Battery Isolators
Posted: Fri Jul 08, 2022 8:04 am
After reading about Derek's lock controller melting down, I started investigating battery cutout switches. I had a situation recently where a wire connecting a thermal breaker for the aux fan circuit disintegrated, broke and then contacted ground. It was alarming and a reminder of two things: 1) batteries have a LOT of energy; 2) when you buy cable from Amazon that's allegedly pure copper strand, it may not be, so for hi-amperage applications use wire from a reputable electrical supply source.
There are a flood of options for these, many are panel-mount for racing or RV applications. Despite the hassle of the E12's battery location and the need to open the hood to access a battery-mount option, I wanted an easy install. Most of the time the isolator would be used when doing work on the car. The top-post battery-mounted options come in two flavors, knife-blade and knob-style. I liked that with the knife-blade style you could visually confirm the connection status. You can also remove the knobs on most of the the knob-style rather than just loosening it, but then you have something loose to lose. I also figure in an emergency opening a knife-blade switch would be faster than loosening a hot knob from a short-circuited battery.
Unfortunately, most of the knife-blade products operate vertically and are rather tall for something sitting atop a battery.
Many of the products I found are cheaply made Chinese products using, at best (and if you can believe the description) brass plating over a zinc alloy. They're cheap and easy to install but we're talking about something that needs to work reliably, endure a fair number of duty cycles, and not break or corrode in an E12 engine bay.
I ended up going with a relatively expensive unit from McMaster-Carr at about $40 that is supposed to be made of brass. The knife-blade operates horizontally and the whole unit is low profile. I bought one for my 1990 F150 as well. I'll report back with impressions on whether they're worth the extra money.
Cheers,
Eric
There are a flood of options for these, many are panel-mount for racing or RV applications. Despite the hassle of the E12's battery location and the need to open the hood to access a battery-mount option, I wanted an easy install. Most of the time the isolator would be used when doing work on the car. The top-post battery-mounted options come in two flavors, knife-blade and knob-style. I liked that with the knife-blade style you could visually confirm the connection status. You can also remove the knobs on most of the the knob-style rather than just loosening it, but then you have something loose to lose. I also figure in an emergency opening a knife-blade switch would be faster than loosening a hot knob from a short-circuited battery.
Unfortunately, most of the knife-blade products operate vertically and are rather tall for something sitting atop a battery.
Many of the products I found are cheaply made Chinese products using, at best (and if you can believe the description) brass plating over a zinc alloy. They're cheap and easy to install but we're talking about something that needs to work reliably, endure a fair number of duty cycles, and not break or corrode in an E12 engine bay.
I ended up going with a relatively expensive unit from McMaster-Carr at about $40 that is supposed to be made of brass. The knife-blade operates horizontally and the whole unit is low profile. I bought one for my 1990 F150 as well. I'll report back with impressions on whether they're worth the extra money.
Cheers,
Eric