Issues with rocker switches blowing (12v)

wannabecraig · 26-08-2023 2:46pm #1

I installed a rocker switch board and a fuse box (extended from the origional) onto the my boat about a 18 months ago and they were working well until a few weeks ago. I just went to turn them on one day, and all the switches that were connected to the new fuse board had blown (not lighting up or passing current). The other devices that were not connected to the new fuse board (connected to the orgional) but on a rocker switch didn't blow & devices that were connected to the new fuse board but not on the rocker switches are also fine.

So that is; Devices connected to rocker switch and new board don't work. Devices not connected to the new board but to rocker switch do work and devices connected to the new board but not to a rocker (VHF/Fish Finder/ Wiper) are working with issues.

The only thing I changed was I added a new motorized window wiper. This has an on/off switch, so doesn't need to be connected to the rocker switch. I had this on a 15apm fuse, until today, I switched down to 3apm. It's blowen the rockers twice now, so it's something that is going to happen again unless I fine the issue.

Is there any way the wiper could be blowing these rocker switches without blowing it's own fuse?

New fuse board - This is extended from the old one as you'll see in the pics below.

This is the origional fuse board, which I've extended to the new one.

Switched board

This is the new wiper. I had a 15apm fuse on this, but changed it to a 3apm today.

All input appreciated.

Lenar3556 · 26-08-2023 8:44pm

I have no experience of boats, but thoughts;

In the normal course of events ‘blown’ rocker switches would suggest that they were overloaded. I.e carrying a greater current than designed. They then overheated and failed. This is something that needs to be ruled out in the first instance, by confirming the current rating of the switch, and ensuring that the fuse is of an equal or lower rating.

The fact that these worked without issue for some time previously and the issue appears to only have arisen after installation of this new wiper motor is interesting.

There is such a think as ‘back emf’ whereby the wiper motor can effectively become a generator under certain conditions and feed higher voltages back into the supply network. This could potentially be the roof of your trouble.

I would say raise the issue with the wiper motor manufacturer in the first instance and see can they throw any light on it. There could be defect in it or need to install some form of protection to prevent significant back emf’s damaging your upstream installation.

Note I could be barking up the wrong tree with the above, but I think it would be worth considering. Was there any damage to any of the loads connected to these rockets?

10-10-20 · 26-08-2023 9:27pm

There are a few reported issues with that 12-way Kohree board, it seems to have some weak spots.

https://www.amazon.co.uk/product-reviews/B082KLBGGZ/ref%3Dacr_dp_hist_1?ie=UTF8&filterByStar=one_star&reviewerType=all_reviews#reviews-filter-bar

Did you confirm that 12v is reaching the switches using a multimeter? I'm wondering if it's just a bad connection, or maybe you have a back batch/design of switch?

Bruthal. · 26-08-2023 9:38pm

Yea if they all suddenly stopped together, it's likely a connection problem to the switch panel.

wannabecraig · 28-08-2023 11:24am

https://www.boards.ie/discussion/comment/121031457#Comment_121031457

Hi, thanks for this. I see the issues with this board is loose fuses and the board passing current even when not fused. This is not what I'm seeing. Generally the boat gets bashed about a LOT, so if it was loose, it's show up right away. But it's good to know that this is an possible problem with the board.

wannabecraig · 28-08-2023 11:28am

https://www.boards.ie/discussion/comment/121031223#Comment_121031223

Thanks for this. The rocker switches says it's rated for 20apm, there was a 15amp fuse on the motor, so it's very confusing. Also, the motor wasn’t going when the switched blew. I wasn't event using the boat. I'd just come down and go to turn them on and they'd be be blown. There is an alternator connected to the battery which pushing the voltage up to 15v, but again, this never blew the switches before.

Is it worth moving the wiper motor to a rocker switch instead of directly to the fuse board, or even moving

it to the other fuse board?

wannabecraig · 28-08-2023 11:29am

https://www.boards.ie/discussion/comment/121031540#Comment_121031540

Thanks. Where do you think the connection problem would be?

10-10-20 · 28-08-2023 11:34am

https://www.boards.ie/discussion/comment/121037353#Comment_121037353

I think you need to test it with a DMM to be honest.

