Loud noise from National Luna solenoid?

[Jacket]

For months I've been wondering what this odd "pop" noise is in my truck. It usually only happens once per trip, and often when the truck is still cold. My last working theory was a loose bolt in my cross-member that was hitting the frame.

Then over the weekend I was cleaning the dust out of my engine bay and I finally figured out what it is - the NL battery isolator. Upon startup, the system allows the primary battery to charge for 5 minutes, after which the isolator engages and allows the aux battery to charge. The loud "pop" is the solenoid engaging 5 minutes after startup.

So is this "normal?" Any other NL Isolater owners experience this? It is fairly loud - no trouble hearing or feeling it driving 35 mph down the road.

 

[Scott Brady]

So is this "normal?" Any other NL Isolater owners experience this? It is fairly loud - no trouble hearing or feeling it driving 35 mph down the road.

Where is it mounted? To the firewall? It is possible that the flat, metal panel is amplifying the sound. Maybe try a rubber bushing between the surfaces.

 

[Jacket]

It's close to the firewall, but on the driver side fender next to the brake master cylinder. Close enough to feel it in the pedals....

Here.

 

[Scott Brady]

I would try a rubber isolator between the screw head and the relay body, and between the relay body and the fender. That should attenuate most of the relay plunger noise.

 

[tibaal89]

So is this "normal?" Any other NL Isolater owners experience this? It is fairly loud - no trouble hearing or feeling it driving 35 mph down the road.

This is normal... my aux battery and NL stuff is mounted to the floor directly behind my drivers seat. It definitely has a big clunk to it - I think because it's a huge solenoid! :ylsmoke:

 

[cruiseroutfit]

Solenoids are mechanical and that mechanical switch will make a nice popping noise, audible enough to hear even over a revving motor at speed. Completely normal and per design.

If you suspect the noise source (not you but anyone else reading this), use your winch override feature and listen, you can make it click on and off at will and should allow you to replicate the noise your hearing.

 

[Jacket]

Sounds good - thanks all. Now that I know what it is, it won't bother me that much. It was more the fear of the unknown....

 

[p1michaud]

Sounds good - thanks all. Now that I know what it is, it won't bother me that much. It was more the fear of the unknown....

I've just installed a National Luna dual battery kit in the Landcruiser and have heard the same "pop" sound. In my Tacoma I had the Sure Power isolator set up and it was mounted on the firewall. It's a preferance thing but that "pop" sound on start up (Sure Power combines as soon as it sees 13.2V) was a reassuring feeling because I knew that the batteries were both receiving charge. Now with the NL kit, you have the fancy lights to tell you what's going on but I still listen for the "pop" to let me know everything is working as it should.