Blue Seas Battery Switch Failure

[noelex 77]

Two Blue Seas 5510E battery switches have experienced failures, one shortly after the other. These were professionally installed seven years ago. The failures are identical, involving the failure of the plastic supports mounting the white plastic rear of the switch. This failure can lead to a short circuit (if wired as a double-pole switch).

In one case, an alarming amount of smoke and sparks were observed before the fuse blew, protecting the system.

The attached photographs illustrate the issue:

* The first photo shows the failed plastic supports circled in green. Notably, these posts have a stainless steel screw threaded through the center, leaving minimal plastic securing the two components.
* The second photo demonstrates two cams completing the circuit, with the arching on the bottom cam clearly visible.

It is hoped that this is a case of a production error resulting in a defective batch of switches. However, if you have any of these switches, please inspect the attachment of the front and rear components. If there is any play, replace the switch.

[Kelkara]

Originally Posted by noelex 77

This failure can lead to a short circuit (if wired as a double-pole switch).

Thanks for the warning about the failure mode of these switches.

I do have a question though. I understand that you have an aluminium boat, and hence a desire for double-pole switches ... but aren't these dual-circuit switches designed for two positive circuits, and so the failure in their intended use case shouldn't produce a dangerous positive to negative short. Do BlueSea endorse using it as a double-pole (positive + negative) switch?

[noelex 77]

Originally Posted by Kelkara

Thanks for the warning about the failure mode of these switches.

I do have a question though. I understand that you have an aluminium boat, and hence a desire for double-pole switches ... but aren't these dual-circuit switches designed for two positive circuits, and so the failure in their intended use case shouldn't produce a dangerous positive to negative short. Do BlueSea endorse using it as a double-pole (positive + negative) switch?

Yes, it is a common usage for this switch. From the instruction sheet:

"Switches positive and negative terminals of one battery bank , or two isolated battery banks"

[Kelkara]

Then it is a far more serious failure ... especially since these are often used in starting circuits, which on many boats are not fused.

[Matt Johnson]

Had the same failure too. Ours were installed in 2016, so maybe a similar batch. Hopefully corrected by now, but haven't investigated.

[FlyingScot]

Thank you for the heads up. I have two of these in use. One for each Multiplus to disconnect double 2/0 positive for each 12/3000. What was your use case, frequent usage, or rare, or something in between? What climate is the boat normally in? Is the area they are located on the vessel warm or cooler than ambient?

Thanks and sorry this happened to you.

[noelex 77]

Originally Posted by FlyingScot

Thank you for the heads up. I have two of these in use. One for each Multiplus to disconnect double 2/0 positive for each 12/3000. What was your use case, frequent usage, or rare, or something in between? What climate is the boat normally in? Is the area they are located on the vessel warm or cooler than ambient?

Thanks and sorry this happened to you.

Thanks.

The first switch to fail was the one that powers our main navigation instruments. It’s a relatively low power circuit (it has an 80A fuse) and it is only very rarely turned off. The switch is in a completely dry location. It has been subject to a wide range of ambient temperatures, from winter in Scotland to the tropics, but in short, the low current and infrequent operation should have been a breeze for this switch.

The second failure was also a rarely used switch. It’s an emergency bypass switch that lets us divert the house bank to start the engine. It’s only been used for testing, never in anger. It was protected with a 250A fuse.

[PippaB]

Thank you for posting, always interesting to see failure mode details.

It looks like the posts probably broke off right at the end of the screw that was in them, I'm guessing the transition from a fully filled hole to an unfilled one, which causes a step change in stiffness. I suppose that's why we use chamfers and fillets and angles. Would be interesting to see what would happen with slightly longer screws that just touch the base.

[CharlieJ]

OP: Suggest you contact BlueSea Tech Support. I know from personal experience that they want feedback on their products. Also, most of their products carry a lifetime warranty.

[TeddyDiver]

Might be better to use two separate single switches instead? Even if the switch wouldn't fail like this there's always a possibility to drop/hit the switch with something to break it and cause short circuit.. (note to myself)

[Tsuru]

We had the same failure too. The replacement was designed differently that leads me to believe it will be more robust. I replaced the second switch that had not failed and put a new one with our spares.

[noelex 77]

Originally Posted by PippaB

Thank you for posting, always interesting to see failure mode details.

It looks like the posts probably broke off right at the end of the screw that was in them, I'm guessing the transition from a fully filled hole to an unfilled one, which causes a step change in stiffness. I suppose that's why we use chamfers and fillets and angles. Would be interesting to see what would happen with slightly longer screws that just touch the base.

As you have rightly observed, there is a vulnerable area between the termination of the screw and the hollow plastic posts, but the fundamental problem seems to be that the only connections between the two halves of the switch are four posts of hollow, very thin plastic.

[leecea]

Off topic but Raymarine's wheel drive unit contains a similar plastic post and metal screw arrangement and the plastic posts often snap off like that. Cheap design.

[barnakiel]

I have seen an identical fail but I did not note the brand.


Seems undersized element or else wrong choice of the synthetic.


True said above send msg with images to the producer. They will be able to improve the design. Also make a recall of the iffy ones.


b.

[noelex 77]

Further research indicates a significant number of these switches have experienced failures in a remarkably similar manner. The majority of these failures appear to be associated with the slightly smaller M series switches. These switches are constructed in a similar manner, featuring thin plastic posts holding the two halves together. These posts appear to be identical to the "E” series switch.

For reference, I have included the following links:

https://www.thehulltruth.com/boating...h-failure.html

https://www.thehulltruth.com/boating...h-failure.html

https://www.thehulltruth.com/boating...h-failure.html

https://www.mbgforum.com/topic/3771-...witch-failure/

https://www.arimaowners.com/index.php?topic=23136.0

https://www.tidewaterowners.com/warn...ing-t2255.html

https://keywestboatsforum.com/blue-s...hes-t6740.html

https://www.tapatalk.com/groups/seah...sap-t3476.html

The positive news is that virtually all of these failures have been reported around approximately 2017, which coincides with when my switch was fitted. Subsequently, there appears to have been a redesign, with an updated version released. It is uncertain whether this redesign also applies to the “E” series switches, but there seem to be a limited number of reports of failures in recent years. I think it will be sensible to replace all nine of my switches.

A photograph of an “M” series switch exhibiting a near-identical breakage (not my own):