Wirthco 20108 Knife-Blade T-4 Battery Disconnect Switch

I ordered this switch at 11pm, and got it two days later! Quick! Build quality is excellent and very robust.

This is a great way to connect two batteries without fear of draining your starting battery.

I am using it in my boat. Put the switch on one of the terminals on the second battery (this battery should also be connected to all peripheral electronics, like the radio, lights, cigarette lighter, etc). Turn it off when you are relaxing with the engine off, if the secondary battery is depleted, your main starting battery is unaffected. Flip the switch on when the engine is running and the alternator will charge the second battery! Also, if your primary battery is a dud, turn the switch on and start the boat with the secondary battery.

I purchased and wasted my Money on many other types of Battery Disconnect switches but none worked on my Dual Battery equipped 2012 Silverado 3500HD. General Motors did not provide any space around Battery terminals that would accept any other cut-off switch only their own supplied terminal assembly. I was able to modify the Wirthco 20108 Knife-Blade T-4 Battery Disconnect Switches to overcome this space problem. One I installed on the drivers side in a horizontal switch actuation plane, the other had to be modified at the contact blade to open the switch without using the full stroke. Worked out Great.

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I just returned from a 9 day vacation after using this disconnect to prevent my battery from discharging. Once re-engaged, the car started right up. No battery charging necessary.

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Have a slow drain in an older pickup and this was exactly what I needed to save the battery. 2 minutes to install.

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Installed this last week and I am very happy. These type of battery disconnects are becoming increasingly rare and for some reason are getting more and more expensive. I did a TON of research and this is the least expensive one I could find. It's a good product and does the job well.