Blade fuse melted ,solar

Submitted: Tuesday, May 09, 2023 at 14:25
ThreadID: 145623 Views:1746 Replies:6 FollowUps:9
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Electrical problem, The 40amp conventional size blade fuse has melted b4 blowing . From the 200watt solar panel to a victron 75 , 15amp solar regulator, regulator is mounted approximately 1m away with of good size cable . The fuse is mounted between the regulator and the battery which is approximately half a metre away ..Also i have found that the cable running to Anderson plug from panel has corroded for about 150 mm , out in the weather & was wondering if this should be expected ? Any explanation of these two problems would be very appreciated cheers in advance.
Cheers Nick b

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Reply By: Peter_n_Margaret - Tuesday, May 09, 2023 at 14:37

Tuesday, May 09, 2023 at 14:37
Crappy fuse?
No way will the 200W panel develop enough amps to blow a 40A fuse (at a nominal 12V) and in any case, the Victron will not deliver more than 15A.
The other (unlikely) possibility is that there is a short to earth at the Victron or somewhere along the cable after the fuse and before the Victron and the battery leak is blowing the fuse.
Cheers,
Peter
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Follow Up By: Member - nickb aka"boab" - Tuesday, May 09, 2023 at 18:10

Tuesday, May 09, 2023 at 18:10
Very unlikely that there is a short between the victron regulator and the battery.
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Reply By: Member - Duncan2H - Tuesday, May 09, 2023 at 14:45

Tuesday, May 09, 2023 at 14:45
I have seen this before.. not all fuse holders are equal, any voltage drop across the holder (resistance) due to poor contact between the blade fuse and the holder will cause substantial heat and the holder may melt around the fuse.

After completing any wiring, and from time to time its not a bad idea to check voltage drop between your battery and accessories etc. This test gives an overall indication of the total health of your circuit between power source and accessory - wire, fuse, crimps, joints etc.

Its really worth understanding how to measure voltage drop (if you dont' already, maybe you do).. good read here.. https://www.hagerty.com/media/maintenance-and-tech/measuring-voltage-drop/
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Follow Up By: Member - nickb aka"boab" - Tuesday, May 09, 2023 at 17:53

Tuesday, May 09, 2023 at 17:53
Cheers Duncan.. yeah as you can imagine I have no idea so I shall give that a read and thanks for your tip appreciate it
Cheers Nick b

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Reply By: Member - Cuppa - Tuesday, May 09, 2023 at 17:43

Tuesday, May 09, 2023 at 17:43
A fairly common problem with blade fuses, particularly when they are subject to moist & humid conditions & at higher currents. What happens is that an oxidating film builds up on the fuse blades creating resistance, As a result there is a heat build up which melts the fuse and or fuse holder.

https://rvbooks.com.au/blade-fuse-problems-in-caravans-they-may-burn-or-melt/
See 'My Profile' (below) for link to our Aussie travel blog, now in it's 6th year.

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Follow Up By: Member - nickb aka"boab" - Tuesday, May 09, 2023 at 18:08

Tuesday, May 09, 2023 at 18:08
So maybe I should be looking at a better fuse options and in a better location as this is in the open on top of the battery.. maybe I should be putting it with the regulator in the storage box ? . what is the best recommendation for a fuse/ circuit breaker .
I should also mentioned that the battery on a separate Circuit is fed power via the cars battery / alternator (redarc isolator switch) separate fuses that have never given any problem. Thanks for your reply
Cheers Nick b

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Reply By: Member - LeighW - Tuesday, May 09, 2023 at 20:37

Tuesday, May 09, 2023 at 20:37
If the fuse wasn't blown then it will be as above, dirty or weak contacts causing arcing etc.

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Reply By: qldcamper - Wednesday, May 10, 2023 at 07:24

Wednesday, May 10, 2023 at 07:24
All good advice above.
Cheap blade fuses have thinner legs and dont get enough pressure applied and develope local heat.
Suggest the ANL or MIDI type fuse and holder with screw in terminals.
Unless you have load attached at the reg end of the fuse 25 amp should be sufficient.
The corrosion you mentioned, is it green or white build up within the copper causing swelling of the insulation or just insulation perrishing because of sun exposure?
AnswerID: 643521

Follow Up By: Member - nickb aka"boab" - Wednesday, May 10, 2023 at 08:08

Wednesday, May 10, 2023 at 08:08
Corrosion, green / blackish with in the coper wire i would say it corroded off the wire at the terminal on the Anderson plug .
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Follow Up By: qldcamper - Wednesday, May 10, 2023 at 08:23

Wednesday, May 10, 2023 at 08:23
If the pins of the plug were soldered on (which I have no problem with) acid core solder or acid based flux may have been used which is a big no no on copper or just low quality copper thats been recycled a few times and containing a lot of impurities common in cheap chinese imported cable.
Whoever uses cheap 30 amp blade fuses is likley to use the cheapest cable they can find too.
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Follow Up By: qldcamper - Wednesday, May 10, 2023 at 08:26

Wednesday, May 10, 2023 at 08:26
As a matter of interest, where was the install done, did it come with the van, or whatever it is in, or installed later and how old is it?
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Follow Up By: Member - nickb aka"boab" - Wednesday, May 10, 2023 at 11:43

Wednesday, May 10, 2023 at 11:43
The cable are what came with the ritch panel & yes solded joint
The Panel i mounted on the roof of my tray ute . Cheers
Cheers Nick b

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Reply By: Member - DOZER - Thursday, May 11, 2023 at 17:53

Thursday, May 11, 2023 at 17:53
may not be the issue, but your solar reg is under size, 200 watts devided by 12 is not 15.
AnswerID: 643542

Follow Up By: Member - nickb aka"boab" - Thursday, May 11, 2023 at 19:02

Thursday, May 11, 2023 at 19:02
Hmm bugga 16.6 . What is the 12 ? Whem calculate the regulator size .
Panel sit flat so might never get full 200w ?
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Follow Up By: qldcamper - Friday, May 12, 2023 at 07:54

Friday, May 12, 2023 at 07:54
75/15 is perfectly suited to a 200 watt panel.
Re run the figures at 13.5 volts which is the minimum charging voltage that will push 200 watts through a 12 volt battery.

It doesnt really matter if it does on the rare occasion peak over 15 amps, it will just limit it to 15, Victron is very good quality gear, the engineers would have covered such a simple event.

Either way 200 watts is 50% of the capacity of a 40 amp fuse so it should have been able to carry that 24/7, not just for an hour or two each day.
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