inverter question

cheyenne

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hi guys . my mate is installing an inverter & want's to know if 50mm or two 25mm cables from battery to inverter should he use myself i have 50mm cable as he as seen on you -tube one clip with two 25mm cables which is the best guys thanks . cheyenne
 
Bigger is better but I suppose it all depends on the size of the inverter and how far away it is from the battery(ies)?

Regards,
Del
 
As above bigger is better, looking at the shocking price of cabling since I last bought some pre-pandemic you might be better off looking at Jump Leads as quite often they seem cheaper than equivalent cable, just be wary of the obviously cheap low quality Chinese Ones
 
The cable from battery to inverter should be protected by a fuse.
This means if you have TWO cables, you need to fuses.
This also means that if one fuse blows/fails, you will unknowingly be pulling all the current throught the one remaining intact circuit which could overload THAT cable until it's fuse blows.

the Ampacity of 2 X 25mm2 cables is the same as 1 X 50mm2 cable, but the real world application of using two is not as good.
 
wildebus said:
The cable from battery to inverter should be protected by a fuse.
This means if you have TWO cables, you need to fuses.
This also means that if one fuse blows/fails, you will unknowingly be pulling all the current throught the one remaining intact circuit which could overload THAT cable until it's fuse blows.

the Ampacity of 2 X 25mm2 cables is the same as 1 X 50mm2 cable, but the real world application of using two is not as good.
Click to expand...
Shouldn’t fuses be sized to protect the cables David? Don’t understand why it would overload, if one fuse blew surely they would both go as soon as you tried to draw more than the cable rating?
 
wildebus said:
the Ampacity of 2 X 25mm2 cables is the same as 1 X 50mm2 cable, but the real world application of using two is not as good.
Click to expand...
That's very true and also unless you are certain the cables are from the same batch then there may be some differences in cable manufacture which may cause greater resistance in one cable than the other which may in turn lead to further problems when using two cable
 
hi. thanks he said its going to be 50mm & he know about fuses etc etc thanks .cheyenne
 
nabsim said:
Shouldn’t fuses be sized to protect the cables David?
Click to expand...
indeed, the fuse should be lower than the cable rating. So instead of having say a 400A fuse on a 95mm2 cable, you might have a 200A fuse on each of the 50mm2 cables. (I am just plucking a number out the air here).

nabsim said:
Don’t understand why it would overload, if one fuse blew surely they would both go as soon as you tried to draw more than the cable rating?
Click to expand...
If only one fuse failed (not all fuses are created equally in terms of quality and the variance against the claimed rating can be dramatic - both higher AND lower) and maybe if there was a load close to the total rated load, you could have just one fuse fail as it is a poor fuse, or the other fuse still be intact as it is a poor fuse in the opposite direction.

Then the next time the inverter is used, all the current is going down just one of the two cables.
So two things occur now in fact ...
1) you are running all the load down that cable so even if you are not running the inverter to its rated capacity, you could be always close to the that single cables capacity. makes it run hot and heat = power loss = inefficiency
2) with all the load on the single cable, your voltage drop will be a lot greater than with both cables in play - again creating inefficiencies.
 
wildebus said:
indeed, the fuse should be lower than the cable rating. So instead of having say a 400A fuse on a 95mm2 cable, you might have a 200A fuse on each of the 50mm2 cables. (I am just plucking a number out the air here).


If only one fuse failed (not all fuses are created equally in terms of quality and the variance against the claimed rating can be dramatic - both higher AND lower) and maybe if there was a load close to the total rated load, you could have just one fuse fail as it is a poor fuse, or the other fuse still be intact as it is a poor fuse in the opposite direction.

Then the next time the inverter is used, all the current is going down just one of the two cables.
So two things occur now in fact ...
1) you are running all the load down that cable so even if you are not running the inverter to its rated capacity, you could be always close to the that single cables capacity. makes it run hot and heat = power loss = inefficiency
2) with all the load on the single cable, your voltage drop will be a lot greater than with both cables in play - again creating inefficiencies.
Click to expand...
But you could join the cables at both ends through one fuse, then it becomes a h duty cable, silly mind you unless space or bending around tight corners.
 
trevskoda said:
But you could join the cables at both ends through one fuse, then it becomes a h duty cable, silly mind you unless space or bending around tight corners.
Click to expand...
that is an option and I have often cut an extra opening on a megafuse cover to accommodate a second cable (y)
But better to use the single correct cable anyway unless there is a very specific reason not to. Bit silly not to as you say.
 
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