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Charge Time

BattleAxe

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Joined
Jun 20, 2022
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I'm trying to figure out what are the parameters that limit charge time on a LiFePo.

Specifically if I get a

EG4 Lithium battery 51.2V (48V) 5.12kWh with 100AH
coupled to a
EG4 3kW Off-Grid Inverter | 3000EHV-48 | 3000W Output | 5000W PV Input | 500 VOC Input

Charge time hooked up to my 7,500kw inverter generator?

Charge time hooked up to say 1,500 watts of PV panels?

or is it all controlled by the output of the charge controller regardless of it's source?

I haven't been able to figure this one out....

Thanks in Advance!! B
 
You can use kWh or Ah and insolation.

Gen: 5.12kWh / 7.5kW = 0.68 hours
PV: 5.12kWh / 1.5kW = 3.4 hours

or charging from any source at 30A:

100Ah / 30A charging = 3.3 hours

The above are approximate. It's unlikely the inverter can utilize the full 7.5kW of the generator for charging. Some of the options are configured independently, e.g., AC charging may be limited to 30A. If that's the case, 100Ah/30A = 3.3 hours.

If MPPT output is 80A, 100Ah/80A = 1.25 hours

Of course, you may never get 1.25 hours of 80A output unless you have an over-sized array.

You can also look at it in terms of daily production. Use PVWatts to determine your solar insolation for your location and multiply that by 1.5kW.

Let's say you get 4 hours of insolation, that's 4 * 1.5 = 6kWh/day.

5.12kWh/6kWh/day = 0.85 days, or 85% of your daily solar output to charge your batteries.

The above is further restricted by your specific unit specifications. Some may have an upper limit from AC, from PV and combined.
 
Let me revisit this...

AIO (EG4 3000W)
Rated Power:3,000W
Max PV Input:5000W
Battery Voltage:48V
Max Charging Current:80A
Max MPPT Operating Voltage:500VDC
Rated AC Output Power:120V

Panels
If I have these 6 panels wired in Series
Wattage:330W
VOC:46.2V
ISC:9.38A

I am theoretically producing
1,980 watts
277.2 volts
and 9.38 amps

What is the output of the AIO to the battery?

I guess what I'm hung up on is if I am only putting out 9.38 amps does the AIO boost that amperage and if so how much? Or would I need to run 2 strings to double the amp?
 
Max charge current of 80A is the absolute limiting factor, and the output depends on battery voltage.

80A * 57V = 4560W
80A * 48V = 3840W

In your theoretical situation, the volts and amps of the panels are irrelevant provided they meet the input specs.

Your output to the batteries is... 1980W - minus any inefficiencies.

The output to the batteries would depend on the battery voltage, e.g.,

1980W / 48V = 41.3A
1980W / 57.6V = 34.4A

MPPT are DC-DC converters. They take high voltage, low current input and output to battery. Power in = power out.

V_panels * I_panels = V_battery * I_battery

V is voltage, I is current in Amps.

When considering what is actually going into the MPPT for power, you use Vmp and Imp.

Voc and Isc are used to establish worst case conditions for design purposes.
 
Max charge current of 80A is the absolute limiting factor, and the output depends on battery voltage.

80A * 57V = 4560W
80A * 48V = 3840W

In your theoretical situation, the volts and amps of the panels are irrelevant provided they meet the input specs.

Your output to the batteries is... 1980W - minus any inefficiencies.

The output to the batteries would depend on the battery voltage, e.g.,

1980W / 48V = 41.3A
1980W / 57.6V = 34.4A

MPPT are DC-DC converters. They take high voltage, low current input and output to battery. Power in = power out.

V_panels * I_panels = V_battery * I_battery

V is voltage, I is current in Amps.

When considering what is actually going into the MPPT for power, you use Vmp and Imp.

Voc and Isc are used to establish worst case conditions for design purposes.
Thanks!!!!
 
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