Another thing is that you should put the DMM across the switch in resistance mode and measure the resistance across the contacts. It should obviously be 0 ohms when closed. That would validate whether all of the switches have failed as even if we take back-EMF into consideration - I can't see how they would all fail like that.

wannabecraig · 28-08-2023 3:46pm

Hi, yes, I did get a DMM on the connection to the switches, it definitely is receiving a current and the switch is definitely not passing current through. Also, when I just touch the spade connectors together (from the fuse board and device) then the device works, so it's definitely the switch. There were 5 switches that went at the same time, so I'm really confused.

These are the switches btw.

https://www.amazon.co.uk/gp/product/B088N73N7Y/ref=ox_sc_act_title_2?smid=AX9MVVUOG9GEQ&th=1

10-10-20 · 28-08-2023 3:53pm

Right, interesting.

Any chance you'd crack open a switch? I have a feeling that the contacts have either burnt away or jarred in melted plastic, but I guess the former.

wannabecraig · 28-08-2023 4:07pm

Yes, I'll open one tonight when I get home. They're broken so I've no issue opening them.

10-10-20 · 28-08-2023 4:09pm

https://www.boards.ie/discussion/comment/121038945#Comment_121038945

Snap some photos of the contact using the macro mode on your phone, if possible!

John.G · 28-08-2023 9:06pm

Wonder if there's a voltage drop across the switch(s) when carrying load, a 2V drop at 10A will generate 20 watts at the switch.

wannabecraig · 29-08-2023 11:19am

HI, Here are the close ups. There is some blue corosion, but I think these are new switches so not 100% sure why it's there.

Inside (this is the blub for the on light).

Behind the bulb

Inside the housing

Outside

10-10-20 · 29-08-2023 11:35am

https://www.boards.ie/discussion/comment/121041709#Comment_121041709

Yes, indications there of copper or a copper-alloy corrosion with that blue colour. These switches just aren't suited to a marine environment as I'd say they either got a splash or some salty water came off your hands.

Interesting also how one of the legs isn't tinned. Wonder what that's about?

wannabecraig · 29-08-2023 2:56pm

https://www.boards.ie/discussion/comment/121041776#Comment_121041776

That's the negitive for the light.

10-10-20 · 29-08-2023 3:00pm

https://www.boards.ie/discussion/comment/121042725#Comment_121042725

Anyway, now you know why they all failed. Salt corrosion.

wannabecraig · 29-08-2023 4:52pm

Do you really think that's the cause, I'm confused if that's the case for the following reasons.

All 5 switches blew at the same time, after two years working fine.
New ones installed blew after two weeks (other lasted two years).
Only ones on new fuseboard blew, others work fine, even though in the same environment.

Seems really odd if it's just salt.

Having said that, these are the newer ones I bought, and they don't seem water prrof.

https://www.amazon.co.uk/gp/product/B088N73N7Y/ref=ewc_pr_img_3?smid=AX9MVVUOG9GEQ&th=1

I'll get Marine level ones and see and see how I go. I'll know after a few weeks

https://www.amazon.co.uk/gp/product/B0BCYXRQSS/ref=ewc_pr_img_1?smid=A1DPAY3BCHO71J&psc=1

10-10-20 · 29-08-2023 5:05pm

https://www.boards.ie/discussion/comment/121043254#Comment_121043254

I can't explain it all, but the byproducts of salt corrosion are non-conductors, and that's why the switches physically do not pass electricity. Salt also has an interesting ability to collect on components and remain benign for a period if the humidity is low, with the salt becoming corrosive once the humidity goes above ~65%. So you may have had a combination of factors which lead to the salt only getting into the switches recently enough, maybe drying out, and then corroding the contacts once the humidity rose. Oh, and having voltage in the circuit will also affect the rate of corrosion, so maybe the battery was isolated for a period over the Winter, etc and has been connected for longer periods more recently, etc...

Open up more switches and see if it holds true.

wannabecraig · 29-08-2023 5:36pm

Yes, I'm going to go down tomorrow and open the rest of the them. I've ordered the ip65 ones now and I'll replace those as they are housed better.

wannabecraig · 02-10-2023 10:01am

I replaced with IP65 versions and all seems well, even after heavy rain. I think you were correct.

I also had changed the orentation of my boat, which meant that rain was more likely to get in, so I reckon that's what it was, thanks.

10-10-20 · 02-10-2023 1:21pm

https://www.boards.ie/discussion/comment/121183850#Comment_121183850

Good news, thanks for the update!

Issues with rocker switches blowing (12v)

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