Fuse or similar for solar controller

[tree monkey]

I have a 

Tristar mppt 45

It had an inline fuse of some sort in the positive line to the battery.

When I say had...

 

Anyway it needs updating can someone advise what I should use for

 

Controller to battery

And should I fit one panel to controller.

 

Is it correct for them to be on the live feed?

 

Thank you in advance 

[rusty69]

When you say had, what do you mean? Is the fuse holder still there?If so, and the fuse is no longer serviceable, could you not just replace it, assuming the cables are of an acceptable gauge?

 

From the manual:

 

Quote

Solar and battery fuses or DC breakers are required in the system. These protection devices are external to the TriStar MPPT 150V controller, and must be a maximum of 45 amps for the TSMPPT-30. 70 amps for the TS-MPPT 45 and 90 amps for the TS-MPPT-60.

Manual here:-

 

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/150V-TS-MPPT-Operators-Manual.pdf

 

 

Yes, a fuse or circuit breaker is required between the controller and battery in the positive cable. You could put a suitable switch between the panel and the controller too if you wanted.

Edited September 3, 2019 by rusty69

[Tony Brooks]

No real need for a fuse between panels and battery because the cable should be sized for volt drop and as such even if dead shorted would still not catch fire because the panels could not deliver sufficient current. Also the solar panel negative is probably totally isolated from the boat's negative so even if a positive solar cable conductor touched metal a short is unlikely. However I am not 100% sure of th controllers internal wiring and isolation.

[BEngo]

Tony, I think you are oversimplifying the wiring.

 

There must be a fuse between the battery and the controller to protect the cabling from a short  powered by the battery. For this reason the fuse should be as close as practicable to the battery.  Tracer suggest  15 cm as a max distance.

 

There does not need to be  fuse between panels and  controller , for the reasons you state.

N

[tree monkey]

20 minutes ago, rusty69 said:

When you say had, what do you mean? Is the fuse holder still there?If so, and the fuse is no longer serviceable, could you not just replace it, assuming the cables are of an acceptable gauge?

 

From the manual:

 

Manual here:-

 

https://2n1s7w3qw84d2ysnx3ia2bct-wpengine.netdna-ssl.com/wp-content/uploads/2014/02/150V-TS-MPPT-Operators-Manual.pdf

 

 

Yes, a fuse or circuit breaker is required between the controller and battery in the positive cable. You could put a suitable switch between the panel and the controller too if you wanted.

The fuse as fitted is no more, plus the holder is no longer with us, it's err buggerd and in such a state I carn't make out any useful info.

 

What I am asking is what is a suitable fuse tbh, carn't make head or tail of the manual 

10 minutes ago, Tony Brooks said:

No real need for a fuse between panels and battery because the cable should be sized for volt drop and as such even if dead shorted would still not catch fire because the panels could not deliver sufficient current. Also the solar panel negative is probably totally isolated from the boat's negative so even if a positive solar cable conductor touched metal a short is unlikely. However I am not 100% sure of th controllers internal wiring and isolation.

Thank you, electrics are something I struggle with for some reason, basic mechanical stuff I can cope but not electrics nope

Trees are easy

[Chewbacka]

10 minutes ago, tree monkey said:

The fuse as fitted is no more, plus the holder is no longer with us, it's err buggerd and in such a state I carn't make out any useful info.

 

What I am asking is what is a suitable fuse tbh, carn't make head or tail of the manual 

Thank you, electrics are something I struggle with for some reason, basic mechanical stuff I can cope but not electrics nope

Trees are easy

It case it helps, you probably want a midi fuse holder and fuse.

not suggesting you order from here, it’s just to show the sort of fuse holder you need.    https://www.ebay.co.uk/itm/MIDI-STRIP-LINK-FUSE-HOLDER-CAR-AUTO-HEAVY-DUTY-30-40-50-60-70-80-100-125-150AMP/191925440181?hash=item2cafa5ceb5:m:mB_JLM6mhYSpfzCXWSQFKKw

[Tony Brooks]

11 minutes ago, tree monkey said:

The fuse as fitted is no more, plus the holder is no longer with us, it's err buggerd and in such a state I carn't make out any useful info.

 

What I am asking is what is a suitable fuse tbh, carn't make head or tail of the manual 

 

Its the cable that will dictate the size of fuse but as long as the original cable was specified for voltdrop or larger than required you are all but safe to fit a fuse a few amps the next size up to maximum panel output. If you can identify the cables then we can give you a maximum fuse size but to do so is rather difficult.

