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jon-2 asked

Maximizing Charging Rate

I am designing a system for an off grid application. Power for the battery bank will be provided by a generator. Not planning on using solar, as the generator is temporary until utility power is installed. Hence, the use of quattros. I would like to maximize charging rate of the battery bank while utilizing the max output of the generator (20kW) to minimize generator run time. Planning on using 100A Lithium batteries, which have a charge rate of 50A each. Planning on 8 of them for now, which should provide power for at least 12 hours to the load (800 watts, 240V) until they need recharged. If anyone has some advice on how to maximize the system that would be great. The quattros have a charge rate of 150A each, which would get me 300A for the 2, and current battery bank can accept 400A, the battery bank may be increased in size in the future.

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MultiPlus Quattro Inverter Chargerbattery chargingLithium Battery
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2 Answers
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JohnC answered ·

Hi @Jon

There's not much you can do to to 'maximise' things, the Quattros will satisfy loads then charge to their rated capacity. And that's it!

It seems you've done your calcs using 12V. 8x in parallel (and more to come) isn't really the best way to configure the batts, and I'd suggest you consider 48V strings (2 of). That'll give you 200Ah @48V, and 100A max charge.

There are no Quattros with 150A charge spec, and you don't mention whether it's 230 or 120V units you're considering. But if you look closely at specs of 12V vs 48V Quattros of the same size, you'll get more charge Watts from a 48V unit than a 12V.


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jon-2 answered ·

I did mistype, I was planning on running 48V strings, and did later realize I was wrong on charge rate. The issue is that we are trying to minimize the run time of the generator while also utilizing the at least 85% of the generators' capacity when it is required to run to charge the batteries. One of the things I was looking at was switching to the 24V Quattros, so I can run a 24V battery bank and use the Skylla-I battery charger to add additional charging current. It won't be as beneficial if I am only running the generator at 10% load during recharge, the generator will have to run much longer than if it was running at 85% load.

My using at least 85% of the generator capacity it will also fulfil the load bank requirement, lowering maintenance costs, and less run time will also help with this.


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