparable damage.

In addition you really need to run the generator once a week for several hours to fully saturate your batteries as solar cannot fully charge your battery leaving them in a Partial State of Charge a.k.a PSOC. Leaving Pb batteries in a PSOC is a recipe for dead batteries.

[Mike90250]

Here's one mfg's timeline chart for a charging profile. The Bulk stage can take many hours - depending on the amount of charging power and the depletion of the battery. Once Bulk completes (there is no time limit in Bulk, which continues until the Absorb voltage is reached), then the Absorb Stage Timer starts counting. In the winter, with longer discharge time, and shorter recharge time, it's common to get into a deficit charge condition (using 7439 watt hours and only being able to replace 4382wh in a short day) To conserve generator fuel, you add more solar panels to your array until your system is balanced.

MS_charge_stages.png

[n6djr]

Thanks Sunking and Mike. I'm learning all this as I go along. So yesterday I ran the generator for eleven hours total. After five hours of bulk charging the charger switched into absorption mode. After two hours of absorption charging the charger then went into float mode. According to my charger/inverter docs, after four hours of float charging it should have switched into 'battery saver' mode, which it failed to do. Overnight I used negligible power and this morning the battery bank measures 24.4 volts which is low. Does this sound like dead batteries?

I learned my lead calcium batteries are fourteen years old. My MagnaSine MS2024PAE charger/inverter unit has no remote control and I assume the prior owner/installer of the system ran the unit all those years with factory settings unchanged. Should I try another round of charging?

Thank you for your attention and instruction!

[Mike90250]

Do you have any way to monitor the power from the generator and from the solar ? Running the generator past bulk and more than 30 min in Absorb, will cost you a lot of fuel.
Many folks have under-paneled their solar, and are deficit charging their batteries daily,

However, having a 14 year old working battery bank says something was done right in the past. much past 10 years is outstanding.

When the weather is bad, is the time to run the generator, you do not want to bleed your batteries way down, it will kill them quickly. charge the batteries thru Bulk and a bit into Absorb and let the solar charging finish them off. $10 of fuel can save a month of battery bank wear and tear.