According to the wire gauge calculator I use, 60 amps over 50' (round trip distance) @ 12v would have a 6.39% voltage drop. That exceeds the 3% threshold that most of us shoot for.
Keep in mind that 60 amps is the max OUTPUT of that charger. It could very well be drawing more than 60 amps to perform the charge.
Agreed. But the 60A is, as stated, the output current, max 750W for the renogy.
The input current might be higher, depending on the voltage. If the input is 'only' 10V, the booster will still work, but it will draw more from the primary side. At 10V, assuming at max of 750W, that would be 75A or so.
4AWG has no problem to handle that, even 6AWG would do.
Yes, you will have a higher voltage drop, probably more than you've calculated (since you have caluclated at 60A). But from a cable point of view, that can handle it without any issue.
Using proper wire gauges is done for few reasons
- Limit the voltage drop to prevent issues (low-voltage cutoff eg with high inrush currents). Doesn't apply in this case, the DC-DC will compensate for the voltage loss (on the primary side of the DC-DC)
- Prevent overloading of the cables (heating up). Yes, that's true, but to a certain amount. Low voltage cables are generally WAY oversized from a point of heat/current carry capability. 14AGW can run 15A without any issue of heating, but you won't do so because of the voltage drop.
Low voltage = a low drop will still be pretty noticable: 1V drop at a 120V circuit? No-one bothers.. 1V drop at 12V.. that's almost 10% drop.
- Limit cable losses... Voltage drop x current = watts of lost power. If you have situation where every amp counts, it might be worth limiting the cable losses.
For this application 4AWG @ 25FT input, 4AWG@ 1FT to the battery, I don't see any issues. Cables are plenty sufficient.
280Ah LFP should easily handle the 60A charge, assuming it's not already full off course.
- Is the BMS able to handle 60A charge current? Some BMSses have lowerr charge current than their rated discharge current
- Are all connections done properly? Continously 60A requires decent terminals, lugs, nuts and proper torquing. IR thermometer might be usefull, FLIR camera would be awesome.
If you have any other charging options you might check if you're able to push 60A into the battery (Eg 1 or multiple regular AC chargers and solar combined). That would make sure the batteries are accepting 60A charge and you know the issue is somewhere near the DC-DC