Untouched this generator outputs 52.5 vdc
That won't fully charge a 48V lead acid battery, but perhaps that wasn't the intent.
Natively the auto start is programmed to only start running at 48 volts, and it turns it self off when telecom cabinet reaches 53 volts.
Well, that might be what you want, actually.
I don't think you want the generator to run so long as to fully charge the battery. It is sufficient for it to charge the battery up "enough" to keep the system running, and then turn off and let the system run on battery power. If the battery depletes down to 48V, start up again. You don't want to waste fuel going to 100% SoC if the sun will do that work for you later.
A 16S LFP reaching 48 volts is 3.00 volts per cell and is nearing the end of charge but still well off the safe end of 2.5 volts per cell. So that makes a pretty good generator start trip point.
At 53 volts, that is 3.31 volts per cell and LFP is decently charged at that point, enough that turning off the generator might be okay. It could stand to be a bit higher, maybe 54 volts, but not much higher.
When the sun comes out and you have solar, then the batteries can be charged to the max SoC. This saves the most fuel.
I don’t think the telecom people actually cared about the batteries being charged by this generator. It was more of an alternative power source when the backup batteries were depleted and they would be charged back by the shore chargers.
Exactly. Generator was there to prevent shutdown, not so much to replenish the batteries, though they would do that to some degree and cycle on and off.
Weird other question. Inductively I’m only showing about max 50 amp draw dc when the generator is running with pretty discharged batteries.
7.5kw/56 volts should be a lot higher amp draw right?
They may have designed the system to run at a particularly efficient operating point which was less than full power.
Or your setup just can't eat more power than the 50 amps.
Try just running it as it is and see what you get when tied to the battery bank. You might find that it does the job well enough and saves fuel over any other configuration. The telecom folks are not dummies so they probably know a lot about keeping such things operating efficiently.
Mike C.