[rusty69]

15 minutes ago, tree monkey said:

 

What I am asking is what is a suitable fuse tbh, carn't make head or tail of the manual 

It will depend on what size cable you have used.

[Chewbacka]

1 minute ago, Tony Brooks said:

Its the cable that will dictate the size of fuse but as long as the original cable was specified for voltdrop or larger than required you are all but safe to fit a fuse a few amps the next size up to maximum panel output. If you can identify the cables then we can give you a maximum fuse size but to do so is rather difficult.

If it’s a real MPPT controller with high voltage panels (series connected) the output current can be double the panel current.  So best to fuse on controller output.

[tree monkey]

It's a proper MPPT 

350 volts wired parallel 

6mm cable

 

I know the cable size thing gets complicated but it's stuff that's supposed to be used for solar supplied by a reputable company

[rusty69]

4 minutes ago, tree monkey said:

6mm cable

That sounds like the panel to controller cable. What is the controller to battery cable CSA and length?That will probably get you the answer you require.

[TheBiscuits]

10 minutes ago, tree monkey said:

350 volts wired parallel 

Bet you mean Watts.

[tree monkey]

2 minutes ago, rusty69 said:

That sounds like the panel to controller cable. What is the controller to battery cable CSA and length?That will probably get you the answer you require.

I don't know it appears to be about half the size and about 60cm long approx, I was considering replacing this with the thicker cable anyway, as I have spare and the live has an unnecessary join, plus I assumed thicker better

Just now, TheBiscuits said:

Bet you mean Watts.

Yeah see, me and electricity, it just doesn't work in my head, daft I know and I do try

[Chewbacka]

16 minutes ago, tree monkey said:

It's a proper MPPT 

350 volts wired parallel 

6mm cable

 

I know the cable size thing gets complicated but it's stuff that's supposed to be used for solar supplied by a reputable company

I think you mean 35v,  350v is much too high for a boat.

Added - I see above it’s 350w.

 

Your max controller current will be max panel watts divided by 12, though you will probably never actually achieve that.  To avoid nuisance fuse fails I would use a fuse rated at your max controller current plus 15%

 So at 350w that is a 35a fuse, but probably you won’t get one, so 40A 

 

 

 

Edited September 3, 2019 by Chewbacka

[tree monkey]

So in conclusion 45amps fuse yes?

As close to the battery as possible

5 minutes ago, Chewbacka said:

I think you mean 35v,  350v is much too high for a boat.

Your max controller current will be max panel watts divided by 12, though you will probably never actually achieve that.  To avoid nuisance fuse fails I would use a fuse rated at your max controller current plus 15%

Actually 350 watts my mistake kindly pointed out above

[Chewbacka]

1 minute ago, tree monkey said:

So in conclusion 45amps fuse yes?

As close to the battery as possible

Actually 350 watts my mistake kindly pointed out above

Big Fuses go up in tens so 40A is probably ok.

[tree monkey]

Ok so 40amp fuse, is that the consensus?

And thank you everyone. 

 

God I hate electrics 

[malp]

1 hour ago, BEngo said:

There must be a fuse between the battery and the controller to protect the cabling from a short  powered by the battery. For this reason the fuse should be as close as practicable to the battery.  Tracer suggest  15 cm as a max distance.

There is an argument that the fuse should not be close to the battery to minimise the risk of igniting any collected hydrogen gas if the fuse fails.

[WotEver]

42 minutes ago, malp said:

There is an argument that the fuse should not be close to the battery to minimise the risk of igniting any collected hydrogen gas if the fuse fails.

Not quite. The usual advice is that the fuse should be as close to the battery as possible but outside of the battery box. 

[David Mack]

Bimble's suggested arrangement.

[Tony Brooks]

11 hours ago, Chewbacka said:

If it’s a real MPPT controller with high voltage panels (series connected) the output current can be double the panel current.  So best to fuse on controller output.

That is the cable I was on about. No need to fuse the panel cables.

[Chewbacka]

10 hours ago, WotEver said:

Not quite. The usual advice is that the fuse should be as close to the battery as possible but outside of the battery box. 

Agreed.  As hydrogen is much lighter than air it will rise, so don’t put the fuse just above the battery box.  So long as the space around and above the the battery box is ‘open’ the fuse should be close to the battery box, if very close, then below the highest battery box vent is best.

[Tony Brooks]

Plus putting it in the box makes the chances of corrosion from acid mist greater.