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What are all the issues that effect charging current?

Guda

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Any other factors?
 
Just 3 factors:

1. Charging source output voltage (during charging load)
2. Battery voltage
3. Resistance

Charging current = (Charging source output voltage - Battery voltage) / Resistance

It couldn't be any simpler.
 
1. voltage drop
Its the only thing that I encountered when charging lithium. Mainly with solar. The controllers voltage is always higher then actual battery voltage. This results in the controller not sending max amps to the battery. I notice this with 4 different controllers I tried both pwm and mppt.
 
1. voltage drop
Its the only thing that I encountered when charging lithium. Mainly with solar. The controllers voltage is always higher then actual battery voltage. This results in the controller not sending max amps to the battery. I notice this with 4 different controllers I tried both pwm and mppt.

That's a wiring thing and @Cal covered it in item #3.
 
voltage drop can be a wiring problem but on solar systems, it's usually the controller that reads high. Some can be calibrated to match the battery terminals. On my system I replaced the wires going to battery several time and currently use 10 gauge pure copper going to the battery (2 feet away) and still get a .5 volts descrepency.
If your system has voltage drop whether wire problems or miscalibrated charger, you will probably never get a full charge on your battery and max amps going to the battery.
Not too many people check for voltage drop, I never did for years when using lead acid.
 
viscosity.

FLA wants enough current to get bubbling and stirring of electrolyte
Gel wants low current.

Watts/Amps available from source!
(can't get blood from a stone)

But to answer the question you actually asked, I would have to say, "The charge controller."
(not that is is an "issue", but it is the thing that produces charging current)


 
voltage drop can be a wiring problem but on solar systems, it's usually the controller that reads high. Some can be calibrated to match the battery terminals. On my system I replaced the wires going to battery several time and currently use 10 gauge pure copper going to the battery (2 feet away) and still get a .5 volts descrepency.
If your system has voltage drop whether wire problems or miscalibrated charger, you will probably never get a full charge on your battery and max amps going to the battery.
Not too many people check for voltage drop, I never did for years when using lead acid.

That's the difference between an OCV and a voltage affected by a current and/or a poorly calibrated SCC. 10awg is laughable. I have 5awg (2x 8awg) to handle up to about 65A @ 48V. I also have a OCV battery monitor (Victron Smart Battery Sense) to give the SCC a direct OCV reading instead of the current/wiring influenced value.

Your above assertions are false:

1) Voltage drop decreases as current tapers in absorption phase. % of charge is negligibly affected.
2) If the charge controller is pushing X Amps, the batteries will receive X Amps. Period. No exceptions. Not affected by voltage drop.
 
I always advise people to size battery cable using a 1% voltage drop round trip.

Cable size calculators usually use 3% voltage drop. That's too large for main charge and discharge cables.
 
1. voltage drop
Its the only thing that I encountered when charging lithium. Mainly with solar. The controllers voltage is always higher then actual battery voltage. This results in the controller not sending max amps to the battery. I notice this with 4 different controllers I tried both pwm and mppt.
Did any of your solar controllers have separate voltage sense leads?
 
I think I could accept 3% loss at 100% load, 6% at 200% surge load. My inverter is between 91% and 96% efficient.
Lower wire resistance would be better, but once I have 2/0 or 4/0 going to the inverter I may not want to spend more on copper.
Might be different if majority of time it ran between 50% and 100% load, but mine is well below that.
That said, looks like mine is about 0.4% drop if putting out 7kW per inverter. (8' of 2/0 power and return) I was able to keep it pretty short.

For wires between PV panel and charge controller, I tend to do what is convenient or my standard selection. It affects how much power is harvested at peak times, but doesn't impact electronics functioning or motor starting.
 
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