#565 in Battery chargers & accessories
Reddit mentions of uxcell New BIG-Size Voltage Converter Regulator DC/DC DC 24V to DC 13.8V 40A 552W Buck Transformer Waterproof
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Reddit mentions: 2
We found 2 Reddit mentions of uxcell New BIG-Size Voltage Converter Regulator DC/DC DC 24V to DC 13.8V 40A 552W Buck Transformer Waterproof. Here are the top ones.
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Waterproof IP68 Voltage Converter Regulator DC 24V to DC 13.8V 40A 552W.Protections: Over-load, Over-current, Over-temperature, Short-circuit, Over-voltage.Auto-recovery when device is back to normal operating; high transfer efficiency of 95% max..Die-cast aluminum shell, anti-shock, and moisture-proof and has stronger durability.Widely used in bus, cmb, large trucks, motor, solar generate electricity, display screen of bus and taxi, car audio deviceNote: It is recommended to use stable DC power for the input power supply If you use the pulsed DC power provided by the generator, please filter it with capacitor before connecting it to the converter. If you use solar panel to supply directly, please note that the open circuit voltage of the solar panel cannot exceed the maximum withstand voltage of the converter. The supply voltage should be within the rated voltage and always leave a certain margin.
Specs:
| Size | DC 24V to DC 13.8V 40A |
Panel wiring:
I see your point about the partial shade. It's a difficult call on a vehicle like this if you can only fit 3 panels. The panels should though, have bypass diodes in them and the Victron MPPT tracking should compensate for the change in Maximum Power Point pretty well.
Check that your Victron controller accepts the 6 AWG on the screw-down terminals.
Check that you can get MC4 connectors that somehow fit 6 AWG. Most won't. Usually the max is 8 AWG, more commonly 10 AWG. You do not want to cut the MC4 connectors off your panels. You want to use MC4 connectors.
You may have to do a roof-top junction box where you take each panel into a combiner on the roof with 10 AWG wire, and come out with 2 x 6 AWG (+ and -) wires.
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Controller sizing:
>IF I did go to 4 panels and 2S2P Whats the Volts/Amps? Double? So 75v~/17a~? so the 100/50 would be good but I could drop down to 100/30 and save a bit of $?
No no no no.
Your panel voltage would double, for the 2 in series. You'd then have 2x the current rating of 1 panel, because those two strings are in parallel. So you'd be looking at about 75 volts at 17.333 Amps.
The controllers are rated for OUTPUT not the input. Your battery bank voltage is what's going to affect how much power you can shove through with your controller's amp rating.
Changing your panel input configuration doesn't change the amps out to the batteries. That's just 'Panel-Watts / Battery-Bank-Voltage'
If you went to a 24 volt battery bank, you could downsize the controller to the 100/30. This will mean changing your inverter to a 24 volt model though.
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Battery Bank Voltage:
While it'll allow you better upgrade paths without replacing your inverter, etc. in the future, I do need to note that it looks like you have 60 cell panels; These aren't generally enough to charge a 24 volt lead acid bank to full in the peak heat of summer.
If you switch to a 24 volt battery bank, you MUST also switch to either all 3 in series or a 2S2P config with 4 panels.
This may be the only deal-breaker switching to 24 volts for you.
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12 volt step-down converter for switching to 24 volt battery bank:
Unless you're ordering from weird places, or need a particularly large step-down converter... the 24 - 12 volt converter should be ~$30 or there about.
https://www.amazon.com/uxcell-Converter-Regulator-Transformer-Waterproof/dp/B01LY8D7U0/
If you call / email the place you ordered the inverter from, you should be able to change it out for the 24 volt model, no?
I'm sorry - I totally forgot to mention the failure mode. It says engaged, and the circuit stays closed.
The make and model of the converter is uxcell (cheap Chinese, but somehow quiet and working fine). I did put a CPU fan on it and a DS18B20 temperature sensor in case it gets too hot - so far, virtually no change from ambient.