diy solar

diy solar

nevermind

stevelex

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Feb 6, 2020
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Ok, basic question:.

I have 3 devices connected to my 24 volt LiFePO4 battery.

1) 3000 watt 24v inverter - 200amp fuse on the positive side between it and the battery
2) EPever 40amp mppt charge controller - 50 amp breaker on positive side between it and the battery
3) 24v to 12v step down transformer (40watt) and then to a 12v fuse block for loads - was planning on a 40amp breaker, but now not sure.

The question relates to the step down transformer and the 12v fuse block. In Will's diagram on this page (https://www.mobile-solarpower.com/4000-watt-24v-solar-system.html) : there looks to be an inline fuse between the transformer and the battery (he says to ignore the battery protect, which i do not have).

In the 12v diagram (https://www.mobile-solarpower.com/the-classic-400-watt-rvs-vans-buses.html), the fuse block shares the main fuse and does not have it's own.

For all wiring I am using 1/0 between the battery/fuses/devices above because I bought 20 feet of it and unless there's a reason to use smaller wire, I'm just going to use 1/0. I'm using 10 awg for all loads.

Questions:

1) Should the step down transformer be connected to the battery through it's own 40amp breaker or directly through the main 200amp fuse? The wire on the step down transformer seems small to me.

2)Should I upgrade to a 60 step down transformer, which allows for thicker wire?

3) Does there need to be a fuse between the 12v output of the transformer and the fuse block (I would think not because there are fuses on each circuit that originates at the fuse block), but I'm not sure.

4) Can the main fuse be a breaker instead of an ANL fuse?
 
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Questions:

1) Should the step down transformer be connected to the battery through it's own 40amp breaker or directly through the main 200amp fuse? The wire on the step down transformer seems small to me.

-Yeah, I would recommend a separate fuse/breaker for the step-down transformer because it is a load in itself, and could potentially fail in a shorted state, should be sized for the max circuit load + 20%, and appropriate cable gauge to supply it.


2) Should I upgrade to a 60w step down transformer, which allows for thicker wire?

-You could, I suppose you could sum up the loads on the fuse panel and decide if you need more watts, it might run a little cooler to have a larger converter, not driven so hard.


3) Does there need to be a fuse between the 12v output of the transformer and the fuse block (I would think not because there are fuses on each circuit that originates at the fuse block), but I'm not sure.

-You shouldn't need a fuse there unless it's a long cable run, where the cable could have opportunity to pinch somewhere and ground-out before the fuse block, but if it's a short and safe run then the fuse block is the next line of defense.


4) Can the main fuse be a breaker instead of an ANL fuse?

-I don't see a problem with using fuses or breakers, as long as they are sized right, and not cheap breakers that may not really trip at their 'rated' values. Fuses are cheaper, breakers offer switch function for easy quick disconnect and reconnect as well.
 
Questions:

1) Should the step down transformer be connected to the battery through it's own 40amp breaker or directly through the main 200amp fuse? The wire on the step down transformer seems small to me.

-Yeah, I would recommend a separate fuse/breaker for the step-down transformer because it is a load in itself, and could potentially fail in a shorted state, should be sized for the max circuit load + 20%, and appropriate cable gauge to supply it.


2) Should I upgrade to a 60w step down transformer, which allows for thicker wire?

-You could, I suppose you could sum up the loads on the fuse panel and decide if you need more watts, it might run a little cooler to have a larger converter, not driven so hard.


3) Does there need to be a fuse between the 12v output of the transformer and the fuse block (I would think not because there are fuses on each circuit that originates at the fuse block), but I'm not sure.

-You shouldn't need a fuse there unless it's a long cable run, where the cable could have opportunity to pinch somewhere and ground-out before the fuse block, but if it's a short and safe run then the fuse block is the next line of defense.


4) Can the main fuse be a breaker instead of an ANL fuse?

-I don't see a problem with using fuses or breakers, as long as they are sized right, and not cheap breakers that may not really trip at their 'rated' values. Fuses are cheaper, breakers offer switch function for easy quick disconnect and reconnect as well.
Thanks. This is essentially what I got from someone else. Thanks for confirming.
 
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