Fuse blowing but cannot see why?

[gus-lopez]

On the attached photos I am blowing the 20A fuse,marked B, when the ignition is switched on?
Originally it was wired direct to the starter battery & not through the normally closed switched relay. When it occurred the first time I thought that fitting that would remove any back feed? If the fuse B is uprated then fuse A blows ?
If the HL link on the Orion is removed then it does not happen?
Anyone any ideas?
Or do I just need a completely seperate solar supply to the starter battery?

I

 

[Richard n Ann]

What's the ignition switched relay for? It's like you've left the old charging system in and fitted a B to B as well

 

[gus-lopez]

What's the ignition switched relay for? It's like you've left the old charging system in and fitted a B to B as well

Initially there was no relay but the fuse,B, blew. I then thought it might be because it was getting a back feed from the starter battery so decided to install the ignition switched relay to protect the fuse. But your reply has just made me realise that it might be better ¡protected' if it was before the switched relay

I might have answered my own question here?

 

[Richard n Ann]

Initially there was no relay but the fuse,B, blew. I then thought it might be because it was getting a back feed from the starter battery so decided to install the ignition switched relay to protect the fuse. But your reply has just made me realise that it might be better ¡protected' if it was before the switched relay

I might have answered my own question here?

Just see if it works with fuse B removed. The relay cable is shorting out the input and output of the B2B

 

[Richard n Ann]

Fuse B must be blowing because of the large uncontrolled charging current into the lithium

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[Ditcha]

On the attached photos I am blowing the 20A fuse,marked B, when the ignition is switched on?
Originally it was wired direct to the starter battery & not through the normally closed switched relay. When it occurred the first time I thought that fitting that would remove any back feed? If the fuse B is uprated then fuse A blows ?
If the HL link on the Orion is removed then it does not happen?
Anyone any ideas?
Or do I just need a completely seperate solar supply to the starter battery?
View attachment 1046819View attachment 1046820

Would be better using diodes in each of the wires so the current can only flow in one direction from the mppt that might work just guessing really or just wire to the leisure battery and fit a battery master or the likes.

 

[Peavy]

On the attached photos I am blowing the 20A fuse,marked B, when the ignition is switched on?
Originally it was wired direct to the starter battery & not through the normally closed switched relay. When it occurred the first time I thought that fitting that would remove any back feed? If the fuse B is uprated then fuse A blows ?
If the HL link on the Orion is removed then it does not happen?
Anyone any ideas?
Or do I just need a completely seperate solar supply to the starter battery?
View attachment 1046819View attachment 1046820
I

Could be the input and output limited in the Orion is too high for that 20A fuse?

 

[Raul]

Could be the input and output limited in the Orion is too high for that 20A fuse?

That's my thought, input of the orion is 30A, so the 20A can't cope.

 

[Richard n Ann]

That's my thought, input of the orion is 30A, so the 20A can't cope.

Look at the diagram, the input output positives of the orion is shorted out with the relay wire

 

[gus-lopez]

Just see if it works with fuse B removed.

No it blew when there was just a fuse & no relay.

The relay cable is shorting out the input and output of the B2B

No I do not think so as above

Could be the input and output limited in the Orion is too high for that 20A fuse?

Yes that is what I was thinking as when I uprated the fuse in B it blew the other fuse A but I did not want to increase both fuse ratings whilst I was unsure what was causing it

That's my thought, input of the orion is 30A, so the 20A can't cope.

Yes good point. I have now moved fuse B to before the switched relay so it is now protected the instant the ignition is turned & before starting when the Orion would become active.
I have also put a switch in the HL link,like I am sure you have, so I can turn it off as it will really only be in use when travelling & there has been a large drain on the leisure battery.

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[Richard n Ann]

The orion unit input output positive is shorted out when the relay closes

 

[Raul]

Look at the diagram, the input output positives of the orion is shorted out with the relay wire

Yep, saw that now, when that relay is closed, the input and output positives of the orion are connected.
I'm squinting on my phone and broke my prescription readers, I'm using Lidl special till I get home; thats my excuse anyways.

 

[Raul]

I have also put a switch in the HL link,like I am sure you have, so I can turn it off

Yes good practice, at the moment I have no need for b2b the sun is more than enough. The switch comes handy and you decide when to call upon the b2b if needed.

 

[Richard n Ann]

Yes good practice, at the moment I have no need for b2b the sun is more than enough. The switch comes handy and you decide when to call upon the b2b if needed.

Me too, I can switch it off on the way home then so the lithium is stored at 60% or whatever

 

[Ditcha]

View attachment 1046880
The orion unit input output positive is shorted out when the relay closes

Adding one or two diodes from the mppt positives to each battery would stop that wouldn't it ?

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[Richard n Ann]

Adding one or two diodes from the mppt positives to each battery would stop that wouldn't it ?

Possibly if they were big stud diodes.. Also most Diodes have a 0.6v drop across them so it would throw the accuracy of the charging profile.
First job is remove fuse B and see if it works

 

[gus-lopez]

View attachment 1046880
The orion unit input output positive is shorted out when the relay closes

The problem is not when the normally closed relay is closed though. The Orion is not energised then?
Also The relay was never there originally so that might well have been the original problem?
When there was no relay as soon as you turned on the ignition & started it blew the fuse. Now when you turn on the ignition It is isolated when it opens. I can see though that even with that side isolated it can still short back threw the fuse B. So I think for now I will remove the solar output from the MPPT to the starter battery & come up with another idea.
Thanks for all the input