Green Knob Battery Switch Short

[SchnellSchweitz]

Just traced a short in my electrical system to the green knob battery switch.

I don't know if others have had issues with this product, but mine certainly has failed. The previous owner installed it and I believe it has always been faulty and I never realized it until now.

There have been a couple time where I lost power while driving and also have not been able to start it a few times. I thought it was something more serious...

You can see in the image below the base of the green knob was melting from shorts.



I replaced it with a similar looking black knob switch that totally disconnects. Seems to be a safer way to go.

Just thought I'd pass this along.

Eric J.

[tctnd]

Actually, the heat that was melting the knob would be the result of high resistance, not "shorts". Could be faulty manufacture or perhaps it wasn't tightened enough. I've used this style of disconnect without issues.
regards,
Phil

[hcoles]

you might be able to clean up both mating surfaces grease the threads and mating surfaces and remember to keep it tight and it should work fine

[rnln]

I have similar thing for a long time without any problem. Good thing about this product is that if you loose it, you are disconnecting it. One of the cause for melting is that it is not tightening it tight enought. You can try cleaning up the melted spot and may reuse it again.

[tobluforu]

I have the black knob version and if it's not connected just so, I can not start the car. I have to unscrew it and move it a tad and it fires. I'm about to go to a disconnect that has a key instead.

[sundevil64]

I've had the same problems with this device. I was driving and the car stopped running (64 vette). It wouldn't crank and there wasn't power to anything. I was pulling the car out of storage when it just stalled. The knob was tight, but still nothing. I took the disconnect out of the loop and the car started right up and ran fine.

[john walker's workshop]

those things have a very poor contact area. they're rough cast and not well finished where they contact, so you only get a couple of small points where they touch each other. i've had plenty of issues with them. a loose connection is a hot connection.

[wgirardot]

Originally Posted by SchnellSchweitz

Just traced a short in my electrical system to the green knob battery switch.

I don't know if others have had issues with this product, but mine certainly has failed. The previous owner installed it and I believe it has always been faulty and I never realized it until now.

There have been a couple time where I lost power while driving and also have not been able to start it a few times. I thought it was something more serious...

You can see in the image below the base of the green knob was melting from shorts.



I replaced it with a similar looking black knob switch that totally disconnects. Seems to be a safer way to go.

Just thought I'd pass this along.

Eric J.

If it is made in China, throw it out. Wont work/last

[911pcars]

Originally Posted by john walker's workshop

those things have a very poor contact area. they're rough cast and not well finished where they contact, so you only get a couple of small points where they touch each other. i've had plenty of issues with them. a loose connection is a hot connection.

One tell-tale sign the switch is on its last legs is when the knob is difficult to rotate. One one hand, it's an inexpensive but easily replaced part (HF for about $4) that could strand you, maybe in traffic. OTOH, it's a convenient method of disconnecting the battery for service or long term vehicle storage.

Mine was so bad, it affected cranking speed. I replaced with a new one and now it's good. I suggest lubing the threads and contact area with dielectric grease (DOW 111).

Sherwood

[dshepp806]

Great thread on this "piece". I caught JW's earlier posts on this particular "piece" and went ahead (against his advice) and had one installed, on a fresh (HEAVY!) battery,...assured that I would check this pup out frequently, gauging it's longevity, connectivity, etc.....still cringing at my actions contrare to an experienced, noted posters' (MECHANIC, to boot!) reccomendationsto this decision.

My Wrench installed a fresh battery back in Jan, this year, and I requested he install this very disconnect. I checked his work the day I brought her home and all worked as planned. It was only until last week that I happened to notice my voltage readings (driving) to dip to 12.8 VDC,..very "odd" for this car......she usually runs around 13.7 - 14.1 VDC. Agreed, I just got my AC working again and become accustomed the results of it's use, both temp and charge voltages while driving....STILL,..it seemed indicative of a possible "issue"....she's had a fresh alternator/VR within the last 2 years (found the ORIGINAL alt/reg in there,..from 1989) due to 2 (count 'em) due to voltage spikes registered on the radar detector.

Inanycase,...I cracked the bonnet last week and double-checked the connections and found that I was able to GAIN some tightness by turning the "green knob".....(ahem)....For seven (7) days now she's maintained a SOLID 13.7-13.8 volts, not caring too much of what's asked of her....

POINT IS,..should you have this "piece" installed, DO CHECK IT"S CONNECTIVITY (vibration can render it's intermittencies, as to connections.......) I plan to dissassemble this weekend and have a good look at contact areas,..see how she's faired over 6 months......reassemble.

I WILL say that when I grabbed the damned green knob (to tighten, 6 months later), finding (considerable) AMPLE tightening CW turn radius,..I certainly thought of JW..........


BEST!

Doyle




JW: should you have some good stories on this Piece"'s failure modes, would love to hear 'em. Hopefully, this assembly can survive with careful attention (to it)?

[dshepp806]

Never mind, JW.....Sorry,..post #7 sums it up....I missed it.


Are the other attachments baring of more contact area? Other than the "green one"?

BEST!

Doyle