Morimoto HID Fuse Melted

So the fuse in the harness of my morimoto HID kit melted yesterday/today. Anyone know why this might happen?

• Have had the kit for 3+ years no issues.
• 50W ballasts.
• Did recently (2 months ago) install a second 300W amplifier so battery has been seeing more draw as of late. I don't think that matters but maybe?
• Battery is still stock at 3-4 years old.

It should be easy enough to clean up and replace the fuse but if there's an issue some where I'd like to identify and fix it.

Picture attached. Thoughts?

 

@TRSAndrew you ever seen this before?

 

One possible reason would be a loose connection.
Once a connection starts to get loose, it starts building heat. Heat makes the connection get looser. Chain reaction.

 

Did the fuse actually open?

 

I don't think so. They were still intermittently working when I checked the wiring and found the melted fuse. Here's a close up of whats left of the fuse after I pulled it out. Doesn't look like it ever blew to me...just got hot and melted everything around it.

 

Choosing Circuit Protection

"When matching circuit protection to the wire it protects, two facts contribute to the complexity of this task:

• Fuse Blow Point, Circuit Breaker Trip Value. The amperage at which fuses actually blow, and circuit breakers actually trip, is considerably higher than their nominal ratings. SEA, Maxi, ATO and AGC fuses, and most circuit breakers, blow or trip at about 130% of their rating. ANL fuses blow from 140% to as high as 266% of their rating. (See ANL Fuse Blow Point table below.)
• Current Heating. Wire and circuit protection devices heat up dramatically when they carry 100% of their rated value for several minutes or more. At about 150% of its current-carrying rating, wire generates enough heat to melt its insulation."

Fuse/Circuit Breaker Speed Explained

 

Heat at the fuse is usually poor contact on one or both fuse contacts. Usually between the fuse and its connectors. Can also be if you have high resistance on the load side.
Looking at the fuse holder, looks to be one of those cheap / bad quality items. So my guess would be the fuse holder itself. Personally, I’d cut it out and put in a quality fuse holder.

 

I don’t think wiring (or device) is the problem, so I wouldn’t have expected the fuse to blow. The fuse overheated due to resistance, see post above.

 

It is possible for the fuse to blow in this scenario. Increased resistance can add to current. But the Root Cause is identifiable by the melted fuse holder.

 

Hi resistance due to corrosion

 

Thanks for the insight. I intend to do as you suggested.

 

https://www.bluesea.com/support/art..._for_in_Your_Boats_Electrical_System_-_Part_1

"2. Running fuses continuously at full ratings

When matching circuit protection to the wire it protects, two facts contribute to the complexity of this task:

• The amperage at which fuses actually blow, and circuit breakers actually trip, is considerably higher than their nominal ratings, the rating usually marked on the unit.
• Wire and circuit protection devices heat up dramatically when they carry 100% of their rated value for several minutes or more.

SEA, Maxi, ATO and AGC fuses, and most circuit breakers, blow or trip at about 130% of their rating. ANL fuses blow from 140% to as high as 266% of their rating. When fuses carry 100% of their rated current value, they generate excessive heat. When wires carry 100% of their rated current value, they also generate excessive heat. In combination, the heat produced by fuses and wires carrying high current can melt wire insulation and fuse blocks. This heat generation may become critical when loads run for a considerable time. Large diameter wires take a long time to heat up, so short term operations like bow thrusters, windlasses, and macerator pumps seldom run long enough for this kind of heating to occur. For example, a 2/0 wire may take 25 minutes to approach its maximum temperature. In contrast, small diameter wires reach near peak temperature in less than 10 minutes.

For loads and appliances that run continuously for 10 to 30 minutes, choose circuit protection and wire so that current does not exceed 80% of their rating."

 

Possibly. Corrosion can set-in due to dissimilar metals. I like to use a compound called "Penatrox" on connections like this.

Make sure the new connections are clean and tight. Also, makes sure you strip back the damaged wiring as much as needed to find clean material to work with.

 

As long as the circuit components are "rated" for the load, this shouldn't be an issue. The circuit was only carrying 50W.

 

you said..

• Did recently (2 months ago) install a second 300W amplifier so battery has been seeing more draw as of late. I don't think that matters but maybe?
• Battery is still stock at 3-4 years old.

Keep in mind that every time your battery is under stress due to the new load (300 Watt amplifier) the voltage will drop.. When the voltage supplied from the battery drops, current (amps) go up..

 

300w amps are nothing i doubt that was the case.

Looks like the blade worked its way out and caused a heating issue.

 

Heat from a poor connection is most likely the problem. I would suggest replacing the fuse holder with a good quality one as well as using a
"Dielectric Silicone Compound"

$8 AGS Company Automotive Solutions Dielectric Silicone Grease, 1.25 oz, Seal and Protect Electrical Connections, Safe on Rubber and Plastic, Light Bulb Sockets, Spark Plug Boots and Battery Terminals

https://www.amazon.com/dp/B000IID41G/ref=cm_sw_em_r_mt_dp_U_r6eSDbTCPJ2H4 any brand will do.

Also try and use an ATC rather than an ATO type fuse. They are interchangeable but the ATO style has an opening for testing that is more prone to let moisture in and cause corrosion.

 

Sorry to see that! If you want to send this picture to us here at TRS we'll be glad to get it replaced for you even if it's outside of warranty:

support@theretrofitsource.com

 

Very good customer service..